libtdevnc/x11vnc/x11vnc.1

.\" This file was automatically generated from x11vnc -help output.
.TH X11VNC "1" "April 2006" "x11vnc " "User Commands"
.SH NAME
x11vnc - allow VNC connections to real X11 displays
         version: 0.8.1, lastmod: 2006-04-16
.SH SYNOPSIS
.B x11vnc
[OPTION]...
.SH DESCRIPTION
.PP
Typical usage is:
.IP
Run this command in a shell on the remote machine "far-host"
with X session you wish to view:
.IP
x11vnc -display :0
.IP
Then run this in another window on the machine you are sitting at:
.IP
vncviewer far-host:0
.PP
Once x11vnc establishes connections with the X11 server and starts listening
as a VNC server it will print out a string: PORT=XXXX where XXXX is typically
5900 (the default VNC server port).  One would next run something like
this on the local machine: "vncviewer hostname:N" where "hostname" is
the name of the machine running x11vnc and N is XXXX - 5900, i.e. usually
"vncviewer hostname:0".
.PP
By default x11vnc will not allow the screen to be shared and it will exit
as soon as the client disconnects.  See \fB-shared\fR and \fB-forever\fR below to override
these protections.  See the FAQ for details how to tunnel the VNC connection
through an encrypted channel such as 
.IR ssh (1).
In brief:
.PP
% ssh -L 5900:localhost:5900 far-host 'x11vnc -localhost -display :0'
.PP
% vncviewer -encodings 'copyrect tight zrle hextile' localhost:0
.PP
Also, use of a VNC password (-rfbauth or \fB-passwdfile)\fR is strongly recommend.
.PP
For additional info see: http://www.karlrunge.com/x11vnc/
and  http://www.karlrunge.com/x11vnc/#faq
.PP
Rudimentary config file support: if the file $HOME/.x11vncrc exists then each
line in it is treated as a single command line option.  Disable with \fB-norc.\fR
For each option name, the leading character "-" is not required.  E.g. a
line that is either "forever" or "\fB-forever\fR" may be used and are equivalent.
Likewise "wait 100" or "\fB-wait\fR \fI100\fR" are acceptable and equivalent lines.
The "#" character comments out to the end of the line in the usual way
(backslash it for a literal).  Leading and trailing whitespace is trimmed off.
Lines may be continued with a "\\" as the last character of a line (it
becomes a space character).
.PP
.SH OPTIONS

.PP
\fB-display\fR \fIdisp\fR
.IP
X11 server display to connect to, usually :0.  The X
server process must be running on same machine and
support MIT-SHM.  Equivalent to setting the DISPLAY
environment variable to \fIdisp\fR.
.PP
\fB-auth\fR \fIfile\fR
.IP
Set the X authority file to be \fIfile\fR, equivalent to
setting the XAUTHORITY environment variable to \fIfile\fR
before startup.  Same as \fB-xauth\fR file.  See 
.IR Xsecurity (7)
,
.IR xauth (1)
man pages for more info.
.PP
\fB-id\fR \fIwindowid\fR
.IP
Show the window corresponding to \fIwindowid\fR not
the entire display.  New windows like popup menus,
transient toplevels, etc, may not be seen or may be
clipped.  Disabling SaveUnders or BackingStore in the
X server may help show them.  x11vnc may crash if the
window is initially partially obscured, changes size,
is iconified, etc.  Some steps are taken to avoid this
and the \fB-xrandr\fR mechanism is used to track resizes.  Use
.IR xwininfo (1)
to get the window id, or use "\fB-id\fR \fIpick\fR"
to have x11vnc run 
.IR xwininfo (1)
for you and extract
the id.  The \fB-id\fR option is useful for exporting very
simple applications (e.g. the current view on a webcam).
.PP
\fB-sid\fR \fIwindowid\fR
.IP
As \fB-id,\fR but instead of using the window directly it
shifts a root view to it: this shows SaveUnders menus,
etc, although they will be clipped if they extend beyond
the window.
.PP
\fB-clip\fR \fIWxH+X+Y\fR
.IP
Only show the sub-region of the full display that
corresponds to the rectangle with size WxH and offset
+X+Y.  The VNC display has size WxH (i.e. smaller than
the full display).  This also works for \fB-id/-sid\fR mode
where the offset is relative to the upper left corner
of the selected window.
.PP
\fB-flashcmap\fR
.IP
In 8bpp indexed color, let the installed colormap flash
as the pointer moves from window to window (slow).
Also try the \fB-8to24\fR option to avoid flash altogether.
.PP
\fB-shiftcmap\fR \fIn\fR
.IP
Rare problem, but some 8bpp displays use less than 256
colorcells (e.g. 16-color grayscale, perhaps the other
bits are used for double buffering) *and* also need to
shift the pixels values away from 0, .., ncells.  \fIn\fR
indicates the shift to be applied to the pixel values.
To see the pixel values set DEBUG_CMAP=1 to print out
a colormap histogram.  Example: \fB-shiftcmap\fR 240
.PP
\fB-notruecolor\fR
.IP
For 8bpp displays, force indexed color (i.e. a colormap)
even if it looks like 8bpp TrueColor (rare problem).
.PP
\fB-visual\fR \fIn\fR
.IP
Experimental option: probably does not do what you
think.  It simply *forces* the visual used for the
framebuffer; this may be a bad thing... (e.g. messes
up colors or cause a crash). It is useful for testing
and for some workarounds.  n may be a decimal number,
or 0x hex.  Run 
.IR xdpyinfo (1)
for the values.  One may
also use "TrueColor", etc. see <X11/X.h> for a list.
If the string ends in ":m" then for better or for
worse the visual depth is forced to be m.
.PP
\fB-overlay\fR
.IP
Handle multiple depth visuals on one screen, e.g. 8+24
and 24+8 overlay visuals (the 32 bits per pixel are
packed with 8 for PseudoColor and 24 for TrueColor).
.IP
Currently \fB-overlay\fR only works on Solaris via
.IR XReadScreen (3X11)
and IRIX using 
.IR XReadDisplay (3).
On Solaris there is a problem with image "bleeding"
around transient popup menus (but not for the menu
itself): a workaround is to disable SaveUnders
by passing the "\fB-su\fR" argument to Xsun (in
/etc/dt/config/Xservers).
.IP
Use \fB-overlay\fR as a workaround for situations like these:
Some legacy applications require the default visual to
be 8bpp (8+24), or they will use 8bpp PseudoColor even
when the default visual is depth 24 TrueColor (24+8).
In these cases colors in some windows will be incorrect
in x11vnc unless \fB-overlay\fR is used.  Another use of
\fB-overlay\fR is to enable showing the exact mouse cursor
shape (details below).
.IP
Under \fB-overlay,\fR performance will be somewhat slower
due to the extra image transformations required.
For optimal performance do not use \fB-overlay,\fR but rather
configure the X server so that the default visual is
depth 24 TrueColor and try to have all apps use that
visual (e.g. some apps have \fB-use24\fR or \fB-visual\fR options).
.PP
\fB-overlay_nocursor\fR
.IP
Sets \fB-overlay,\fR but does not try to draw the exact mouse
cursor shape using the overlay mechanism.
.PP
\fB-8to24\fR \fI[opts]\fR
.IP
Try this option if \fB-overlay\fR is not supported on your
OS, and you have a legacy 8bpp app that you want to
view on a multi-depth display with default depth 24
(and is 32 bpp) OR have a default depth 8 display with
depth 24 overlay windows for some apps.  This option
may not work on all X servers and hardware (tested
on XFree86/Xorg mga driver and Xsun).  The "opts"
string is not required and is described below.
.IP
This mode enables a hack where x11vnc monitors windows
within 3 levels from the root window.  If it finds
any that are 8bpp it extracts the indexed color
pixel values using XGetImage() and then applies a
transformation using the colormap(s) to create TrueColor
RGB values that it in turn inserts into bits 1-24 of
the framebuffer.  This creates a depth 24 "view"
of the display that is then exported via VNC.
.IP
Conversely, for default depth 8 displays, the depth
24 regions are read by XGetImage() and everything is
transformed and inserted into a depth 24 TrueColor
framebuffer.
.IP
Note that even if there are *no* depth 24 visuals or
windows (i.e. pure 8bpp), this mode is potentially
an improvement over \fB-flashcmap\fR because it avoids the
flashing and shows each window in the correct color.
.IP
This method appear to work, but may still have bugs
and it does hog resources.  If there are multiple 8bpp
windows using different colormaps, one may have to
iconify all but one for the colors to be correct.
.IP
There may be painting errors for clipping and switching
between windows of depths 8 and 24.  Heuristics are
applied to try to minimize the painting errors.  One can
also press 3 Alt_L's in a row to refresh the screen
if the error does not repair itself.  Also the option
\fB-fixscreen\fR 8=3.0 or \fB-fixscreen\fR V=3.0 may be used to
periodically refresh the screen at the cost of bandwidth
(every 3 sec for this example).
.IP
The [opts] string can contain the following settings.
Multiple settings are separated by commas.
.IP
For for some X servers with default depth 24 a
speedup may be achieved via the option "nogetimage".
This enables a scheme were XGetImage() is not used
to retrieve the 8bpp data.  Instead, it assumes that
the 8bpp data is in bits 25-32 of the 32bit X pixels.
There is no reason the X server should put the data
there for our poll requests, but some do and so the
extra steps to retrieve it can be skipped.  Tested with
mga driver with XFree86/Xorg.  For the default depth
8 case this option is ignored.
.IP
To adjust how often XGetImage() is used to poll the
non-default visual regions for changes, use the option
"poll=t" where "t" is a floating point time.
(default: 0.05)
.IP
Setting the option "level2" will limit the search
for non-default visual windows to two levels from the
root window.  Do this on slow machines where you know
the window manager only imposes one extra window between
the app window and the root window.
.IP
Also for very slow machines use "cachewin=t"
where t is a floating point amount of time to cache
XGetWindowAttributes results.  E.g. cachewin=5.0.
This may lead to the windows being unnoticed for this
amount of time when deiconifying, painting errors, etc.
.IP
While testing on a very old SS20 these options gave
tolerable response: \fB-8to24\fR poll=0.2,cachewin=5.0. For
this machine \fB-overlay\fR is supported and gives better
response.
.IP
Debugging for this mode can be enabled by setting
"dbg=1", "dbg=2", or "dbg=3".
.PP
\fB-scale\fR \fIfraction\fR
.IP
Scale the framebuffer by factor \fIfraction\fR.  Values
less than 1 shrink the fb, larger ones expand it.  Note:
image may not be sharp and response may be slower.
If \fIfraction\fR contains a decimal point "." it
is taken as a floating point number, alternatively
the notation "m/n" may be used to denote fractions
exactly, e.g. \fB-scale\fR 2/3
.IP
Scaling Options: can be added after \fIfraction\fR via
":", to supply multiple ":" options use commas.
If you just want a quick, rough scaling without
blending, append ":nb" to \fIfraction\fR (e.g. \fB-scale\fR
1/3:nb).  No blending is the default for 8bpp indexed
color, to force blending for this case use ":fb".
.IP
To disable \fB-scrollcopyrect\fR and \fB-wirecopyrect\fR under
\fB-scale\fR use ":nocr".  If you need to to enable them use
":cr" or specify them explicitly on the command line.
If a slow link is detected, ":nocr" may be applied
automatically.  Default: :cr
.IP
More esoteric options: for compatibility with vncviewers
the scaled width is adjusted to be a multiple of 4:
to disable this use ":n4".  ":in" use interpolation
scheme even when shrinking, ":pad" pad scaled width
and height to be multiples of scaling denominator
(e.g. 3 for 2/3).
.PP
\fB-scale_cursor\fR \fIfrac\fR
.IP
By default if \fB-scale\fR is supplied the cursor shape is
scaled by the same factor.  Depending on your usage,
you may want to scale the cursor independently of the
screen or not at all.  If you specify \fB-scale_cursor\fR
the cursor will be scaled by that factor.  When using
\fB-scale\fR mode to keep the cursor at its "natural" size
use "\fB-scale_cursor\fR \fI1\fR".  Most of the ":" scaling
options apply here as well.
.PP
\fB-viewonly\fR
.IP
All VNC clients can only watch (default off).
.PP
\fB-shared\fR
.IP
VNC display is shared, i.e. more than one viewer can
connect at the same time (default off).
.PP
\fB-once\fR
.IP
Exit after the first successfully connected viewer
disconnects, opposite of \fB-forever.\fR This is the Default.
.PP
\fB-forever\fR
.IP
Keep listening for more connections rather than exiting
as soon as the first client(s) disconnect. Same as \fB-many\fR
.PP
\fB-loop\fR
.IP
Create an outer loop restarting the x11vnc process
whenever it terminates.  \fB-bg\fR and \fB-inetd\fR are ignored in
this mode.  Useful for continuing even if the X server
terminates and restarts (you will need permission to
reconnect of course).   Use, e.g., \fB-loop100\fR to sleep
100 millisecs between restarts, etc.  Default is 2000ms
(i.e. 2 secs)  Use, e.g. \fB-loop300,5\fR to sleep 300 ms
and only loop 5 times.
.PP
\fB-timeout\fR \fIn\fR
.IP
Exit unless a client connects within the first n seconds
after startup.
.PP
\fB-inetd\fR
.IP
Launched by 
.IR inetd (1):
stdio instead of listening socket.
Note: if you are not redirecting stderr to a log file
(via shell 2> or \fB-o\fR option) you MUST also specify the \fB-q\fR
option, otherwise the stderr goes to the viewer which
will cause it to abort.  Specifying both \fB-inetd\fR and \fB-q\fR
and no \fB-o\fR will automatically close the stderr.
.PP
\fB-nofilexfer\fR
.IP
Disable the TightVNC file transfer extension.  (same as
\fB-disablefiletransfer).\fR  Note that when the \fB-viewonly\fR
option is supplied all file transfers are disabled.
Also clients that log in viewonly cannot transfer files.
However, if the remote control mechanism is used to
change the global or per-client viewonly state the
filetransfer permissions will NOT change.
.PP
\fB-http\fR
.IP
Instead of using \fB-httpdir\fR (see below) to specify
where the Java vncviewer applet is, have x11vnc try
to *guess* where the directory is by looking relative
to the program location and in standard locations
(/usr/local/share/x11vnc/classes, etc).
.PP
\fB-connect\fR \fIstring\fR
.IP
For use with "vncviewer -listen" reverse connections.
If \fIstring\fR has the form "host" or "host:port"
the connection is made once at startup.  Use commas
for a list of host's and host:port's.
.IP
Note that unlike most vnc servers, x11vnc will require a
password for reverse as well as for forward connections.
(provided password auth has been enabled, \fB-rfbauth,\fR etc)
If you do not want to require a password for reverse
connections set X11VNC_REVERSE_CONNECTION_NO_AUTH=1 in
your environment before starting x11vnc.
.IP
If \fIstring\fR contains "/" it is instead interpreted
as a file to periodically check for new hosts.
The first line is read and then the file is truncated.
Be careful for this usage mode if x11vnc is running as
root (e.g. via 
.IR gdm (1)
, etc).
.PP
\fB-vncconnect,\fR \fB-novncconnect\fR
.IP
Monitor the VNC_CONNECT X property set by the standard
VNC program 
.IR vncconnect (1).
When the property is
set to "host" or "host:port" establish a reverse
connection.  Using 
.IR xprop (1)
instead of vncconnect may
work (see the FAQ).  The \fB-remote\fR control mechanism uses
X11VNC_REMOTE channel, and this option disables/enables
it as well.  Default: \fB-vncconnect\fR
.PP
\fB-allow\fR \fIhost1[,host2..]\fR
.IP
Only allow client connections from hosts matching
the comma separated list of hostnames or IP addresses.
Can also be a numerical IP prefix, e.g. "192.168.100."
to match a simple subnet, for more control build
libvncserver with libwrap support (See the FAQ).  If the
list contains a "/" it instead is a interpreted as a
file containing addresses or prefixes that is re-read
each time a new client connects.  Lines can be commented
out with the "#" character in the usual way.
.PP
\fB-localhost\fR
.IP
Same as "\fB-allow\fR \fI127.0.0.1\fR".
.IP
Note: if you want to restrict which network interface
x11vnc listens on, see the \fB-listen\fR option below.
E.g. "\fB-listen\fR \fIlocalhost\fR" or "\fB-listen\fR \fI192.168.3.21\fR".
As a special case, the option "\fB-localhost\fR" implies
"\fB-listen\fR \fIlocalhost\fR".
.IP
For non-localhost \fB-listen\fR usage, if you use the remote
control mechanism (-R) to change the \fB-listen\fR interface
you may need to manually adjust the \fB-allow\fR list (and
vice versa) to avoid situations where no connections
(or too many) are allowed.
.PP
\fB-nolookup\fR
.IP
Do not use gethostbyname() or gethostbyaddr() to look up
host names or IP numbers.  Use this if name resolution
is incorrectly set up and leads to long pauses as name
lookups time out, etc.
