diff --git a/docs/man/sesman.ini.5 b/docs/man/sesman.ini.5
index e6fd0ada..ebefd120 100644
--- a/docs/man/sesman.ini.5
+++ b/docs/man/sesman.ini.5
@@ -104,6 +104,11 @@ The following parameters can be used in the \fB[Sessions]\fR section:
 .br 
 
 .TP 
+\fBX11DisplayOffset\fR=\fI<number>\fR
+Specifies the first X display number available for sesman(8).  This prevents sesman from interfering with real X11 servers.  The default is 10.
+.br
+
+.TP
 \fBMaxSessions\fR=\fI<number>\fR
 Sets the maximum number of simultaneous session on terminal server.
 .br 
diff --git a/sesman/config.c b/sesman/config.c
index 102d58e1..35f93f57 100644
--- a/sesman/config.c
+++ b/sesman/config.c
@@ -330,6 +330,7 @@ config_read_sessions(int file, struct config_sessions* se, struct list* param_n,
   list_clear(param_n);
 
   /* setting defaults */
+  se->x11_display_offset=10;
   se->max_sessions=0;
   se->max_idle_time=0;
   se->max_disc_time=0;
@@ -339,6 +340,10 @@ config_read_sessions(int file, struct config_sessions* se, struct list* param_n,
   for (i = 0; i < param_n->count; i++)
   {
     buf = (char*)list_get_item(param_n, i);
+    if (0 == g_strcasecmp(buf, SESMAN_CFG_X11DISPLAYOFFSET))
+    {
+      se->x11_display_offset = g_atoi((char*)list_get_item(param_v, i));
+    }
     if (0 == g_strcasecmp(buf, SESMAN_CFG_SESS_MAX))
     {
       se->max_sessions = g_atoi((char*)list_get_item(param_v, i));
@@ -360,6 +365,7 @@ config_read_sessions(int file, struct config_sessions* se, struct list* param_n,
   /* printing security config */
   g_printf("session configuration:\r\n");
   g_printf("\tMaxSessions:                 %i\r\n", se->max_sessions);
+  g_printf("\tX11DisplayOffset:            %i\r\n", se->x11_display_offset);
   g_printf("\tKillDisconnected:            %i