.PP
\fB-input\fR \fIstring\fR
.IP
Fine tuning of allowed user input.  If \fIstring\fR does
not contain a comma "," the tuning applies only to
normal clients.  Otherwise the part before "," is for
normal clients and the part after for view-only clients.
"K" is for Keystroke input, "M" for Mouse-motion
input, "B" for Button-click input, and "C" is for
Clipboard input.  Their presence in the string enables
that type of input.  E.g. "\fB-input\fR \fIM\fR" means normal
users can only move the mouse and  "\fB-input\fR \fIKMBC,M\fR"
lets normal users do anything and enables view-only
users to move the mouse.  This option is ignored when
a global \fB-viewonly\fR is in effect (all input is discarded
in that case).
.PP
\fB-viewpasswd\fR \fIstring\fR
.IP
Supply a 2nd password for view-only logins.  The \fB-passwd\fR
(full-access) password must also be supplied.
.PP
\fB-passwdfile\fR \fIfilename\fR
.IP
Specify the libvncserver password via the first line
of the file \fIfilename\fR (instead of via \fB-passwd\fR on
the command line where others might see it via 
.IR ps (1)
).
See below for how to supply multiple passwords.
.IP
If the filename is prefixed with "rm:" it will be
removed after being read.  Perhaps this is useful in
limiting the readability of the file.  In general,
the password file should not be readable by untrusted
users (BTW: neither should the VNC \fB-rfbauth\fR file:
it is NOT encrypted).
.IP
If the filename is prefixed with "read:" it will
periodically be checked for changes and reread.
.IP
Note that only the first 8 characters of a password
are used.
.IP
If multiple non-blank lines exist in the file they are
all taken as valid passwords.  Blank lines are ignored.
Password lines may be "commented out" (ignored) if
they begin with the charactor "#" or the line contains
the string "__SKIP__".  Lines may be annotated by use
of the "__COMM__" string: from it to the end of the
line is ignored.  An empty password may be specified
via the "__EMPTY__" string on a line by itself (note
your viewer might not accept empty passwords).
.IP
If the string "__BEGIN_VIEWONLY__" appears on a
line by itself, the remaining passwords are used for
viewonly access.  For compatibility, as a special case
if the file contains only two password lines the 2nd
one is automatically taken as the viewonly password.
Otherwise the "__BEGIN_VIEWONLY__" token must be
used to have viewonly passwords.  (tip: make the 3rd
and last line be "__BEGIN_VIEWONLY__" to have 2
full-access passwords)
.PP
\fB-unixpw\fR \fI[list]\fR
.IP
Use Unix username and password authentication.  x11vnc
uses the 
.IR su (1)
program to verify the user's password.
[list] is an optional comma separated list of allowed
Unix usernames.  See below for per-user options that
can be applied.
.IP
A familiar "login:" and "Password:" dialog is
presented to the user on a black screen inside the
vncviewer.  The connection is dropped if the user fails
to supply the correct password in 3 tries or does not
send one before a 25 second timeout.  Existing clients
are view-only during this period.
.IP
Since the detailed behavior of 
.IR su (1)
can vary from
OS to OS and for local configurations, test the mode
carefully on your systems before using it in production.
Test different combinations of valid/invalid usernames
and valid/invalid passwords to see if it behaves as
expected.  x11vnc will attempt to be conservative and
reject a login if anything abnormal occurs.
.IP
On FreeBSD and the other BSD's by default it is
impossible for the user running x11vnc to validate
his *own* password via 
.IR su (1)
(evidently commenting out
the pam_self.so entry in /etc/pam.d/su eliminates this
problem).  So the x11vnc login will always *fail* for
this case (even when the correct password is supplied).
.IP
A possible workaround for this would be to start
x11vnc as root with the "\fB-users\fR \fI+nobody\fR" option to
immediately switch to user nobody.  Another source of
problems are PAM modules that prompt for extra info,
e.g. password aging modules.  These logins will fail
as well even when the correct password is supplied.
.IP
**IMPORTANT**: to prevent the Unix password being sent
in *clear text* over the network, one of two schemes
will be enforced: 1) the \fB-ssl\fR builtin SSL mode, or 2)
require both \fB-localhost\fR and \fB-stunnel\fR be enabled.
.IP
Method 1) ensures the traffic is encrypted between
viewer and server.  A PEM file will be required, see the
discussion under \fB-ssl\fR below (under some circumstances
a temporary one can be automatically generated).
.IP
Method 2) requires the viewer connection to appear
to come from the same machine x11vnc is running on
(e.g. from a ssh \fB-L\fR port redirection).  And that the
\fB-stunnel\fR SSL mode be used for encryption over the
network.(see the description of \fB-stunnel\fR below).
.IP
Note: as a convenience, if you 
.IR ssh (1)
in and start
x11vnc it will check if the environment variable
SSH_CONNECTION is set and appears reasonable.  If it
does, then the \fB-ssl\fR or \fB-stunnel\fR requirement will be
dropped since it is assumed you are using ssh for the
encrypted tunnelling.  \fB-localhost\fR is still enforced.
Use \fB-ssl\fR or \fB-stunnel\fR to force SSL usage even if
SSH_CONNECTION is set.
.IP
To override the above restrictions you can set
environment variables before starting x11vnc:
.IP
Set UNIXPW_DISABLE_SSL=1 to disable requiring either
\fB-ssl\fR or \fB-stunnel.\fR  Evidently you will be using a
different method to encrypt the data between the
vncviewer and x11vnc: perhaps 
.IR ssh (1)
or an IPSEC VPN.
.IP
Note that use of \fB-localhost\fR with 
.IR ssh (1)
is roughly
the same as requiring a Unix user login (since a Unix
password or the user's public key authentication is
used by sshd on the machine where x11vnc runs and only
local connections from that machine are accepted)
.IP
Set UNIXPW_DISABLE_LOCALHOST=1 to disable the \fB-localhost\fR
requirement in Method 2).  One should never do this
(i.e. allow the Unix passwords to be sniffed on the
network).
.IP
Regarding reverse connections (e.g. \fB-R\fR connect:host
and \fB-connect\fR host), when the \fB-localhost\fR constraint is
in effect then reverse connections can only be used
to connect to the same machine x11vnc is running on
(default port 5500).  Please use a ssh or stunnel port
redirection to the viewer machine to tunnel the reverse
connection over an encrypted channel. Note that in \fB-ssl\fR
mode reverse connection are disabled (see below).
.IP
In \fB-inetd\fR mode the Method 1) will be enforced (not
Method 2).  With \fB-ssl\fR in effect reverse connections
are disabled.  If you override this via env. var, be
sure to also use encryption from the viewer to inetd.
Tip: you can also have your own stunnel spawn x11vnc
in \fB-inetd\fR mode (thereby bypassing inetd).  See the FAQ
for details.
.IP
The user names in the comma separated [list] can have
per-user options after a ":", e.g. "fred:opts"
where "opts" is a "+" separated list of
"viewonly", "fullaccess", "input=XXXX", or
"deny", e.g. "karl,fred:viewonly,boss:input=M".
For "input=" it is the K,M,B,C described under \fB-input.\fR
.IP
If a user in the list is "*" that means those
options apply to all users.  It also means all users
are allowed to log in after supplying a valid password.
Use "deny" to explicitly deny some users if you use
"*" to set a global option.
.IP
There are also some utilities for testing password
if [list] starts with the "%" character.  See the
quick_pw() function in the source for details.
.PP
\fB-unixpw_nis\fR \fI[list]\fR
.IP
As \fB-unixpw\fR above, however do not use 
.IR su (1)
but rather
use the traditional 
.IR getpwnam (3)
+ 
.IR crypt (3)
method to
verify passwords instead.  This requires that the
encrypted passwords be readable.  Passwords stored
in /etc/shadow will be inaccessible unless x11vnc
is run as root.
.IP
This is called "NIS" mode simply because in most
NIS setups the user encrypted passwords are accessible
(e.g. "ypcat passwd").  NIS is not required for this
mode to work (only that 
.IR getpwnam (3)
return the encrypted
password is required), but it is unlikely it will work
for any other modern environment.  All of the \fB-unixpw\fR
options and contraints apply.
.PP
\fB-ssl\fR \fI[pem]\fR
.IP
Use the openssl library (www.openssl.org) to provide a
built-in encrypted SSL tunnel between VNC viewers and
x11vnc.  This requires libssl support to be compiled
into x11vnc at build time.  If x11vnc is not built
with libssl support it will exit immediately when \fB-ssl\fR
is prescribed.
.IP
[pem] is optional, use "\fB-ssl\fR \fI/path/to/mycert.pem\fR"
to specify a PEM certificate file to use to identify
and provide a key for this server.  See 
.IR openssl (1)
for
more info about PEMs and the \fB-sslGenCert\fR option below.
.IP
The connecting VNC viewer SSL tunnel can optionally
authenticate this server if they have the public
key part of the certificate (or a common certificate
authority, CA, is a more sophisicated way to verify
this server's cert, see \fB-sslGenCA\fR below).  This is
used to prevent man-in-the-middle attacks.  Otherwise,
if the VNC viewer accepts this server's key without
verification, at least the traffic is protected
from passive sniffing on the network (but NOT from
man-in-the-middle attacks).
.IP
If [pem] is not supplied and the 
.IR openssl (1)
utility
command exists in PATH, then a temporary, self-signed
certificate will be generated for this session (this
may take 5-30 seconds on slow machines).  If 
.IR openssl (1)
cannot be used to generate a temporary certificate
x11vnc exits immediately.
.IP
If successful in using 
.IR openssl (1)
to generate a
temporary certificate, the public part of it will be
displayed to stderr (e.g. one could copy it to the
client-side to provide authentication of the server to
VNC viewers.)  See following paragraphs for how to save
keys to reuse when x11vnc is restarted.
.IP
Set the env. var. X11VNC_SHOW_TMP_PEM=1 to have x11vnc
print out the entire certificate, including the PRIVATE
KEY part, to stderr.  One could reuse this cert if saved
in a [pem] file.  Similarly, set X11VNC_KEEP_TMP_PEM=1
to not delete the temporary PEM file: the file name
will be printed to stderr (so one could move it to
a safe place for reuse).  You will be prompted for a
passphrase for the private key.
.IP
If [pem] is "SAVE" then the certificate will be saved
to the file ~/.vnc/certs/server.pem, or if that file
exists it will be used directly.  Similarly, if [pem]
is "SAVE_PROMPT" the server.pem certificate will be
made based on your answers to its prompts for info such
as OrganizationalName, CommonName, etc.
.IP
Use "SAVE-<string>" and "SAVE_PROMPT-<string>"
to refer to the file ~/.vnc/certs/server-<string>.pem
instead.  E.g. "SAVE-charlie" will store to the file
~/.vnc/certs/server-charlie.pem
.IP
See \fB-ssldir\fR below to use a directory besides the
default ~/.vnc/certs
.IP
Example: x11vnc \fB-ssl\fR SAVE \fB-display\fR :0 ...
.IP
Reverse connections are disabled in \fB-ssl\fR mode because
there is no way to ensure that data channel will
be encrypted.  Set X11VNC_SSL_ALLOW_REVERSE=1 to
override this.
.IP
Your VNC viewer will also need to be able to connect
via SSL.  See the discussion below under \fB-stunnel\fR and
the FAQ (ssl_vncviewer script) for how this might be
achieved.  E.g. on Unix it is easy to write a shell
script that starts up stunnel and then vncviewer.
Also in the x11vnc source a SSL enabled Java VNC Viewer
applet is provided in the classes/ssl directory.
.PP
\fB-ssldir\fR \fI[dir]\fR
.IP
Use [dir] as an alternate ssl certificate and key
management toplevel directory.  The default is
~/.vnc/certs
.IP
This directory is used to store server and other
certificates and keys and also other materials.  E.g. in
the simplest case, "\fB-ssl\fR \fISAVE\fR" will store the x11vnc
server cert in [dir]/server.pem
.IP
Use of alternate directories via \fB-ssldir\fR allows you to
manage multiple VNC Certificate Authority (CA) keys.
Another use is if ~/.vnc/cert is on an NFS share you
might want your certificates and keys to be on a local
filesystem to prevent network snooping (for example
\fB-ssldir\fR /var/lib/x11vnc-certs).
.IP
\fB-ssldir\fR affects nearly all of the other \fB-ssl*\fR options,
e.g. \fB-ssl\fR SAVE, \fB-sslGenCert,\fR etc..
.PP
\fB-sslverify\fR \fI[path]\fR
.IP
For either of the \fB-ssl\fR or \fB-stunnel\fR modes, use [path]
to provide certificates to authenticate incoming VNC
*Client* connections (normally only the server is
authenticated in SSL.)  This can be used as a method
to replace standard password authentication of clients.
.IP
If [path] is a directory it contains the client (or CA)
certificates in separate files.  If [path] is a file,
it contains multiple certificates.  See special tokens
below.  These correspond to the "CApath = dir" and
"CAfile = file" stunnel options.  See the 
.IR stunnel (8)
manpage for details.
.IP
Examples:
x11vnc \fB-ssl\fR \fB-sslverify\fR ~/my.pem
x11vnc \fB-ssl\fR \fB-sslverify\fR ~/my_pem_dir/
.IP
Note that if [path] is a directory, it must contain
the certs in separate files named like <HASH>.0, where
the value of <HASH> is found by running the command
"openssl x509 \fB-hash\fR \fB-noout\fR \fB-in\fR file.crt". Evidently
one uses <HASH>.1 if there is a collision...
.IP
The the key-management utility "\fB-sslCertInfo\fR \fIHASHON\fR"
and "\fB-sslCertInfo\fR \fIHASHOFF\fR" will create/delete these
hashes for you automatically (via symlink) in the HASH
subdirs it manages.  Then you can point \fB-sslverify\fR to
the HASH subdir.
.IP
Special tokens: in \fB-ssl\fR mode, if [path] is not a file or
a directory, it is taken as a comma separated list of
tokens that are interpreted as follows:
.IP
If a token is "CA" that means load the CA/cacert.pem
file from the ssl directory.  If a token is "clients"
then all the files clients/*.crt in the ssl directory
are loaded.  Otherwise the file clients/token.crt
is attempted to be loaded.  As a kludge, use a token
like ../server-foo to load a server cert if you find
that necessary.
.IP
Use \fB-ssldir\fR to use a directory different from the
~/.vnc/certs default.
.IP
Note that if the "CA" cert is loaded you do not need
to load any of the certs that have been signed by it.
You will need to load any additional self-signed certs
however.
.IP
Examples:
x11vnc \fB-ssl\fR \fB-sslverify\fR CA
x11vnc \fB-ssl\fR \fB-sslverify\fR self:fred,self:jim
x11vnc \fB-ssl\fR \fB-sslverify\fR CA,clients
.IP
Usually "\fB-sslverify\fR \fICA\fR" is the most effective.
See the \fB-sslGenCA\fR and \fB-sslGenCert\fR options below for
how to set up and manage the CA framework.
.IP
NOTE: the following utilities, \fB-sslGenCA,\fR \fB-sslGenCert,\fR
\fB-sslEncKey,\fR and \fB-sslCertInfo\fR are provided for
completeness, but for casual usage they are overkill.
.IP
They provide VNC Certificate Authority (CA) key creation
and server / client key generation and signing.  So they
provide a basic Public Key management framework for
VNC-ing with x11vnc. (note that they require 
.IR openssl (1)
be installed on the system)
.IP
However, the simplest usage mode (where x11vnc
automatically generates its own, self-signed, temporary
key and the VNC viewers always accept it, e.g. accepting
via a dialog box) is probably safe enough for most
scenarios.  CA management is not needed.
.IP
To protect against Man-In-The-Middle attacks the
simplest mode can be improved by using "\fB-ssl\fR \fISAVE\fR"
to have x11vnc create a longer term self-signed
certificate, and then (safely) copy the corresponding
public key cert to the desired client machines (care
must be taken the private key part is not stolen;
you will be prompted for a passphrase).
.IP
So keep in mind no CA key creation or management
(-sslGenCA and \fB-sslGenCert)\fR is needed for either of
the above two common usage modes.
.IP
One might want to use \fB-sslGenCA\fR and \fB-sslGenCert\fR
if you had a large number of VNC client and server
workstations.  That way the administrator could generate
a single CA key with \fB-sslGenCA\fR and distribute its
certificate part to all of the workstations.
.IP
Next, he could create signed VNC server keys
(-sslGenCert server ...) for each workstation or user
that then x11vnc would use to authenticate itself to
any VNC client that has the CA cert.
.IP
Optionally, the admin could also make it so the
VNC clients themselves are authenticated to x11vnc
(-sslGenCert client ...)  For this \fB-sslverify\fR would be
pointed to the CA cert (and/or self-signed certs).
.IP
x11vnc will be able to use all of these cert and
key files.  On the VNC client side, they will need to
be "imported" somehow.  Web browsers have "Manage
Certificates" actions as does the Java applet plugin
Control Panel.  stunnel can also use these files (see
the ssl_vncviewer example script in the FAQ.)
.PP
\fB-sslGenCA\fR \fI[dir]\fR
.IP
Generate your own Certificate Authority private key,
certificate, and other files in directory [dir].
.IP
If [dir] is not supplied, a \fB-ssldir\fR setting is used,
or otherwise ~/.vnc/certs is used.
.IP
This command also creates directories where server and
client certs and keys will be stored.  The 
.IR openssl (1)
program must be installed on the system and available
in PATH.
.IP
After the CA files and directories are created the
command exits; the VNC server is not run.
.IP
You will be prompted for information to put into the CA
certificate.  The info does not have to be accurate just
as long as clients accept the cert for VNC connections.
You will also need to supply a passphrase of at least
4 characters for the CA private key.
.IP
Once you have generated the CA you can distribute
its certificate part, [dir]/CA/cacert.pem, to other
workstations where VNC viewers will be run.  One will
need to "import" this certicate in the applications,
e.g. Web browser, Java applet plugin, stunnel, etc.
Next, you can create and sign keys using the CA with
the \fB-sslGenCert\fR option below.
.IP
Examples:
x11vnc \fB-sslGenCA\fR
x11vnc \fB-sslGenCA\fR  ~/myCAdir
x11vnc \fB-ssldir\fR ~/myCAdir \fB-sslGenCA\fR
.IP
(the last two lines are equivalent)
.PP
\fB-sslGenCert\fR \fItype\fR \fIname\fR
.IP
Generate a VNC server or client certificate and private
key pair signed by the CA created previously with
\fB-sslGenCA.\fR  The 
.IR openssl (1)
program must be installed
on the system and available in PATH.
.IP
After the Certificate is generated the command exits;
the VNC server is not run.
.IP
The type of key to be generated is the string \fItype\fR.
It is either "server" (i.e. for use by x11vnc) or
"client" (for a VNC viewer).  Note that typically
only "server" is used: the VNC clients authenticate
themselves by a non-public-key method (e.g. VNC or
unix password).  \fItype\fR is required.
.IP
An arbitrary default name you want to associate with
the key is supplied by the \fIname\fR string.  You can
change it at the various prompts when creating the key.
\fIname\fR is optional.
.IP
If name is left blank for clients keys then "nobody"
is used.  If left blank for server keys, then the
primary server key: "server.pem" is created (this
is the saved one referenced by "\fB-ssl\fR \fISAVE\fR" when the
server is started)
.IP
If \fIname\fR begins with the string "self:" then
a self-signed certificate is created instead of one
signed by your CA key.
.IP
If \fIname\fR begins with the string "req:" then only a
key (.key) and a certificate signing *request* (.req)
are generated.  You can then send the .req file to
an external CA (even a professional one, e.g. Thawte)
and then combine the .key and the received cert into
the .pem file with the same basename.
.IP
The distinction between "server" and "client" is
simply the choice of output filenames and sub-directory.
This makes it so the \fB-ssl\fR SAVE-name option can easily
pick up the x11vnc PEM file this option generates.
And similarly makes it easy for the \fB-sslverify\fR option
to pick up your client certs.
.IP
There is nothing special about the filename or directory
location of either the "server" and "client" certs.
You can rename the files or move them to wherever
you like.
.IP
Precede this option with \fB-ssldir\fR [dir] to use a
directory other than the default ~/.vnc/certs You will
need to run \fB-sslGenCA\fR on that directory first before
doing any \fB-sslGenCert\fR key creation.
.IP
Note you cannot recreate a cert with exactly the same
distiguished name (DN) as an existing one.  To do so,
you will need to edit the [dir]/CA/index.txt file to
delete the line.
.IP
Similar to \fB-sslGenCA,\fR you will be prompted to fill
in some information that will be recorded in the
certificate when it is created.  Tip: if you know
the fully-quailified hostname other people will be
connecting to you can use that as the CommonName "CN"
to avoid some applications (e.g. web browsers and java
plugin) complaining it does not match the hostname.
.IP
You will also need to supply the CA private key
passphrase to unlock the private key created from
\fB-sslGenCA.\fR  This private key is used to sign the server
or client certicate.
.IP
The "server" certs can be used by x11vnc directly by
pointing to them via the \fB-ssl\fR [pem] option.  The default
file will be ~/.vnc/certs/server.pem.  This one would
be used by simply typing \fB-ssl\fR SAVE.  The pem file
contains both the certificate and the private key.
server.crt file contains the cert only.
.IP
The "client" cert + private key file will need
to be copied and imported into the VNC viewer
side applications (Web browser, Java plugin,
stunnel, etc.)  Once that is done you can delete the
"client" private key file on this machine since
it is only needed on the VNC viewer side.  The,
e.g. ~/.vnc/certs/clients/<name>.pem contains both
the cert and private key.  The <name>.crt contains the
certificate only.
.IP
NOTE: It is very important to know one should always
generate new keys with a passphrase.  Otherwise if an
untrusted user steals the key file he could use it to
masquerade as the x11vnc server (or VNC viewer client).
You will be prompted whether to encrypt the key with
a passphrase or not.  It is recommended that you do.
One inconvenience to a passphrase is that it must
be suppled every time x11vnc or the client app is
started up.
.IP
Examples:
.IP
x11vnc \fB-sslGenCert\fR server
x11vnc \fB-ssl\fR SAVE \fB-display\fR :0 ...
.IP
and then on viewer using ssl_vncviewer stunnel wrapper
(see the FAQ):
ssl_vncviewer \fB-verify\fR ./cacert.crt hostname:0
.IP
(this assumes the cacert.crt cert from \fB-sslGenCA\fR
was safely copied to the VNC viewer machine where
ssl_vncviewer is run)
.IP
Example using a name:
.IP
x11vnc \fB-sslGenCert\fR server charlie
x11vnc \fB-ssl\fR SAVE-charlie \fB-display\fR :0 ...
.IP
Example for a client certificate (rarely used):
.IP
x11vnc \fB-sslGenCert\fR client roger
scp ~/.vnc/certs/clients/roger.pem somehost:.
rm  ~/.vnc/certs/clients/roger.pem
.IP
x11vnc is then started with the the option \fB-sslverify\fR
~/.vnc/certs/clients/roger.crt (or simply \fB-sslverify\fR
roger), and on the viewer user on somehost could do
for example:
.IP
ssl_vncviewer \fB-mycert\fR ./roger.pem hostname:0
.PP
\fB-sslEncKey\fR \fI[pem]\fR
.IP
Utility to encrypt an existing PEM file with a
passphrase you supply when prompted.  For that key to be
used (e.g. by x11vnc) the passphrase must be supplied
each time.
.IP
The "SAVE" notation described under \fB-ssl\fR applies as
well. (precede this option with \fB-ssldir\fR [dir] to refer
a directory besides the default ~/.vnc/certs)
.IP
The 
.IR openssl (1)
program must be installed on the system
and available in PATH.  After the Key file is encrypted
the command exits; the VNC server is not run.
.IP
Examples:
x11vnc \fB-sslEncKey\fR /path/to/foo.pem
x11vnc \fB-sslEncKey\fR SAVE
x11vnc \fB-sslEncKey\fR SAVE-charlie
.PP
\fB-sslCertInfo\fR \fI[pem]\fR
.IP
Prints out information about an existing PEM file.
In addition the public certificate is also printed.
The 
.IR openssl (1)
program must be in PATH. Basically the
command "openssl x509 \fB-text"\fR is run on the pem.
.IP
The "SAVE" notation described under \fB-ssl\fR applies
as well.
.IP
Using  "LIST" will give a list of all certs being
managed (in the ~/.vnc/certs dir, use \fB-ssldir\fR to refer
to another dir).  "ALL" will print out the info for
every managed key (this can be very long).  Giving a
client or server cert shortname will also try a lookup
(e.g. \fB-sslCertInfo\fR charlie).  Use "LISTL" or "LL"
for a long (ls \fB-l\fR style) listing.
.IP
Using "HASHON" will create subdirs [dir]/HASH and
[dir]/HASH with OpenSSL hash filenames (e.g. 0d5fbbf1.0)
symlinks pointing up to the corresponding *.crt file.
([dir] is ~/.vnc/certs or one given by \fB-ssldir.)\fR
This is a useful way for other OpenSSL applications
(e.g. stunnel) to access all of the certs without
having to concatenate them.  x11vnc will not use them
unless you specifically reference them.  "HASHOFF"
removes these HASH subdirs.
.IP
The LIST, LISTL, LL, ALL, HASHON, HASHOFF words can
also be lowercase, e.g. "list".
.PP
\fB-sslDelCert\fR \fI[pem]\fR
.IP
Prompts you to delete all .crt .pem .key .req files
associated with [pem].  "SAVE" and lookups as in
\fB-sslCertInfo\fR apply as well.
.PP
\fB-stunnel\fR \fI[pem]\fR
.IP
Use the 
.IR stunnel (8)
(www.stunnel.org) to provide an
encrypted SSL tunnel between viewers and x11vnc.
.IP
This external tunnel method was implemented prior to the
integrated \fB-ssl\fR encryption described above.  It still
works well.  This requires stunnel to be installed
on the system and available via PATH (n.b. stunnel is
often installed in sbin directories).  Version 4.x of
stunnel is assumed (but see \fB-stunnel3\fR below.)
.IP
[pem] is optional, use "\fB-stunnel\fR \fI/path/to/stunnel.pem\fR"
to specify a PEM certificate file to pass to stunnel.
Whether one is needed or not depends on your stunnel
configuration.  stunnel often generates one at install
time.  See the stunnel documentation for details.
.IP
stunnel is started up as a child process of x11vnc and
any SSL connections stunnel receives are decrypted and
sent to x11vnc over a local socket.  The strings
"The SSL VNC desktop is ..." and "SSLPORT=..."
are printed out at startup to indicate this.
.IP
The \fB-localhost\fR option is enforced by default
to avoid people routing around the SSL channel.
Set STUNNEL_DISABLE_LOCALHOST=1 before starting x11vnc
to disable the requirement.
.IP
Your VNC viewer will also need to be able to connect via
SSL.  Unfortunately not too many do this.  UltraVNC has
an encryption plugin but it does not seem to be SSL.
.IP
Also, in the x11vnc distribution, a patched TightVNC
Java applet is provided in classes/ssl that does SSL
connections (only).
.IP
It is also not too difficult to set up an stunnel or
other SSL tunnel on the viewer side.  A simple example
on Unix using stunnel 3.x is:
.IP
% stunnel \fB-c\fR \fB-d\fR localhost:5901 \fB-r\fR remotehost:5900
% vncviewer localhost:1
.IP
For Windows, stunnel has been ported to it and there
are probably other such tools available.  See the FAQ
for more examples.
.PP
\fB-stunnel3\fR \fI[pem]\fR
.IP
Use version 3.x stunnel command line syntax instead of
version 4.x
.PP
\fB-https\fR \fI[port]\fR
.IP
Choose a separate HTTPS port (-ssl mode only).
.IP
In \fB-ssl\fR mode, it turns out you can use the
single VNC port (e.g. 5900) for both VNC and HTTPS
connections. (HTTPS is used to retrieve a SSL-aware
VncViewer.jar applet that is provided with x11vnc).
Since both use SSL the implementation was extended to
detect if HTTP traffic (i.e. GET) is taking place and
handle it accordingly.  The URL would be, e.g.:
.IP
https://mymachine.org:5900/
.IP
This is convenient for firewalls, etc, because only one
port needs to be allowed in.  However, this heuristic
adds a few seconds delay to each connection and can be
unreliable (especially if the user takes much time to
ponder the Certificate dialogs in his browser, Java VM,
or VNC Viewer applet.  That's right 3 separate "Are
you sure you want to connect" dialogs!)
.IP
So use the \fB-https\fR option to provide a separate, more
reliable HTTPS port that x11vnc will listen on.  If
[port] is not provided (or is 0), one is autoselected.
The URL to use is printed out at startup.
.IP
The SSL Java applet directory is specified via the
\fB-httpdir\fR option.  If not supplied it will try to guess
the directory as though the \fB-http\fR option was supplied.
.PP
\fB-usepw\fR
.IP
If no other password method was supplied on the command
line, first look for ~/.vnc/passwd and if found use it
with \fB-rfbauth;\fR next, look for ~/.vnc/passwdfile and
use it with \fB-passwdfile;\fR otherwise, prompt the user
for a password to create ~/.vnc/passwd and use it with
the \fB-rfbauth\fR option.  If none of these succeed x11vnc
exits immediately.
.IP
Note: \fB-unixpw\fR currently does not count as a password
method by this option.
.PP
\fB-storepasswd\fR \fIpass\fR \fIfile\fR
.IP
Store password \fIpass\fR as the VNC password in the
file \fIfile\fR.  Once the password is stored the
program exits.  Use the password via "\fB-rfbauth\fR \fIfile\fR"
.IP
If called with no arguments, "x11vnc \fB-storepasswd",\fR
the user is prompted for a password and it is stored
in the file ~/.vnc/passwd.  Called with one argument,
that will be the file to store the prompted password in.
.PP
\fB-nopw\fR
.IP
Disable the big warning message when you use x11vnc
without some sort of password.
.PP
\fB-accept\fR \fIstring\fR
.IP
Run a command (possibly to prompt the user at the
X11 display) to decide whether an incoming client
should be allowed to connect or not.  \fIstring\fR is
an external command run via 
.IR system (3)
or some special
cases described below.  Be sure to quote \fIstring\fR
if it contains spaces, shell characters, etc.  If the
external command returns 0 the client is accepted,
otherwise the client is rejected.  See below for an
extension to accept a client view-only.
.IP
If x11vnc is running as root (say from 
.IR inetd (1)
or from
display managers 
.IR xdm (1)
, 
.IR gdm (1)
, etc), think about the
security implications carefully before supplying this
option (likewise for the \fB-gone\fR option).
.IP
Environment: The RFB_CLIENT_IP environment variable will
be set to the incoming client IP number and the port
in RFB_CLIENT_PORT (or -1 if unavailable).  Similarly,
RFB_SERVER_IP and RFB_SERVER_PORT (the x11vnc side
of the connection), are set to allow identification
of the tcp virtual circuit.  The x11vnc process
id will be in RFB_X11VNC_PID, a client id number in
RFB_CLIENT_ID, and the number of other connected clients
in RFB_CLIENT_COUNT.  RFB_MODE will be "accept".
RFB_STATE will be PROTOCOL_VERSION, SECURITY_TYPE,
AUTHENTICATION, INITIALISATION, NORMAL, or UNKNOWN
indicating up to which state the client has acheived.
RFB_LOGIN_VIEWONLY will be 0, 1, or -1 (unknown).
RFB_USERNAME, RFB_LOGIN_TIME, and RFB_CURRENT_TIME may
also be set.
.IP
If \fIstring\fR is "popup" then a builtin popup window
is used.  The popup will time out after 120 seconds,
use "popup:N" to modify the timeout to N seconds
(use 0 for no timeout).
.IP
If \fIstring\fR is "xmessage" then an 
.IR xmessage (1)
invocation is used for the command.  xmessage must be
installed on the machine for this to work.
.IP
Both "popup" and "xmessage" will present an option
for accepting the client "View-Only" (the client
can only watch).  This option will not be presented if
\fB-viewonly\fR has been specified, in which case the entire
display is view only.
.IP
If the user supplied command is prefixed with something
like "yes:0,no:*,view:3 mycommand ..." then this
associates the numerical command return code with
the actions: accept, reject, and accept-view-only,
respectively.  Use "*" instead of a number to indicate
the default action (in case the command returns an
unexpected value).  E.g. "no:*" is a good choice.
.IP
Note that x11vnc blocks while the external command
or popup is running (other clients may see no updates
during this period).  So a person sitting a the physical
display is needed to respond to an popup prompt. (use
a 2nd x11vnc if you lock yourself out).
.IP
More \fB-accept\fR tricks: use "popupmouse" to only allow
mouse clicks in the builtin popup to be recognized.
Similarly use "popupkey" to only recognize
keystroke responses.  These are to help avoid the
user accidentally accepting a client by typing or
clicking. All 3 of the popup keywords can be followed
by +N+M to supply a position for the popup window.
The default is to center the popup window.
.PP
\fB-afteraccept\fR \fIstring\fR
.IP
As \fB-accept,\fR except to run a user supplied command after
a client has been accepted and authenticated. RFB_MODE
will be set to "afteraccept" and the other RFB_*
variables are as in \fB-accept.\fR  Unlike \fB-accept,\fR the
command return code is not interpreted by x11vnc.
Example: \fB-afteraccept\fR 'killall xlock &'
.PP
\fB-gone\fR \fIstring\fR
.IP
As \fB-accept,\fR except to run a user supplied command when
a client goes away (disconnects).  RFB_MODE will be
set to "gone" and the other RFB_* variables are as
in \fB-accept.\fR  The "popup" actions apply as well.
Unlike \fB-accept,\fR the command return code is not
interpreted by x11vnc.  Example: \fB-gone\fR 'xlock &'
.PP
\fB-users\fR \fIlist\fR
.IP
If x11vnc is started as root (say from 
.IR inetd (1)
or from
display managers 
.IR xdm (1)
, 
.IR gdm (1)
, etc), then as soon
as possible after connections to the X display are
established try to switch to one of the users in the
comma separated \fIlist\fR.  If x11vnc is not running as
root this option is ignored.
.IP
Why use this option?  In general it is not needed since
x11vnc is already connected to the X display and can
perform its primary functions.  The option was added
to make some of the *external* utility commands x11vnc
occasionally runs work properly.  In particular under
GNOME and KDE to implement the "\fB-solid\fR \fIcolor\fR" feature
external commands (gconftool-2 and dcop) must be run
as the user owning the desktop session.  Since this
option switches userid it also affects the userid used
to run the processes for the \fB-accept\fR and \fB-gone\fR options.
It also affects the ability to read files for options
such as \fB-connect,\fR \fB-allow,\fR and \fB-remap.\fR  Note that the
\fB-connect\fR file is also sometimes written to.
.IP
So be careful with this option since in many situations
its use can decrease security.
.IP
The switch to a user will only take place if the
display can still be successfully opened as that user
(this is primarily to try to guess the actual owner
of the session). Example: "\fB-users\fR \fIfred,wilma,betty\fR".
Note that a malicious user "barney" by quickly using
"xhost +" when logging in may get x11vnc to switch
to user "fred".  What happens next?
.IP
Under display managers it may be a long time before
the switch succeeds (i.e. a user logs in).  To make
it switch immediately regardless if the display
can be reopened prefix the username with the "+"
character. E.g. "\fB-users\fR \fI+bob\fR" or "\fB-users\fR \fI+nobody\fR".
The latter (i.e. switching immediately to user
"nobody") is probably the only use of this option
that increases security.
.IP
To immediately switch to a user *before* connections
to the X display are made or any files opened use the
"=" character: "\fB-users\fR \fI=bob\fR".  That user needs to
be able to open the X display of course.
.IP
The special user "guess=" means to examine the utmpx
database (see 
.IR who (1)
) looking for a user attached to
the display number (from DISPLAY or \fB-display\fR option)
and try him/her.  To limit the list of guesses, use:
"\fB-users\fR \fIguess=bob,betty\fR".
.IP
Even more sinister is the special user "lurk=" that
means to try to guess the DISPLAY from the utmpx login
database as well.  So it "lurks" waiting for anyone
to log into an X session and then connects to it.
Specify a list of users after the = to limit which
users will be tried.  To enable a different searching
mode, if the first user in the list is something like
":0" or ":0-2" that indicates a range of DISPLAY
numbers that will be tried (regardless of whether
they are in the utmpx database) for all users that
are logged in.  Examples: "\fB-users\fR \fIlurk=\fR" and also
"\fB-users\fR \fIlurk=:0-1,bob,mary\fR"
.IP
Be especially careful using the "guess=" and "lurk="
modes.  They are not recommended for use on machines
with untrustworthy local users.
.PP
\fB-noshm\fR
.IP
Do not use the MIT-SHM extension for the polling.
Remote displays can be polled this way: be careful this
can use large amounts of network bandwidth.  This is
also of use if the local machine has a limited number
of shm segments and \fB-onetile\fR is not sufficient.
.PP
\fB-flipbyteorder\fR
.IP
Sometimes needed if remotely polled host has different
endianness.  Ignored unless \fB-noshm\fR is set.
.PP
\fB-onetile\fR
.IP
Do not use the new copy_tiles() framebuffer mechanism,
just use 1 shm tile for polling.  Limits shm segments
used to 3.
.PP
\fB-solid\fR \fI[color]\fR
.IP
To improve performance, when VNC clients are connected
try to change the desktop background to a solid color.
The [color] is optional: the default color is "cyan4".
For a different one specify the X color (rgb.txt name,
e.g. "darkblue" or numerical "#RRGGBB").
.IP
Currently this option only works on GNOME, KDE, CDE,
and classic X (i.e. with the background image on the
root window).  The "gconftool-2" and "dcop" external
commands are run for GNOME and KDE respectively.
Other desktops won't work, e.g. Xfce (send us the
corresponding commands if you find them).  If x11vnc is
running as root (
.IR inetd (1)
or 
.IR gdm (1)
), the \fB-users\fR option
may be needed for GNOME and KDE.  If x11vnc guesses
your desktop incorrectly, you can force it by prefixing
color with "gnome:", "kde:", "cde:" or "root:".
.PP
\fB-blackout\fR \fIstring\fR
.IP
Black out rectangles on the screen. \fIstring\fR is a
comma separated list of WxH+X+Y type geometries for
each rectangle.  If one of the items on the list is the
string "noptr" the mouse pointer will not be allowed
to go into a blacked out region.
.PP
\fB-xinerama,\fR \fB-noxinerama\fR
.IP
If your screen is composed of multiple monitors
glued together via XINERAMA, and that screen is
not a rectangle this option will try to guess the
areas to black out (if your system has libXinerama).
default: \fB-xinerama\fR
.IP
In general, we have noticed on XINERAMA displays you
may need to use the "\fB-xwarppointer\fR" option if the mouse
pointer misbehaves.
.PP
\fB-xtrap\fR
.IP
Use the DEC-XTRAP extension for keystroke and mouse
input insertion.  For use on legacy systems, e.g. X11R5,
running an incomplete or missing XTEST extension.
By default DEC-XTRAP will be used if XTEST server grab
control is missing, use \fB-xtrap\fR to do the keystroke and
mouse insertion via DEC-XTRAP as well.
.PP
\fB-xrandr\fR \fI[mode]\fR
.IP
If the display supports the XRANDR (X Resize, Rotate
and Reflection) extension, and you expect XRANDR events
to occur to the display while x11vnc is running, this
options indicates x11vnc should try to respond to
them (as opposed to simply crashing by assuming the
old screen size).  See the 
.IR xrandr (1)
manpage and run
\'xrandr \fB-q'\fR for more info.  [mode] is optional and
described below.
.IP
Since watching for XRANDR events and trapping errors
increases polling overhead, only use this option if
XRANDR changes are expected.  For example on a rotatable
screen PDA or laptop, or using a XRANDR-aware Desktop
where you resize often.  It is best to be viewing with a
vncviewer that supports the NewFBSize encoding, since it
knows how to react to screen size changes.  Otherwise,
libvncserver tries to do so something reasonable for
viewers that cannot do this (portions of the screen
may be clipped, unused, etc).
.IP
"mode" defaults to "resize", which means create a
new, resized, framebuffer and hope all viewers can cope
with the change.  "newfbsize" means first disconnect
all viewers that do not support the NewFBSize VNC
encoding, and then resize the framebuffer.  "exit"
means disconnect all viewer clients, and then terminate
x11vnc.
.PP
\fB-padgeom\fR \fIWxH\fR
.IP
Whenever a new vncviewer connects, the framebuffer is
replaced with a fake, solid black one of geometry WxH.
Shortly afterwards the framebuffer is replaced with the
real one.  This is intended for use with vncviewers
that do not support NewFBSize and one wants to make
sure the initial viewer geometry will be big enough
to handle all subsequent resizes (e.g. under \fB-xrandr,\fR
\fB-remote\fR id:windowid, rescaling, etc.)
.PP
\fB-o\fR \fIlogfile\fR
.IP
Write stderr messages to file \fIlogfile\fR instead of
to the terminal.  Same as "\fB-logfile\fR \fIfile\fR".  To append
to the file use "\fB-oa\fR \fIfile\fR" or "\fB-logappend\fR \fIfile\fR".
.PP
\fB-flag\fR \fIfile\fR
.IP
Write the "PORT=NNNN" (e.g. PORT=5900) string to
\fIfile\fR in addition to stdout.  This option could be
useful by wrapper script to detect when x11vnc is ready.
.PP
\fB-rc\fR \fIfilename\fR
.IP
Use \fIfilename\fR instead of $HOME/.x11vncrc for rc file.
.PP
\fB-norc\fR
.IP
Do not process any .x11vncrc file for options.
.PP
\fB-h,\fR \fB-help\fR
.IP
Print this help text.
-?, \fB-opts\fR              Only list the x11vnc options.
.PP
\fB-V,\fR \fB-version\fR
.IP
Print program version and last modification date.
.PP
\fB-dbg\fR
.IP
Instead of exiting after cleaning up, run a simple
"debug crash shell" when fatal errors are trapped.
.PP
\fB-q\fR
.IP
Be quiet by printing less informational output to
stderr.  Same as \fB-quiet.\fR
.PP
\fB-bg\fR
.IP
Go into the background after screen setup.  Messages to
stderr are lost unless \fB-o\fR logfile is used.  Something
like this could be useful in a script:
.IP
port=`ssh $host "x11vnc -display :0 -bg" | grep PORT`
.IP
port=`echo "$port" | sed -e 's/PORT=//'`
.IP
port=`expr $port - 5900`
.IP
vncviewer $host:$port
.PP
\fB-modtweak,\fR \fB-nomodtweak\fR
.IP
Option \fB-modtweak\fR automatically tries to adjust the AltGr
and Shift modifiers for differing language keyboards
between client and host.  Otherwise, only a single key
press/release of a Keycode is simulated (i.e. ignoring
the state of the modifiers: this usually works for
identical keyboards).  Also useful in resolving cases
where a Keysym is bound to multiple keys (e.g. "<" + ">"
and "," + "<" keys).  Default: \fB-modtweak\fR
.PP
\fB-xkb,\fR \fB-noxkb\fR
.IP
When in modtweak mode, use the XKEYBOARD extension (if
the X display supports it) to do the modifier tweaking.
This is powerful and should be tried if there are still
keymapping problems when using \fB-modtweak\fR by itself.
The default is to check whether some common keysyms,
e.g. !, @, [, are only accessible via \fB-xkb\fR mode and if
so then automatically enable the mode.  To disable this
automatic detection use \fB-noxkb.\fR
.PP
\fB-skip_keycodes\fR \fIstring\fR
.IP
Ignore the comma separated list of decimal keycodes.
Perhaps these are keycodes not on your keyboard but
your X server thinks exist.  Currently only applies
to \fB-xkb\fR mode.  Use this option to help x11vnc in the
reverse problem it tries to solve: Keysym -> Keycode(s)
when ambiguities exist (more than one Keycode per
Keysym).  Run 'xmodmap \fB-pk'\fR to see your keymapping.
Example: "\fB-skip_keycodes\fR \fI94,114\fR"
.PP
\fB-sloppy_keys\fR
.IP
Experimental option that tries to correct some
"sloppy" key behavior.  E.g. if at the viewer you
press Shift+Key but then release the Shift before
Key that could give rise to extra unwanted characters
(usually only between keyboards of different languages).
Only use this option if you observe problems with
some keystrokes.
.PP
\fB-skip_dups,\fR \fB-noskip_dups\fR
.IP
Some VNC viewers send impossible repeated key events,
e.g. key-down, key-down, key-up, key-up all for the same
key, or 20 downs in a row for the same modifier key!
Setting \fB-skip_dups\fR means to skip these duplicates and
just process the first event. Note: some VNC viewers
assume they can send down's without the corresponding
up's and so you should not set this option for
these viewers (symptom: some keys do not autorepeat)
Default: \fB-noskip_dups\fR
.PP
\fB-add_keysyms,\fR \fB-noadd_keysyms\fR
.IP
If a Keysym is received from a VNC viewer and that
Keysym does not exist in the X server, then add the
Keysym to the X server's keyboard mapping on an unused
key.  Added Keysyms will be removed periodically and
also when x11vnc exits.  Default: \fB-add_keysyms\fR
.PP
\fB-clear_mods\fR
.IP
At startup and exit clear the modifier keys by sending
KeyRelease for each one. The Lock modifiers are skipped.
Used to clear the state if the display was accidentally
left with any pressed down.
.PP
\fB-clear_keys\fR
.IP
As \fB-clear_mods,\fR except try to release any pressed key.
Note that this option and \fB-clear_mods\fR can interfere
with a person typing at the physical keyboard.
.PP
\fB-remap\fR \fIstring\fR
.IP
Read Keysym remappings from file named \fIstring\fR.
Format is one pair of Keysyms per line (can be name
or hex value) separated by a space.  If no file named
\fIstring\fR exists, it is instead interpreted as this
form: key1-key2,key3-key4,...  See <X11/keysymdef.h>
header file for a list of Keysym names, or use 
.IR xev (1).
To map a key to a button click, use the fake Keysyms
"Button1", ..., etc. E.g: "\fB-remap\fR \fISuper_R-Button2\fR"
(useful for pasting on a laptop)
.IP
Dead keys: "dead" (or silent, mute) keys are keys that
do not produce a character but must be followed by a 2nd
keystroke.  This is often used for accenting characters,
e.g. to put "`" on top of "a" by pressing the dead
key and then "a".  Note that this interpretation
is not part of core X11, it is up to the toolkit or
application to decide how to react to the sequence.
The X11 names for these keysyms are "dead_grave",
"dead_acute", etc.  However some VNC viewers send the
keysyms "grave", "acute" instead thereby disabling
the accenting.  To work around this \fB-remap\fR can be used.
For example "\fB-remap\fR \fIgrave-dead_grave,acute-dead_acute\fR"
.IP
As a convenience, "\fB-remap\fR \fIDEAD\fR" applies these remaps:
.IP
      g     grave-dead_grave
      a     acute-dead_acute
      c     asciicircum-dead_circumflex
      t     asciitilde-dead_tilde
      m     macron-dead_macron
      b     breve-dead_breve
      D     abovedot-dead_abovedot
      d     diaeresis-dead_diaeresis
      o     degree-dead_abovering
      A     doubleacute-dead_doubleacute
      r     caron-dead_caron
      e     cedilla-dead_cedilla
.IP
.IP
If you just want a subset use the first letter
label, e.g. "\fB-remap\fR \fIDEAD=ga\fR" to get the first two.
Additional remaps may also be supplied via commas,
e.g.  "\fB-remap\fR \fIDEAD=ga,Super_R-Button2\fR".  Finally,
"DEAD=missing" means to apply all of the above as
long as the left hand member is not already in the
X11 keymap.
.PP
\fB-norepeat,\fR \fB-repeat\fR
.IP
Option \fB-norepeat\fR disables X server key auto repeat when
VNC clients are connected and VNC keyboard input is
not idle for more than 5 minutes.  This works around a
repeating keystrokes bug (triggered by long processing
delays between key down and key up client events: either
from large screen changes or high latency).
Default: \fB-norepeat\fR
.IP
Note: your VNC viewer side will likely do autorepeating,
so this is no loss unless someone is simultaneously at
the real X display.
.IP
Use "\fB-norepeat\fR \fIN\fR" to set how many times norepeat will
be reset if something else (e.g. X session manager)
undoes it.  The default is 2.  Use a negative value
for unlimited resets.
.PP
\fB-nofb\fR
.IP
Ignore video framebuffer: only process keyboard and
pointer.  Intended for use with Win2VNC and x2vnc
dual-monitor setups.
.PP
\fB-nobell\fR
.IP
Do not watch for XBell events. (no beeps will be heard)
Note: XBell monitoring requires the XKEYBOARD extension.
.PP
\fB-nosel\fR
.IP
Do not manage exchange of X selection/cutbuffer between
VNC viewers and the X server at all.
.PP
\fB-noprimary\fR
.IP
Do not poll the PRIMARY selection for changes to send
back to clients.  (PRIMARY is still set on received
changes, however).
.PP
\fB-nosetprimary\fR
.IP
Do not set the PRIMARY selection for changes received
from VNC clients.
.PP
\fB-noclipboard\fR
.IP
Do not poll the CLIPBOARD selection for changes to send
back to clients.  (CLIPBOARD is still set on received
changes, however).
.PP
\fB-nosetclipboard\fR
.IP
Do not set the CLIPBOARD selection for changes
received from VNC clients.
.PP
\fB-seldir\fR \fIstring\fR
.IP
If direction string is "send", only send the selection
to viewers, and if it is "recv" only receive it from
viewers.  To work around apps setting the selection
too frequently and messing up the other end.  You can
actually supply a comma separated list of directions,
including "debug" to turn on debugging output.
.PP
\fB-cursor\fR \fI[mode],\fR \fB-nocursor\fR
.IP
Sets how the pointer cursor shape (little icon at the
mouse pointer) should be handled.  The "mode" string
is optional and is described below.  The default
is to show some sort of cursor shape(s).  How this
is done depends on the VNC viewer and the X server.
Use \fB-nocursor\fR to disable cursor shapes completely.
.IP
Some VNC viewers support the TightVNC CursorPosUpdates
and CursorShapeUpdates extensions (cuts down on
network traffic by not having to send the cursor image
every time the pointer is moved), in which case these
extensions are used (see \fB-nocursorshape\fR and \fB-nocursorpos\fR
below to disable).  For other viewers the cursor shape
is written directly to the framebuffer every time the
pointer is moved or changed and gets sent along with
the other framebuffer updates.  In this case, there
will be some lag between the vnc viewer pointer and
the remote cursor position.
.IP
If the X display supports retrieving the cursor shape
information from the X server, then the default is
to use that mode.  On Solaris this can be done with
the SUN_OVL extension using \fB-overlay\fR (see also the
\fB-overlay_nocursor\fR option).  A similar overlay scheme
is used on IRIX.  Xorg (e.g. Linux) and recent Solaris
Xsun servers support the XFIXES extension to retrieve
the exact cursor shape from the X server.  If XFIXES
is present it is preferred over Overlay and is used by
default (see \fB-noxfixes\fR below).  This can be disabled
with \fB-nocursor,\fR and also some values of the "mode"
option below.
.IP
Note that under XFIXES cursors with transparency (alpha
channel) will usually not be exactly represented and one
may find Overlay preferable.  See also the \fB-alphacut\fR
and \fB-alphafrac\fR options below as fudge factors to try
to improve the situation for cursors with transparency
for a given theme.
.IP
The "mode" string can be used to fine-tune the
displaying of cursor shapes.  It can be used the
following ways:
.IP
"\fB-cursor\fR \fIarrow\fR" - just show the standard arrow
nothing more or nothing less.
.IP
"\fB-cursor\fR \fInone\fR" - same as "\fB-nocursor\fR"
.IP
"\fB-cursor\fR \fIX\fR" - when the cursor appears to be on the
root window, draw the familiar X shape.  Some desktops
such as GNOME cover up the root window completely,
and so this will not work, try "X1", etc, to try to
shift the tree depth.  On high latency links or slow
machines there will be a time lag between expected and
the actual cursor shape.
.IP
"\fB-cursor\fR \fIsome\fR" - like "X" but use additional
heuristics to try to guess if the window should have
a windowmanager-like resizer cursor or a text input
I-beam cursor.  This is a complete hack, but may be
useful in some situations because it provides a little
more feedback about the cursor shape.
.IP
"\fB-cursor\fR \fImost\fR" - try to show as many cursors as
possible.  Often this will only be the same as "some"
unless the display has overlay visuals or XFIXES
extensions available.  On Solaris and IRIX if XFIXES
is not available, \fB-overlay\fR mode will be attempted.
.PP
\fB-arrow\fR \fIn\fR
.IP
Choose an alternate "arrow" cursor from a set of
some common ones.  n can be 1 to 6.  Default is: 1
Ignored when in XFIXES cursor-grabbing mode.
.PP
\fB-noxfixes\fR
.IP
Do not use the XFIXES extension to draw the exact cursor
shape even if it is available.
.PP
\fB-alphacut\fR \fIn\fR
.IP
When using the XFIXES extension for the cursor shape,
cursors with transparency will not usually be displayed
exactly (but opaque ones will).  This option sets n as
a cutoff for cursors that have transparency ("alpha
channel" with values ranging from 0 to 255) Any cursor
pixel with alpha value less than n becomes completely
transparent.  Otherwise the pixel is completely opaque.
Default 240
.PP
\fB-alphafrac\fR \fIfraction\fR
.IP
With the threshold in \fB-alphacut\fR some cursors will become
almost completely transparent because their alpha values
are not high enough.  For those cursors adjust the
alpha threshold until fraction of the non-zero alpha
channel pixels become opaque.  Default 0.33
.PP
\fB-alpharemove\fR
.IP
By default, XFIXES cursors pixels with transparency have
the alpha factor multiplied into the RGB color values
(i.e. that corresponding to blending the cursor with a
black background).  Specify this option to remove the
alpha factor. (useful for light colored semi-transparent
cursors).
.PP
\fB-noalphablend\fR
.IP
In XFIXES mode do not send cursor alpha channel data
to libvncserver.  The default is to send it.  The
alphablend effect will only be visible in \fB-nocursorshape\fR
mode or for clients with cursorshapeupdates turned
off. (However there is a hack for 32bpp with depth 24,
it uses the extra 8 bits to store cursor transparency
for use with a hacked vncviewer that applies the
transparency locally.  See the FAQ for more info).
.PP
\fB-nocursorshape\fR
.IP
Do not use the TightVNC CursorShapeUpdates extension
even if clients support it.  See \fB-cursor\fR above.
.PP
\fB-cursorpos,\fR \fB-nocursorpos\fR
.IP
Option \fB-cursorpos\fR enables sending the X cursor position
back to all vnc clients that support the TightVNC
CursorPosUpdates extension.  Other clients will be able
to see the pointer motions. Default: \fB-cursorpos\fR
.PP
\fB-xwarppointer\fR
.IP
Move the pointer with 
.IR XWarpPointer (3X)
instead of
the XTEST extension.  Use this as a workaround
if the pointer motion behaves incorrectly, e.g.
on touchscreens or other non-standard setups.
Also sometimes needed on XINERAMA displays.
.PP
\fB-buttonmap\fR \fIstring\fR
.IP
String to remap mouse buttons.  Format: IJK-LMN, this
maps buttons I -> L, etc., e.g.  \fB-buttonmap\fR 13-31
.IP
Button presses can also be mapped to keystrokes: replace
a button digit on the right of the dash with :<sym>:
or :<sym1>+<sym2>: etc. for multiple keys. For example,
if the viewing machine has a mouse-wheel (buttons 4 5)
but the x11vnc side does not, these will do scrolls:
.IP
\fB-buttonmap\fR 12345-123:Prior::Next:
.IP
\fB-buttonmap\fR 12345-123:Up+Up+Up::Down+Down+Down:
.IP
See <X11/keysymdef.h> header file for a list of Keysyms,
or use the 
.IR xev (1)
program.  Note: mapping of button
clicks to Keysyms may not work if \fB-modtweak\fR or \fB-xkb\fR is
needed for the Keysym.
.IP
If you include a modifier like "Shift_L" the
modifier's up/down state is toggled, e.g. to send
"The" use :Shift_L+t+Shift_L+h+e: (the 1st one is
shift down and the 2nd one is shift up). (note: the
initial state of the modifier is ignored and not reset)
To include button events use "Button1", ... etc.
.PP
\fB-nodragging\fR
.IP
Do not update the display during mouse dragging events
(mouse button held down).  Greatly improves response on
slow setups, but you lose all visual feedback for drags,
text selection, and some menu traversals.  It overrides
any \fB-pointer_mode\fR setting.
.PP
\fB-wireframe\fR \fI[str],\fR \fB-nowireframe\fR
.IP
Try to detect window moves or resizes when a mouse
button is held down and show a wireframe instead of
the full opaque window.  This is based completely on
heuristics and may not always work: it depends on your
window manager and even how you move things around.
See \fB-pointer_mode\fR below for discussion of the "bogging
down" problem this tries to avoid.
Default: \fB-wireframe\fR
.IP
Shorter aliases:  \fB-wf\fR [str]  and \fB-nowf\fR
.IP
The value "str" is optional and, of course, is
packed with many tunable parameters for this scheme:
.IP
Format: shade,linewidth,percent,T+B+L+R,mod,t1+t2+t3+t4
Default: 0xff,3,0,32+8+8+8,all,0.15+0.30+5.0+0.125
.IP
If you leave nothing between commas: ",," the default
value is used.  If you don't specify enough commas,
the trailing parameters are set to their defaults.
.IP
"shade" indicate the "color" for the wireframe,
usually a greyscale: 0-255, however for 16 and 32bpp you
can specify an rgb.txt X color (e.g. "dodgerblue") or
a value > 255 is treated as RGB (e.g. red is 0xff0000).
"linewidth" sets the width of the wireframe in pixels.
"percent" indicates to not apply the wireframe scheme
to windows with area less than this percent of the
full screen.
.IP
"T+B+L+R" indicates four integers for how close in
pixels the pointer has to be from the Top, Bottom, Left,
or Right edges of the window to consider wireframing.
This is a speedup to quickly exclude a window from being
wireframed: set them all to zero to not try the speedup
(scrolling and selecting text will likely be slower).
.IP
"mod" specifies if a button down event in the
interior of the window with a modifier key (Alt, Shift,
etc.) down should indicate a wireframe opportunity.
It can be "0" or "none" to skip it, "1" or "all"
to apply it to any modifier, or "Shift", "Alt",
"Control", "Meta", "Super", or "Hyper" to only
apply for that type of modifier key.
.IP
"t1+t2+t3+t4" specify four floating point times in
seconds: t1 is how long to wait for the pointer to move,
t2 is how long to wait for the window to start moving
or being resized (for some window managers this can be
rather long), t3 is how long to keep a wireframe moving
before repainting the window. t4 is the minimum time
between sending wireframe "animations".  If a slow
link is detected, these values may be automatically
changed to something better for a slow link.
.PP
\fB-wirecopyrect\fR \fImode,\fR \fB-nowirecopyrect\fR
.IP
Since the \fB-wireframe\fR mechanism evidently tracks moving
windows accurately, a speedup can be obtained by
telling the VNC viewers to locally copy the translated
window region.  This is the VNC CopyRect encoding:
the framebuffer update doesn't need to send the actual
new image data.
.IP
Shorter aliases:  \fB-wcr\fR [mode]  and \fB-nowcr\fR
.IP
"mode" can be "never" (same as \fB-nowirecopyrect)\fR
to never try the copyrect, "top" means only do it if
the window was not covered by any other windows, and
"always" means to translate the orginally unobscured
region (this may look odd as the remaining pieces come
in, but helps on a slow link).  Default: "always"
.IP
Note: there can be painting errors or slow response
when using \fB-scale\fR so you may want to disable CopyRect
in this case "\fB-wirecopyrect\fR \fInever\fR" on the command
line or by remote-control.  Or you can also use the
"\fB-scale\fR \fIxxx:nocr\fR" scale option.
.PP
\fB-debug_wireframe\fR
.IP
Turn on debugging info printout for the wireframe
heuristics.  "\fB-dwf\fR" is an alias.  Specify multiple
times for more output.
.PP
\fB-scrollcopyrect\fR \fImode,\fR \fB-noscrollcopyrect\fR
.IP
Like \fB-wirecopyrect,\fR but use heuristics to try to guess
if a window has scrolled its contents (either vertically
or horizontally).  This requires the RECORD X extension
to "snoop" on X applications (currently for certain
XCopyArea and XConfigureWindow X protocol requests).
Examples: Hitting <Return> in a terminal window when the
cursor was at the bottom, the text scrolls up one line.
Hitting <Down> arrow in a web browser window, the web
page scrolls up a small amount.  Or scrolling with a
scrollbar or mouse wheel.
.IP
Shorter aliases:  \fB-scr\fR [mode]  and \fB-noscr\fR
.IP
This scheme will not always detect scrolls, but when
it does there is a nice speedup from using the VNC
CopyRect encoding (see \fB-wirecopyrect).\fR  The speedup
is both in reduced network traffic and reduced X
framebuffer polling/copying.  On the other hand, it may
induce undesired transients (e.g. a terminal cursor
being scrolled up when it should not be) or other
painting errors (window tearing, bunching-up, etc).
These are automatically repaired in a short period
of time.  If this is unacceptable disable the feature
with \fB-noscrollcopyrect.\fR
.IP
Screen clearing kludges:  for testing at least, there
are some "magic key sequences" (must be done in less
than 1 second) to aid repairing painting errors that
may be seen when using this mode:
.IP
3 Alt_L's   in a row: resend whole screen,
4 Alt_L's   in a row: reread and resend whole screen,
3 Super_L's in a row: mark whole screen for polling,
4 Super_L's in a row: reset RECORD context,
5 Super_L's in a row: try to push a black screen
.IP
note: Alt_L is the Left "Alt" key (a single key)
Super_L is the Left "Super" key (Windows flag).
Both of these are modifier keys, and so should not
generate characters when pressed by themselves.  Also,
your VNC viewer may have its own refresh hot-key
or button.
.IP
"mode" can be "never" (same as \fB-noscrollcopyrect)\fR
to never try the copyrect, "keys" means to try it
in response to keystrokes only, "mouse" means to
try it in response to mouse events only, "always"
means to do both. Default: "always"
.IP
Note: there can be painting errors or slow response
when using \fB-scale\fR so you may want to disable CopyRect
in this case "\fB-scrollcopyrect\fR \fInever\fR" on the command
line or by remote-control.  Or you can also use the
"\fB-scale\fR \fIxxx:nocr\fR" scale option.
.PP
\fB-scr_area\fR \fIn\fR
.IP
Set the minimum area in pixels for a rectangle
to be considered for the \fB-scrollcopyrect\fR detection
scheme.  This is to avoid wasting the effort on small
rectangles that would be quickly updated the normal way.
E.g. suppose an app updated the position of its skinny
scrollbar first and then shifted the large panel
it controlled.  We want to be sure to skip the small
scrollbar and get the large panel. Default: 60000
.PP
\fB-scr_skip\fR \fIlist\fR
.IP
Skip scroll detection for applications matching
the comma separated list of strings in \fIlist\fR.
Some applications implement their scrolling in
strange ways where the XCopyArea, etc, also applies
to invisible portions of the window: if we CopyRect
those areas it looks awful during the scroll and
there may be painting errors left after the scroll.
Soffice.bin is the worst known offender.
.IP
Use "##" to denote the start of the application class
(e.g. "##XTerm") and "++" to denote the start
of the application instance name (e.g. "++xterm").
The string your list is matched against is of the form
"^^WM_NAME##Class++Instance<same-for-any-subwindows>"
The "xlsclients \fB-la"\fR command will provide this info.
.IP
If a pattern is prefixed with "KEY:" it only applies
to Keystroke generated scrolls (e.g. Up arrow).  If it
is prefixed with "MOUSE:" it only applies to Mouse
induced scrolls (e.g. dragging on a scrollbar).
Default: ##Soffice.bin,##StarOffice
.PP
\fB-scr_inc\fR \fIlist\fR
.IP
Opposite of \fB-scr_skip:\fR this list is consulted first
and if there is a match the window will be monitored
via RECORD for scrolls irrespective of \fB-scr_skip.\fR
Use \fB-scr_skip\fR '*' to skip anything that does not match
your \fB-scr_inc.\fR  Use \fB-scr_inc\fR '*' to include everything.
.PP
\fB-scr_keys\fR \fIlist\fR
.IP
For keystroke scroll detection, only apply the RECORD
heuristics to the comma separated list of keysyms in
\fIlist\fR.  You may find the RECORD overhead for every
one of your keystrokes disrupts typing too much, but you
don't want to turn it off completely with "\fB-scr\fR \fImouse\fR"
and \fB-scr_parms\fR does not work or is too confusing.
.IP
The listed keysyms can be numeric or the keysym
names in the <X11/keysymdef.h> header file or from the
.IR xev (1)
program.  Example: "\fB-scr_keys\fR \fIUp,Down,Return\fR".
One probably wants to have application specific lists
(e.g. for terminals, etc) but that is too icky to think
about for now...
.IP
If \fIlist\fR begins with the "-" character the list
is taken as an exclude list: all keysyms except those
list will be considered.  The special string "builtin"
expands to an internal list of keysyms that are likely
to cause scrolls.  BTW, by default modifier keys,
Shift_L, Control_R, etc, are skipped since they almost
never induce scrolling by themselves.
.PP
\fB-scr_term\fR \fIlist\fR
.IP
Yet another cosmetic kludge.  Apply shell/terminal
heuristics to applications matching comma separated
list (same as for \fB-scr_skip/-scr_inc).\fR  For example an
annoying transient under scroll detection is if you
hit Enter in a terminal shell with full text window,
the solid text cursor block will be scrolled up.
So for a short time there are two (or more) block
cursors on the screen.  There are similar scenarios,
(e.g. an output line is duplicated).
.IP
These transients are induced by the approximation of
scroll detection (e.g. it detects the scroll, but not
the fact that the block cursor was cleared just before
the scroll).  In nearly all cases these transient errors
are repaired when the true X framebuffer is consulted
by the normal polling.  But they are distracting, so
what this option provides is extra "padding" near the
bottom of the terminal window: a few extra lines near
the bottom will not be scrolled, but rather updated
from the actual X framebuffer.  This usually reduces
the annoying artifacts.  Use "none" to disable.
Default: "term"
.PP
\fB-scr_keyrepeat\fR \fIlo-hi\fR
.IP
If a key is held down (or otherwise repeats rapidly) and
this induces a rapid sequence of scrolls (e.g. holding
down an Arrow key) the "scrollcopyrect" detection
and overhead may not be able to keep up.  A time per
single scroll estimate is performed and if that estimate
predicts a sustainable scrollrate of keys per second
between "lo" and "hi" then repeated keys will be
DISCARDED to maintain the scrollrate. For example your
key autorepeat may be 25 keys/sec, but for a large
window or slow link only 8 scrolls per second can be
sustained, then roughly 2 out of every 3 repeated keys
will be discarded during this period. Default: "4-20"
.PP
\fB-scr_parms\fR \fIstring\fR
.IP
Set various parameters for the scrollcopyrect mode.
The format is similar to that for \fB-wireframe\fR and packed
with lots of parameters:
.IP
Format: T+B+L+R,t1+t2+t3,s1+s2+s3+s4+s5
Default: 0+64+32+32,0.02+0.10+0.9,0.03+0.06+0.5+0.1+5.0
.IP
If you leave nothing between commas: ",," the default
value is used.  If you don't specify enough commas,
the trailing parameters are set to their defaults.
.IP
"T+B+L+R" indicates four integers for how close in
pixels the pointer has to be from the Top, Bottom, Left,
or Right edges of the window to consider scrollcopyrect.
If \fB-wireframe\fR overlaps it takes precedence.  This is a
speedup to quickly exclude a window from being watched
for scrollcopyrect: set them all to zero to not try
the speedup (things like selecting text will likely
be slower).
.IP
"t1+t2+t3" specify three floating point times in
seconds that apply to scrollcopyrect detection with
*Keystroke* input: t1 is how long to wait after a key
is pressed for the first scroll, t2 is how long to keep
looking after a Keystroke scroll for more scrolls.
t3 is how frequently to try to update surrounding
scrollbars outside of the scrolling area (0.0 to
disable)
.IP
"s1+s2+s3+s4+s5" specify five floating point times
in seconds that apply to scrollcopyrect detection with
*Mouse* input: s1 is how long to wait after a mouse
button is pressed for the first scroll, s2 is how long
to keep waiting for additional scrolls after the first
Mouse scroll was detected.  s3 is how frequently to
try to update surrounding scrollbars outside of the
scrolling area (0.0 to disable).  s4 is how long to
buffer pointer motion (to try to get fewer, bigger
mouse scrolls). s5 is the maximum time to spend just
updating the scroll window without updating the rest
of the screen.
.PP
\fB-fixscreen\fR \fIstring\fR
.IP
Periodically "repair" the screen based on settings
in \fIstring\fR.  Hopefully you won't need this option,
it is intended for cases when the \fB-scrollcopyrect\fR or
\fB-wirecopyrect\fR features leave too many painting errors,
but it can be used for any scenario.  This option
periodically performs costly operations and so
interactive response may be reduced when it is on.
You can use 3 Alt_L's (the Left "Alt" key) taps in
a row (as described under \fB-scrollcopyrect)\fR instead to
manually request a screen repaint when it is needed.
.IP
\fIstring\fR is a comma separated list of one or more of
the following: "V=t", "C=t", "X=t", and "8=t".
In these "t" stands for a time in seconds (it is
a floating point even though one should usually use
values > 2 to avoid wasting resources).  V sets how
frequently the entire screen should be sent to viewers
(it is like the 3 Alt_L's).  C sets how long to wait
after a CopyRect to repaint the full screen.  X sets
how frequently to reread the full X11 framebuffer from
the X server and push it out to connected viewers.
Use of X should be rare, please report a bug if you
find you need it. 8= applies only for \fB-8to24\fR mode: it
sets how often the non-default visual regions of the
screen (e.g. 8bpp windows) are refreshed.  Examples:
\fB-fixscreen\fR V=10 \fB-fixscreen\fR C=10
.PP
\fB-debug_scroll\fR
.IP
Turn on debugging info printout for the scroll
heuristics.  "\fB-ds\fR" is an alias.  Specify it multiple
times for more output.
.PP
\fB-noxrecord\fR
.IP
Disable any use of the RECORD extension.  This is
currently used by the \fB-scrollcopyrect\fR scheme and to
monitor X server grabs.
.PP
\fB-grab_buster,\fR \fB-nograb_buster\fR
.IP
Some of the use of the RECORD extension can leave a
tiny window for XGrabServer deadlock.  This is only if
the whole-server grabbing application expects mouse or
keyboard input before releasing the grab.  It is usually
a window manager that does this.  x11vnc takes care to
avoid the the problem, but if caught x11vnc will freeze.
Without \fB-grab_buster,\fR the only solution is to go the
physical display and give it some input to satisfy the
grabbing app.  Or manually kill and restart the window
manager if that is feasible.  With \fB-grab_buster,\fR x11vnc
will fork a helper thread and if x11vnc appears to be
stuck in a grab after a period of time (20-30 sec) then
it will inject some user input: button clicks, Escape,
mouse motion, etc to try to break the grab.  If you
experience a lot of grab deadlock, please report a bug.
.PP
\fB-debug_grabs\fR
.IP
Turn on debugging info printout with respect to
XGrabServer() deadlock for \fB-scrollcopyrect__mode_.\fR
.PP
\fB-debug_sel\fR
.IP
Turn on debugging info printout with respect to
PRIMARY, CLIPBOARD, and CUTBUFFER0 selections.
.PP
\fB-pointer_mode\fR \fIn\fR
.IP
Various pointer motion update schemes. "\fB-pm\fR" is
an alias.  The problem is pointer motion can cause
rapid changes on the screen: consider the rapid
changes when you drag a large window around opaquely.
Neither x11vnc's screen polling and vnc compression
routines nor the bandwidth to the vncviewers can keep
up these rapid screen changes: everything will bog down
when dragging or scrolling.  So a scheme has to be used
to "eat" much of that pointer input before re-polling
the screen and sending out framebuffer updates. The
mode number \fIn\fR can be 0 to 4 and selects one of
the schemes desribed below.
.IP
Note that the \fB-wireframe\fR and \fB-scrollcopyrect__mode_s\fR
complement \fB-pointer_mode\fR by detecting (and improving)
certain periods of "rapid screen change".
.IP
n=0: does the same as \fB-nodragging.\fR (all screen polling
is suspended if a mouse button is pressed.)
.IP
n=1: was the original scheme used to about Jan 2004:
it basically just skips \fB-input_skip\fR keyboard or pointer
events before repolling the screen.
.IP
n=2 is an improved scheme: by watching the current rate
of input events it tries to detect if it should try to
"eat" additional pointer events before continuing.
.IP
n=3 is basically a dynamic \fB-nodragging\fR mode: it detects
when the mouse motion has paused and then refreshes
the display.
.IP
n=4 attempts to measures network rates and latency,
the video card read rate, and how many tiles have been
changed on the screen.  From this, it aggressively tries
to push screen "frames" when it decides it has enough
resources to do so.  NOT FINISHED.
.IP
The default n is 2. Note that modes 2, 3, 4 will skip
\fB-input_skip\fR keyboard events (but it will not count
pointer events).  Also note that these modes are not
available in \fB-threads\fR mode which has its own pointer
event handling mechanism.
.IP
To try out the different pointer modes to see which
one gives the best response for your usage, it is
convenient to use the remote control function, for
example "x11vnc \fB-R\fR pm:4" or the tcl/tk gui (Tuning ->
pointer_mode -> n).
.PP
\fB-input_skip\fR \fIn\fR
.IP
For the pointer handling when non-threaded: try to
read n user input events before scanning display. n < 0
means to act as though there is always user input.
Default: 10
.PP
\fB-speeds\fR \fIrd,bw,lat\fR
.IP
x11vnc tries to estimate some speed parameters that
are used to optimize scheduling (e.g. \fB-pointer_mode\fR
4, \fB-wireframe,\fR \fB-scrollcopyrect)\fR and other things.
Use the \fB-speeds\fR option to set these manually.
The triple \fIrd,bw,lat\fR corresponds to video h/w
read rate in MB/sec, network bandwidth to clients in
KB/sec, and network latency to clients in milliseconds,
respectively.  If a value is left blank, e.g. "-speeds
,100,15", then the internal scheme is used to estimate
the empty value(s).
.IP
Typical PC video cards have read rates of 5-10 MB/sec.
If the framebuffer is in main memory instead of video
h/w (e.g. SunRay, shadowfb, dummy driver, Xvfb), the
read rate may be much faster.  "x11perf \fB-getimage500"\fR
can be used to get a lower bound (remember to factor
in the bytes per pixel).  It is up to you to estimate
the network bandwith and latency to clients.  For the
latency the 
.IR ping (1)
command can be used.
.IP
For convenience there are some aliases provided,
e.g. "\fB-speeds\fR \fImodem\fR".  The aliases are: "modem" for
6,4,200; "dsl" for 6,100,50; and "lan" for 6,5000,1
.PP
\fB-wmdt\fR \fIstring\fR
.IP
For some features, e.g. \fB-wireframe\fR and \fB-scrollcopyrect,\fR
x11vnc has to work around issues for certain window
managers or desktops (currently kde and xfce).
By default it tries to guess which one, but it can
guess incorrectly.  Use this option to indicate which
wm/dt.  \fIstring\fR can be "gnome", "kde", "cde",
"xfce", or "root" (classic X wm).  Anything else
is interpreted as "root".
.PP
\fB-debug_pointer\fR
.IP
Print debugging output for every pointer event.
.PP
\fB-debug_keyboard\fR
.IP
Print debugging output for every keyboard event.
.PP
Same as \fB-dp\fR and \fB-dk,\fR respectively.  Use multiple
times for more output.
.PP
\fB-defer\fR \fItime\fR
.IP
Time in ms to wait for updates before sending to client
(deferUpdateTime)  Default: 30
.PP
\fB-wait\fR \fItime\fR
.IP
Time in ms to pause between screen polls.  Used to cut
down on load.  Default: 30
.PP
\fB-wait_ui\fR \fIfactor\fR
.IP
Factor by which to cut the \fB-wait\fR time if there
has been recent user input (pointer or keyboard).
Improves response, but increases the load whenever you
are moving the mouse or typing.  Default: 2.00
.PP
\fB-nowait_bog\fR
.IP
Do not detect if the screen polling is "bogging down"
and sleep more.  Some activities with no user input can
slow things down a lot: consider a large terminal window
with a long build running in it continously streaming
text output.  By default x11vnc will try to detect this
(3 screen polls in a row each longer than 0.25 sec with
no user input), and sleep up to 1.5 secs to let things
"catch up".  Use this option to disable that detection.
.PP
\fB-slow_fb\fR \fItime\fR
.IP
Floating point time in seconds delay all screen polling.
For special purpose usage where a low frame rate is
acceptable and desirable, but you want the user input
processed at the normal rate so you cannot use \fB-wait.\fR
.PP
\fB-readtimeout\fR \fIn\fR
.IP
Set libvncserver rfbMaxClientWait to n seconds. On
slow links that take a long time to paint the first
screen libvncserver may hit the timeout and drop the
connection.  Default: 20 seconds.
.PP
\fB-nap,\fR \fB-nonap\fR
.IP
Monitor activity and if it is low take longer naps
between screen polls to really cut down load when idle.
Default: take naps
.PP
\fB-sb\fR \fItime\fR
.IP
Time in seconds after NO activity (e.g. screen blank)
to really throttle down the screen polls (i.e. sleep
for about 1.5 secs). Use 0 to disable.  Default: 60
.PP
\fB-nofbpm,\fR \fB-fbpm\fR
.IP
If the system supports the FBPM (Frame Buffer Power
Management) extension (i.e. some Sun systems), then
prevent the video h/w from going into a reduced power
state when VNC clients are connected.
.IP
FBPM capable video h/w save energy when the workstation
is idle by going into low power states (similar to DPMS
for monitors).  This interferes with x11vnc's polling
of the framebuffer data.
.IP
"\fB-nofbpm\fR" means prevent FBPM low power states whenever
VNC clients are connected, while "\fB-fbpm\fR" means to not
monitor the FBPM state at all.  See the 
.IR xset (1)
manpage
for details.  \fB-nofbpm\fR is basically the same as running
"xset fbpm force on" periodically.  Default: \fB-fbpm\fR
.PP
\fB-noxdamage\fR
.IP
Do not use the X DAMAGE extension to detect framebuffer
changes even if it is available.  Use \fB-xdamage\fR if your
default is to have it off.
.IP
x11vnc's use of the DAMAGE extension: 1) significantly
reduces the load when the screen is not changing much,
and 2) detects changed areas (small ones by default)
more quickly.
.IP
Currently the DAMAGE extension is overly conservative
and often reports large areas (e.g. a whole terminal
or browser window) as damaged even though the actual
changed region is much smaller (sometimes just a few
pixels).  So heuristics were introduced to skip large
areas and use the damage rectangles only as "hints"
for the traditional scanline polling.  The following
tuning parameters are introduced to adjust this
behavior:
.PP
\fB-xd_area\fR \fIA\fR
.IP
Set the largest DAMAGE rectangle area \fIA\fR (in
pixels: width * height) to trust as truly damaged:
the rectangle will be copied from the framebuffer
(slow) no matter what.  Set to zero to trust *all*
rectangles. Default: 20000
.PP
\fB-xd_mem\fR \fIf\fR
.IP
Set how long DAMAGE rectangles should be "remembered",
\fIf\fR is a floating point number and is in units of the
scanline repeat cycle time (32 iterations).  The default
(1.0) should give no painting problems. Increase it if
there are problems or decrease it to live on the edge
(perhaps useful on a slow machine).
.PP
\fB-sigpipe\fR \fIstring\fR
.IP
Broken pipe (SIGPIPE) handling.  \fIstring\fR can be
"ignore" or "exit".  For "ignore" libvncserver
will handle the abrupt loss of a client and continue,
for "exit" x11vnc will cleanup and exit at the 1st
broken connection.  Default: "ignore".  This option
is obsolete.
.PP
\fB-threads,\fR \fB-nothreads\fR
.IP
Whether or not to use the threaded libvncserver
algorithm [rfbRunEventLoop] if libpthread is available
Default: \fB-nothreads\fR
.PP
\fB-fs\fR \fIf\fR
.IP
If the fraction of changed tiles in a poll is greater
than f, the whole screen is updated.  Default: 0.75
.PP
\fB-gaps\fR \fIn\fR
.IP
Heuristic to fill in gaps in rows or cols of n or
less tiles.  Used to improve text paging.  Default: 4
.PP
\fB-grow\fR \fIn\fR
.IP
Heuristic to grow islands of changed tiles n or wider
by checking the tile near the boundary.  Default: 3
.PP
\fB-fuzz\fR \fIn\fR
.IP
Tolerance in pixels to mark a tiles edges as changed.
Default: 2
.PP
\fB-debug_tiles\fR
.IP
Print debugging output for tiles, fb updates, etc.
.PP
\fB-snapfb\fR
.IP
Instead of polling the X display framebuffer (fb) for
changes, periodically copy all of X display fb into main
memory and examine that copy for changes.  Under some
circumstances this will improve interactive response,
or at least make things look smoother, but in others
(most!) it will make the response worse.  If the video
h/w fb is such that reading small tiles is very slow
this mode could help.  To keep the "framerate" up
the screen size x bpp cannot be too large.  Note that
this mode is very wasteful of memory I/O resources
(it makes full screen copies even if nothing changes).
It may be of use in video capture-like applications,
or where window tearing is a problem.
.PP
\fB-rawfb\fR \fIstring\fR
.IP
Experimental option, instead of polling X, poll the
memory object specified in \fIstring\fR.  For shared
memory segments it is of the form: "shm:N@WxHxB"
which specifies a shmid N and framebuffer Width, Height,
and Bits per pixel.  To memory map 
.IR mmap (2)
a file use:
"map:/path/to/a/file@WxHxB".  If there is trouble
with mmap, use  "file:/..." for slower 
.IR lseek (2)
based reading.  If you do not supply a type "map"
is assumed if the file exists.
.IP
If string is "setup:cmd", then the command "cmd"
is run and the first line from it is read and used
as \fIstring\fR.  This allows initializing the device,
determining WxHxB, etc. These are often done as root
so take care.
.IP
Optional suffixes are ":R/G/B" and "+O" to specify
red, green, and blue masks and an offset into the
memory object.  If the masks are not provided x11vnc
guesses them based on the bpp.
.IP
Examples:
.IP
\fB-rawfb\fR shm:210337933@800x600x32:ff/ff00/ff0000
.IP
\fB-rawfb\fR map:/dev/fb0@1024x768x32
.IP
\fB-rawfb\fR map:/tmp/Xvfb_screen0@640x480x8+3232
.IP
\fB-rawfb\fR file:/tmp/my.pnm@250x200x24+37
.IP
(see 
.IR ipcs (1)
and 
.IR fbset (1)
for the first two examples)
.IP
All user input is discarded by default (but see the
\fB-pipeinput\fR option).  Most of the X11 (screen, keyboard,
mouse) options do not make sense and many will cause
this mode to crash, so please think twice before
setting/changing them.
.IP
If you don't want x11vnc to close the X DISPLAY in
rawfb mode, then capitalize the prefix, SHM:, MAP:,
FILE:   Keeping the display open enables the default
remote-control channel, which could be useful.  Also,
if you also specify \fB-noviewonly,\fR then the mouse and
keyboard input are STILL sent to the X display, this
usage should be very rare, i.e. doing something strange
with /dev/fb0.
.PP
\fB-pipeinput\fR \fIcmd\fR
.IP
Another experimental option: it lets you supply an
external command in \fIcmd\fR that x11vnc will pipe
all of the user input events to in a simple format.
In \fB-pipeinput\fR mode by default x11vnc will not process
any of the user input events.  If you prefix \fIcmd\fR
with "tee:" it will both send them to the pipe
command and process them.  For a description of the
format run "\fB-pipeinput\fR \fItee:/bin/cat\fR".  Another prefix
is "reopen" which means to reopen pipe if it exits.
Separate multiple prefixes with commas.
.IP
In combination with \fB-rawfb\fR one might be able to
do amusing things (e.g. control non-X devices).
To facilitate this, if \fB-rawfb\fR is in effect then the
value is stored in X11VNC_RAWFB_STR for the pipe command
to use if it wants. Do 'env | grep X11VNC' for more.
.PP
\fB-gui\fR \fI[gui-opts]\fR
.IP
Start up a simple tcl/tk gui based on the the remote
control options \fB-remote/-query\fR described below.
Requires the "wish" program to be installed on the
machine.  "gui-opts" is not required: the default
is to start up both the full gui and x11vnc with the
gui showing up on the X display in the environment
variable DISPLAY.
.IP
"gui-opts" can be a comma separated list of items.
Currently there are these types of items: 1) a gui
mode, a 2) gui "simplicity", 3) the X display the
gui should display on, 4) a "tray" or "icon" mode,
and 5) a gui geometry.
.IP
1) The gui mode can be "start", "conn", or "wait"
"start" is the default mode above and is not required.
"conn" means do not automatically start up x11vnc,
but instead just try to connect to an existing x11vnc
process.  "wait" means just start the gui and nothing
else (you will later instruct the gui to start x11vnc
or connect to an existing one.)
.IP
2) The gui simplicity is off by default (a power-user
gui with all options is presented) To start with
something less daunting supply the string "simple"
("ez" is an alias for this).  Once the gui is
started you can toggle between the two with "Misc ->
simple_gui".
.IP
3) Note the possible confusion regarding the potentially
two different X displays: x11vnc polls one, but you
may want the gui to appear on another.  For example, if
you ssh in and x11vnc is not running yet you may want
the gui to come back to you via your ssh redirected X
display (e.g. localhost:10).
.IP
If you do not specify a gui X display in "gui-opts"
then the DISPLAY environment variable and \fB-display\fR
option are tried (in that order).  Regarding the x11vnc
X display the gui will try to communication with, it
first tries \fB-display\fR and then DISPLAY.  For example,
"x11vnc \fB-display\fR :0 \fB-gui\fR otherhost:0", will remote
control an x11vnc polling :0 and display the gui on
otherhost:0 The "tray/icon" mode below reverses this
preference, preferring to display on the x11vnc display.
.IP
4) When "tray" or "icon" is specified, the gui
presents itself as a small icon with behavior typical
of a "system tray" or "dock applet".  The color
of the icon indicates status (connected clients) and
there is also a balloon status.  Clicking on the icon
gives a menu from which properties, etc, can be set and
the full gui is available under "Advanced".  To be
fully functional, the gui mode should be "start"
(the default).
.IP
For "icon" the gui just a small standalone window.
For "tray" it will attempt to embed itself in the
"system tray" if possible. If "=setpass" is appended then
at startup the X11 user will be prompted to set the
VNC session password.  If =<hexnumber> is appended
that icon will attempt to embed itself in the window
given by hexnumber.  Use =noadvanced to disable the
full gui. (To supply more than one, use "+" sign).
E.g. \fB-gui\fR tray=setpass and \fB-gui\fR icon=0x3600028
.IP
Other modes: "full", the default and need not be
specified.  "\fB-gui\fR \fInone\fR", do not show a gui, useful
to override a ~/.x11vncrc setting, etc.
.IP
5) When "geom=+X+Y" is specified, that geometry
is passed to the gui toplevel.  This is the icon in
icon/tray mode, or the full gui otherwise.  You can
also specify width and height, i.e. WxH+X+Y, but it
is not recommended.  In "tray" mode the geometry is
ignored unless the system tray manager does not seem
to be running.  One could imagine using something like
"\fB-gui\fR \fItray,geom=+4000+4000\fR" with a display manager
to keep the gui invisible until someone logs in...
.IP
More icon tricks, "icon=minimal" gives an icon just
with the VNC display number.  You can also set the font
with "iconfont=...".  The following could be useful:
"\fB-gui\fR \fIicon=minimal,iconfont=5x8,geom=24x10+0-0\fR"
.IP
General examples of the \fB-gui\fR option: "x11vnc \fB-gui",\fR
"x11vnc \fB-gui\fR ez" "x11vnc \fB-gui\fR localhost:10",
"x11vnc \fB-gui\fR conn,host:0", "x11vnc \fB-gui\fR tray,ez"
"x11vnc \fB-gui\fR tray=setpass"
.IP
If you do not intend to start x11vnc from the gui
(i.e. just remote control an existing one), then the
gui process can run on a different machine from the
x11vnc server as long as X permissions, etc. permit
communication between the two.
.PP
\fB-remote\fR \fIcommand\fR
.IP
Remotely control some aspects of an already running
x11vnc server.  "\fB-R\fR" and "\fB-r\fR" are aliases for
"\fB-remote\fR".  After the remote control command is
sent to the running server the 'x11vnc \fB-remote\fR ...'
command exits.  You can often use the \fB-query\fR command
(see below) to see if the x11vnc server processed your
\fB-remote\fR command.
.IP
The default communication channel is that of X
properties (specifically X11VNC_REMOTE), and so this
command must be run with correct settings for DISPLAY
and possibly XAUTHORITY to connect to the X server
and set the property.  Alternatively, use the \fB-display\fR
and \fB-auth\fR options to set them to the correct values.
The running server cannot use the \fB-novncconnect\fR option
because that disables the communication channel.
See below for alternate channels.
.IP
For example: 'x11vnc \fB-remote\fR stop' (which is the same as
\'x11vnc \fB-R\fR stop') will close down the x11vnc server.
\'x11vnc \fB-R\fR shared' will enable shared connections, and
\'x11vnc \fB-R\fR scale:3/4' will rescale the desktop.
.IP
.IP
The following \fB-remote/-R\fR commands are supported:
.IP
stop            terminate the server, same as "quit"
"exit" or "shutdown".
.IP
ping            see if the x11vnc server responds.
Return is: ans=ping:<xdisplay>
.IP
blacken         try to push a black fb update to all
clients (due to timings a client
could miss it). Same as "zero", also
"zero:x1,y1,x2,y2" for a rectangle.
.IP
refresh         send the entire fb to all clients.
.IP
reset           recreate the fb, polling memory, etc.
.IP
id:windowid     set \fB-id\fR window to "windowid". empty
or "root" to go back to root window
.IP
sid:windowid    set \fB-sid\fR window to "windowid"
.IP
waitmapped      wait until subwin is mapped.
.IP
nowaitmapped    do not wait until subwin is mapped.
.IP
clip:WxH+X+Y    set \fB-clip\fR mode to "WxH+X+Y"
.IP
flashcmap       enable  \fB-flashcmap\fR mode.
.IP
noflashcmap     disable \fB-flashcmap\fR mode.
.IP
shiftcmap:n     set \fB-shiftcmap\fR to n.
.IP
notruecolor     enable  \fB-notruecolor\fR mode.
.IP
truecolor       disable \fB-notruecolor\fR mode.
.IP
overlay         enable  \fB-overlay\fR mode (if applicable).
.IP
nooverlay       disable \fB-overlay\fR mode.
.IP
overlay_cursor  in \fB-overlay\fR mode, enable cursor drawing.
.IP
overlay_nocursor disable cursor drawing. same as
nooverlay_cursor.
.IP
8to24           enable  \fB-8to24\fR mode (if applicable).
.IP
no8to24         disable \fB-8to24\fR mode.
.IP
8to24_opts:str  set the \fB-8to24\fR opts to "str".
.IP
visual:vis      set \fB-visual\fR to "vis"
.IP
scale:frac      set \fB-scale\fR to "frac"
.IP
scale_cursor:f  set \fB-scale_cursor\fR to "f"
.IP
viewonly        enable  \fB-viewonly\fR mode.
.IP
noviewonly      disable \fB-viewonly\fR mode.
.IP
shared          enable  \fB-shared\fR mode.
.IP
noshared        disable \fB-shared\fR mode.
.IP
forever         enable  \fB-forever\fR mode.
.IP
noforever       disable \fB-forever\fR mode.
.IP
timeout:n       reset \fB-timeout\fR to n, if there are
currently no clients, exit unless one
connects in the next n secs.
.IP
filexfer        enable  filetransfer for new clients.
.IP
nofilexfer      disable filetransfer for new clients.
.IP
http            enable  http client connections.
.IP
nohttp          disable http client connections.
.IP
deny            deny any new connections, same as "lock"
.IP
nodeny          allow new connections, same as "unlock"
.IP
connect:host    do reverse connection to host, "host"
may be a comma separated list of hosts
or host:ports.  See \fB-connect.\fR  Passwords
required as with fwd connections.
See X11VNC_REVERSE_CONNECTION_NO_AUTH=1
.IP
disconnect:host disconnect any clients from "host"
same as "close:host".  Use host
"all" to close all current clients.
If you know the client internal hex ID,
e.g. 0x3 (returned by "\fB-query\fR \fIclients\fR"
and RFB_CLIENT_ID) you can use that too.
.IP
allowonce:host  For the next connection only, allow
connection from "host".
.IP
allow:hostlist  set \fB-allow\fR list to (comma separated)
"hostlist". See \fB-allow\fR and \fB-localhost.\fR
Do not use with \fB-allow\fR /path/to/file
Use "+host" to add a single host, and
use "\fB-host\fR" to delete a single host
.IP
localhost       enable  \fB-localhost\fR mode
.IP
nolocalhost     disable \fB-localhost\fR mode
.IP
listen:str      set \fB-listen\fR to str, empty to disable.
.IP
nolookup        enable  \fB-nolookup\fR mode.
.IP
lookup          disable \fB-nolookup\fR mode.
.IP
input:str       set \fB-input\fR to "str", empty to disable.
.IP
client_input:str set the K, M, B \fB-input\fR on a per-client
basis.  select which client as for
disconnect, e.g. client_input:host:MB
or client_input:0x2:K
.IP
accept:cmd      set \fB-accept\fR "cmd" (empty to disable).
.IP
afteraccept:cmd set \fB-afteraccept\fR (empty to disable).
.IP
gone:cmd        set \fB-gone\fR "cmd" (empty to disable).
.IP
noshm           enable  \fB-noshm\fR mode.
.IP
shm             disable \fB-noshm\fR mode (i.e. use shm).
.IP
flipbyteorder   enable \fB-flipbyteorder\fR mode, you may need
to set noshm for this to do something.
.IP
noflipbyteorder disable \fB-flipbyteorder\fR mode.
.IP
onetile         enable  \fB-onetile\fR mode. (you may need to
set shm for this to do something)
.IP
noonetile       disable \fB-onetile\fR mode.
.IP
solid           enable  \fB-solid\fR mode
.IP
nosolid         disable \fB-solid\fR mode.
.IP
solid_color:color set \fB-solid\fR color (and apply it).
.IP
blackout:str    set \fB-blackout\fR "str" (empty to disable).
See \fB-blackout\fR for the form of "str"
(basically: WxH+X+Y,...)
Use "+WxH+X+Y" to append a single
rectangle use "-WxH+X+Y" to delete one
.IP
xinerama        enable  \fB-xinerama\fR mode. (if applicable)
.IP
noxinerama      disable \fB-xinerama\fR mode.
.IP
xtrap           enable  \fB-xtrap\fR input mode(if applicable)
.IP
noxtrap         disable \fB-xtrap\fR input mode.
.IP
xrandr          enable  \fB-xrandr\fR mode. (if applicable)
.IP
noxrandr        disable \fB-xrandr\fR mode.
.IP
xrandr_mode:mode set the \fB-xrandr\fR mode to "mode".
.IP
padgeom:WxH     set \fB-padgeom\fR to WxH (empty to disable)
If WxH is "force" or "do" the padded
geometry fb is immediately applied.
.IP
quiet           enable  \fB-quiet\fR mode.
.IP
noquiet         disable \fB-quiet\fR mode.
.IP
modtweak        enable  \fB-modtweak\fR mode.
.IP
nomodtweak      enable  \fB-nomodtweak\fR mode.
.IP
xkb             enable  \fB-xkb\fR modtweak mode.
.IP
noxkb           disable \fB-xkb\fR modtweak mode.
.IP
skip_keycodes:str enable \fB-xkb\fR \fB-skip_keycodes\fR "str".
.IP
sloppy_keys     enable  \fB-sloppy_keys\fR mode.
.IP
nosloppy_keys   disable \fB-sloppy_keys\fR mode.
.IP
skip_dups       enable  \fB-skip_dups\fR mode.
.IP
noskip_dups     disable \fB-skip_dups\fR mode.
.IP
add_keysyms     enable \fB-add_keysyms\fR mode.
.IP
noadd_keysyms   stop adding keysyms. those added will
still be removed at exit.
.IP
clear_mods      enable  \fB-clear_mods\fR mode and clear them.
.IP
noclear_mods    disable \fB-clear_mods\fR mode.
.IP
clear_keys      enable  \fB-clear_keys\fR mode and clear them.
.IP
noclear_keys    disable \fB-clear_keys\fR mode.
.IP
remap:str       set \fB-remap\fR "str" (empty to disable).
See \fB-remap\fR for the form of "str"
(basically: key1-key2,key3-key4,...)
Use "+key1-key2" to append a single
keymapping, use "-key1-key2" to delete.
.IP
norepeat        enable  \fB-norepeat\fR mode.
.IP
repeat          disable \fB-norepeat\fR mode.
.IP
nofb            enable  \fB-nofb\fR mode.
.IP
fb              disable \fB-nofb\fR mode.
.IP
bell            enable  bell (if supported).
.IP
nobell          disable bell.
.IP
nosel           enable  \fB-nosel\fR mode.
.IP
sel             disable \fB-nosel\fR mode.
.IP
noprimary       enable  \fB-noprimary\fR mode.
.IP
primary         disable \fB-noprimary\fR mode.
.IP
nosetprimary    enable  \fB-nosetprimary\fR mode.
.IP
setprimary      disable \fB-nosetprimary\fR mode.
.IP
noclipboard     enable  \fB-noclipboard\fR mode.
.IP
clipboard       disable \fB-noclipboard\fR mode.
.IP
nosetclipboard  enable  \fB-nosetclipboard\fR mode.
.IP
setclipboard    disable \fB-nosetclipboard\fR mode.
.IP
seldir:str      set \fB-seldir\fR to "str"
.IP
cursor:mode     enable  \fB-cursor\fR "mode".
.IP
show_cursor     enable  showing a cursor.
.IP
noshow_cursor   disable showing a cursor. (same as
"nocursor")
.IP
arrow:n         set \fB-arrow\fR to alternate n.
.IP
xfixes          enable  xfixes cursor shape mode.
.IP
noxfixes        disable xfixes cursor shape mode.
.IP
alphacut:n      set \fB-alphacut\fR to n.
.IP
alphafrac:f     set \fB-alphafrac\fR to f.
.IP
alpharemove     enable  \fB-alpharemove\fR mode.
.IP
noalpharemove   disable \fB-alpharemove\fR mode.
.IP
alphablend      disable \fB-noalphablend\fR mode.
.IP
noalphablend    enable  \fB-noalphablend\fR mode.
.IP
cursorshape     disable \fB-nocursorshape\fR mode.
.IP
nocursorshape   enable  \fB-nocursorshape\fR mode.
.IP
cursorpos       disable \fB-nocursorpos\fR mode.
.IP
nocursorpos     enable  \fB-nocursorpos\fR mode.
.IP
xwarp           enable  \fB-xwarppointer\fR mode.
.IP
noxwarp         disable \fB-xwarppointer\fR mode.
.IP
buttonmap:str   set \fB-buttonmap\fR "str", empty to disable
.IP
dragging        disable \fB-nodragging\fR mode.
.IP
nodragging      enable  \fB-nodragging\fR mode.
.IP
wireframe       enable  \fB-wireframe\fR mode. same as "wf"
.IP
nowireframe     disable \fB-wireframe\fR mode. same as "nowf"
.IP
wireframe:str   enable  \fB-wireframe\fR mode string.
.IP
wireframe_mode:str enable  \fB-wireframe\fR mode string.
.IP
wirecopyrect:str set \fB-wirecopyrect\fR string. same as "wcr:"
.IP
scrollcopyrect:str set \fB-scrollcopyrect\fR string. same "scr"
.IP
noscrollcopyrect disable \fB-scrollcopyrect__mode_.\fR "noscr"
.IP
scr_area:n      set \fB-scr_area\fR to n
.IP
scr_skip:list   set \fB-scr_skip\fR to "list"
.IP
scr_inc:list    set \fB-scr_inc\fR to "list"
.IP
scr_keys:list   set \fB-scr_keys\fR to "list"
.IP
scr_term:list   set \fB-scr_term\fR to "list"
.IP
scr_keyrepeat:str set \fB-scr_keyrepeat\fR to "str"
.IP
scr_parms:str   set \fB-scr_parms\fR parameters.
.IP
fixscreen:str   set \fB-fixscreen\fR to "str".
.IP
noxrecord       disable all use of RECORD extension.
.IP
xrecord         enable  use of RECORD extension.
.IP
reset_record    reset RECORD extension (if avail.)
.IP
pointer_mode:n  set \fB-pointer_mode\fR to n. same as "pm"
.IP
input_skip:n    set \fB-input_skip\fR to n.
.IP
speeds:str      set \fB-speeds\fR to str.
.IP
wmdt:str        set \fB-wmdt\fR to str.
.IP
debug_pointer   enable  \fB-debug_pointer,\fR same as "dp"
.IP
nodebug_pointer disable \fB-debug_pointer,\fR same as "nodp"
.IP
debug_keyboard   enable  \fB-debug_keyboard,\fR same as "dk"
.IP
nodebug_keyboard disable \fB-debug_keyboard,\fR same as "nodk"
.IP
defer:n         set \fB-defer\fR to n ms,same as deferupdate:n
.IP
wait:n          set \fB-wait\fR to n ms.
.IP
wait_ui:f       set \fB-wait_ui\fR factor to f.
.IP
wait_bog        disable \fB-nowait_bog\fR mode.
.IP
nowait_bog      enable  \fB-nowait_bog\fR mode.
.IP
slow_fb:f       set \fB-slow_fb\fR to f seconds.
.IP
readtimeout:n   set read timeout to n seconds.
.IP
nap             enable  \fB-nap\fR mode.
.IP
nonap           disable \fB-nap\fR mode.
.IP
sb:n            set \fB-sb\fR to n s, same as screen_blank:n
.IP
fbpm            disable \fB-nofbpm\fR mode.
.IP
nofbpm          enable  \fB-nofbpm\fR mode.
.IP
xdamage         enable  xdamage polling hints.
.IP
noxdamage       disable xdamage polling hints.
.IP
xd_area:A       set \fB-xd_area\fR max pixel area to "A"
.IP
xd_mem:f        set \fB-xd_mem\fR remembrance to "f"
.IP
fs:frac         set \fB-fs\fR fraction to "frac", e.g. 0.5
.IP
gaps:n          set \fB-gaps\fR to n.
.IP
grow:n          set \fB-grow\fR to n.
.IP
fuzz:n          set \fB-fuzz\fR to n.
.IP
snapfb          enable  \fB-snapfb\fR mode.
.IP
nosnapfb        disable \fB-snapfb\fR mode.
.IP
rawfb:str       set \fB-rawfb\fR mode to "str".
.IP
progressive:n   set libvncserver \fB-progressive\fR slice
height parameter to n.
.IP
desktop:str     set \fB-desktop\fR name to str for new clients.
.IP
rfbport:n       set \fB-rfbport\fR to n.
.IP
httpport:n      set \fB-httpport\fR to n.
.IP
httpdir:dir     set \fB-httpdir\fR to dir (and enable http).
.IP
enablehttpproxy   enable  \fB-enablehttpproxy\fR mode.
.IP
noenablehttpproxy disable \fB-enablehttpproxy\fR mode.
.IP
alwaysshared     enable  \fB-alwaysshared\fR mode.
.IP
noalwaysshared   disable \fB-alwaysshared\fR mode.
(may interfere with other options)
.IP
nevershared      enable  \fB-nevershared\fR mode.
.IP
nonevershared    disable \fB-nevershared\fR mode.
(may interfere with other options)
.IP
dontdisconnect   enable  \fB-dontdisconnect\fR mode.
.IP
nodontdisconnect disable \fB-dontdisconnect\fR mode.
(may interfere with other options)
.IP
debug_xevents   enable  debugging X events.
.IP
nodebug_xevents disable debugging X events.
.IP
debug_xdamage   enable  debugging X DAMAGE mechanism.
.IP
nodebug_xdamage disable debugging X DAMAGE mechanism.
.IP
debug_wireframe enable   debugging wireframe mechanism.
.IP
nodebug_wireframe disable debugging wireframe mechanism.
.IP
debug_scroll    enable  debugging scrollcopy mechanism.
.IP
nodebug_scroll  disable debugging scrollcopy mechanism.
.IP
debug_tiles     enable  \fB-debug_tiles\fR
.IP
nodebug_tiles   disable \fB-debug_tiles\fR
.IP
debug_grabs     enable  \fB-debug_grabs\fR
.IP
nodebug_grabs   disable \fB-debug_grabs\fR
.IP
debug_sel       enable  \fB-debug_sel\fR
.IP
nodebug_sel     disable \fB-debug_sel\fR
.IP
dbg             enable  \fB-dbg\fR crash shell
.IP
nodbg           disable \fB-dbg\fR crash shell
.IP
.IP
noremote        disable the \fB-remote\fR command processing,
it cannot be turned back on.
.IP
.IP
The 
.IR vncconnect (1)
command from standard VNC
.IP
distributions may also be used if string is prefixed
.IP
with "cmd=" E.g. 'vncconnect cmd=stop'.  Under some
.IP
circumstances 
.IR xprop (1)
can used if it supports \fB-set\fR
.IP
(see the FAQ).
.IP
.IP
If "\fB-connect\fR \fI/path/to/file\fR" has been supplied to the
.IP
running x11vnc server then that file can be used as a
.IP
communication channel (this is the only way to remote
.IP
control one of many x11vnc's polling the same X display)
.IP
Simply run: 'x11vnc \fB-connect\fR /path/to/file \fB-remote\fR ...'
.IP
or you can directly write to the file via something
.IP
like: "echo cmd=stop > /path/to/file", etc.
.PP
\fB-query\fR \fIvariable\fR
.IP
Like \fB-remote,\fR except just query the value of
\fIvariable\fR.  "\fB-Q\fR" is an alias for "\fB-query\fR".
Multiple queries can be done by separating variables
by commas, e.g. \fB-query\fR var1,var2. The results come
back in the form ans=var1:value1,ans=var2:value2,...
to the standard output.  If a variable is read-only,
it comes back with prefix "aro=" instead of "ans=".
.IP
Some \fB-remote\fR commands are pure actions that do not make
sense as variables, e.g. "stop" or "disconnect", in
these cases the value returned is "N/A".  To direct a
query straight to the X11VNC_REMOTE property or connect
file use "qry=..." instead of "cmd=..."
.IP
Here is the current list of "variables" that can
be supplied to the \fB-query\fR command. This includes the
"N/A" ones that return no useful info.  For variables
names that do not correspond to an x11vnc option or
remote command, we hope the name makes it obvious what
the returned value corresponds to (hint: the ext_*
variables correspond to the presence of X extensions):
.IP
ans= stop quit exit shutdown ping blacken zero
refresh reset close disconnect id sid waitmapped
nowaitmapped clip flashcmap noflashcmap shiftcmap
truecolor notruecolor overlay nooverlay overlay_cursor
overlay_yescursor nooverlay_nocursor nooverlay_cursor
nooverlay_yescursor overlay_nocursor 8to24 no8to24
8to24_opts visual scale scale_cursor viewonly noviewonly
shared noshared forever noforever once timeout filexfer
nofilexfer deny lock nodeny unlock connect allowonce
allow localhost nolocalhost listen lookup nolookup
accept afteraccept gone shm noshm flipbyteorder
noflipbyteorder onetile noonetile solid_color
solid nosolid blackout xinerama noxinerama xtrap
noxtrap xrandr noxrandr xrandr_mode padgeom quiet q
noquiet modtweak nomodtweak xkb noxkb skip_keycodes
sloppy_keys nosloppy_keys skip_dups noskip_dups
add_keysyms noadd_keysyms clear_mods noclear_mods
clear_keys noclear_keys remap repeat norepeat fb nofb
bell nobell sel nosel primary noprimary setprimary
nosetprimary clipboard noclipboard setclipboard
nosetclipboard seldir cursorshape nocursorshape
cursorpos nocursorpos cursor show_cursor noshow_cursor
nocursor arrow xfixes noxfixes xdamage noxdamage
xd_area xd_mem alphacut alphafrac alpharemove
noalpharemove alphablend noalphablend xwarppointer
xwarp noxwarppointer noxwarp buttonmap dragging
nodragging wireframe_mode wireframe wf nowireframe
nowf wirecopyrect wcr nowirecopyrect nowcr scr_area
scr_skip scr_inc scr_keys scr_term scr_keyrepeat
scr_parms scrollcopyrect scr noscrollcopyrect noscr
fixscreen noxrecord xrecord reset_record pointer_mode
pm input_skip input client_input speeds wmdt
debug_pointer dp nodebug_pointer nodp debug_keyboard
dk nodebug_keyboard nodk deferupdate defer wait_ui
wait_bog nowait_bog slow_fb wait readtimeout nap nonap
sb screen_blank fbpm nofbpm fs gaps grow fuzz snapfb
nosnapfb rawfb progressive rfbport http nohttp httpport
httpdir enablehttpproxy noenablehttpproxy alwaysshared
noalwaysshared nevershared noalwaysshared dontdisconnect
nodontdisconnect desktop debug_xevents nodebug_xevents
debug_xevents debug_xdamage nodebug_xdamage
debug_xdamage debug_wireframe nodebug_wireframe
debug_wireframe debug_scroll nodebug_scroll debug_scroll
debug_tiles dbt nodebug_tiles nodbt debug_tiles
debug_grabs nodebug_grabs debug_sel nodebug_sel dbg
nodbg noremote
.IP
aro=  noop display vncdisplay desktopname guess_desktop
http_url auth xauth users rootshift clipshift
scale_str scaled_x scaled_y scale_numer scale_denom
scale_fac scaling_blend scaling_nomult4 scaling_pad
scaling_interpolate inetd privremote unsafe safer nocmds
passwdfile unixpw unixpw_nis unixpw_list ssl ssl_pem
sslverify stunnel stunnel_pem https usepw using_shm
logfile o flag rc norc h help V version lastmod bg
sigpipe threads readrate netrate netlatency pipeinput
clients client_count pid ext_xtest ext_xtrap ext_xrecord
ext_xkb ext_xshm ext_xinerama ext_overlay ext_xfixes
ext_xdamage ext_xrandr rootwin num_buttons button_mask
mouse_x mouse_y bpp depth indexed_color dpy_x dpy_y
wdpy_x wdpy_y off_x off_y cdpy_x cdpy_y coff_x coff_y
rfbauth passwd viewpasswd
.PP
\fB-QD\fR \fIvariable\fR
.IP
Just like \fB-query\fR variable, but returns the default
value for that parameter (no running x11vnc server
is consulted)
.PP
\fB-sync\fR
.IP
By default \fB-remote\fR commands are run asynchronously, that
is, the request is posted and the program immediately
exits.  Use \fB-sync\fR to have the program wait for an
acknowledgement from the x11vnc server that command was
processed (somehow).  On the other hand \fB-query\fR requests
are always processed synchronously because they have
to wait for the answer.
.IP
Also note that if both \fB-remote\fR and \fB-query\fR requests are
supplied on the command line, the \fB-remote\fR is processed
first (synchronously: no need for \fB-sync),\fR and then
the \fB-query\fR request is processed in the normal way.
This allows for a reliable way to see if the \fB-remote\fR
command was processed by querying for any new settings.
Note however that there is timeout of a few seconds so
if the x11vnc takes longer than that to process the
requests the requestor will think that a failure has
taken place.
.PP
\fB-noremote,\fR \fB-yesremote\fR
.IP
Do not process any remote control commands or queries.
Do process remote control commands or queries.
Default: \fB-yesremote\fR
.IP
A note about security wrt remote control commands.
If someone can connect to the X display and change
the property X11VNC_REMOTE, then they can remotely
control x11vnc.  Normally access to the X display is
protected.  Note that if they can modify X11VNC_REMOTE
on the X server, they have enough permissions to also
run their own x11vnc and thus have complete control
of the desktop.  If the  "\fB-connect\fR \fI/path/to/file\fR"
channel is being used, obviously anyone who can write
to /path/to/file can remotely control x11vnc.  So be
sure to protect the X display and that file's write
permissions.  See \fB-privremote\fR below.
.IP
If you are paranoid and do not think \fB-noremote\fR is
enough, to disable the X11VNC_REMOTE property channel
completely use \fB-novncconnect,\fR or use the \fB-safer\fR option
that shuts many things off.
.PP
\fB-unsafe\fR
.IP
A few remote commands are disabled by default
(currently: id:pick, accept:<cmd>, gone:<cmd>, and
rawfb:setup:<cmd>) because they are associated with
running external programs.  If you specify \fB-unsafe,\fR then
these remote-control commands are allowed.  Note that
you can still specify these parameters on the command
line, they just cannot be invoked via remote-control.
.PP
\fB-safer\fR
.IP
Equivalent to: \fB-novncconnect\fR \fB-noremote\fR and prohibiting
\fB-gui\fR and the \fB-connect\fR file. Shuts off communcation
channels.
.PP
\fB-privremote\fR
.IP
Perform some sanity checks and disable remote-control
commands if it appears that the X DISPLAY and/or
connectfile can be accessed by other users.  Once
remote-control is disabled it cannot be turned back on.
.PP
\fB-nocmds\fR
.IP
No external commands (e.g. 
.IR system (3)
, 
.IR popen (3)
, 
.IR exec (3)
)
will be run.
.PP
\fB-deny_all\fR
.IP
For use with \fB-remote\fR nodeny: start out denying all
incoming clients until "\fB-remote\fR \fInodeny\fR" is used to
let them in.
.PP
These options are passed to libvncserver:
.PP
\fB-rfbport\fR \fIport\fR
.IP
TCP port for RFB protocol
.PP
\fB-rfbwait\fR \fItime\fR
.IP
max time in ms to wait for RFB client
.PP
\fB-rfbauth\fR \fIpasswd-file\fR
.IP
use authentication on RFB protocol
(use 'storepasswd' to create a password file)
.PP
\fB-passwd\fR \fIplain-password\fR
.IP
use authentication
(use plain-password as password, USE AT YOUR RISK)
.PP
\fB-deferupdate\fR \fItime\fR
.IP
time in ms to defer updates (default 40)
.PP
\fB-deferptrupdate\fR \fItime\fR
.IP
time in ms to defer pointer updates (default none)
.PP
\fB-desktop\fR \fIname\fR
.IP
VNC desktop name (default "LibVNCServer")
.PP
\fB-alwaysshared\fR
.IP
always treat new clients as shared
.PP
\fB-nevershared\fR
.IP
never treat new clients as shared
.PP
\fB-dontdisconnect\fR
.IP
don't disconnect existing clients when a new non-shared
connection comes in (refuse new connection instead)
.PP
\fB-httpdir\fR \fIdir-path\fR
.IP
enable http server using dir-path home
.PP
\fB-httpport\fR \fIportnum\fR
.IP
use portnum for http connection
.PP
\fB-enablehttpproxy\fR
.IP
enable http proxy support
.PP
\fB-progressive\fR \fIheight\fR
.IP
enable progressive updating for slow links
.PP
\fB-listen\fR \fIipaddr\fR
.IP
listen for connections only on network interface with
addr ipaddr. '-listen localhost' and hostname work too.
.PP
libvncserver-tight-extension options:
.PP
\fB-disablefiletransfer\fR
.IP
disable file transfer
.PP
\fB-ftproot\fR \fIstring\fR
.IP
set ftp root
.SH "FILES"
.IR $HOME/.x11vncrc ,
.IR $HOME/.Xauthority
.SH "ENVIRONMENT"
.IR DISPLAY ,
.IR XAUTHORITY ,
.IR HOME
.PP
The following are set for the auxiliary commands
run by \fB-accept\fR and \fB-gone\fR:
.PP
.IR RFB_CLIENT_IP ,
.IR RFB_CLIENT_PORT ,
.IR RFB_SERVER_IP ,
.IR RFB_SERVER_PORT ,
.IR RFB_X11VNC_PID ,
.IR RFB_CLIENT_ID ,
.IR RFB_CLIENT_COUNT ,
.IR RFB_MODE
.SH "SEE ALSO"
.IR vncviewer (1),
.IR vncpasswd (1),
.IR vncconnect (1),
.IR vncserver (1),
.IR Xvnc (1),
.IR xev (1),
.IR xdpyinfo (1),
.IR xwininfo (1),
.IR xprop (1),
.IR xmodmap (1),
.IR xrandr (1),
.IR Xserver (1),
.IR xauth (1),
.IR xhost (1),
.IR Xsecurity (7),
.IR xmessage (1),
.IR XGetImage (3X11),
.IR ipcrm (1),
.IR inetd (1),
.IR xdm (1),
.IR gdm (1),
.IR kdm (1),
.IR ssh (1),
.IR stunnel (8),
.IR su (1),
.IR http://www.tightvnc.com ,
.IR http://www.realvnc.com ,
.IR http://www.karlrunge.com/x11vnc/ ,
.IR http://www.karlrunge.com/x11vnc/#faq
.SH AUTHORS
x11vnc was written by Karl J. Runge <runge@karlrunge.com>,
it is part of the LibVNCServer project <http://sf.net/projects/libvncserver>.
This manual page is based one the one written by Ludovic Drolez
<ldrolez@debian.org>, for the Debian project (both may be used by others).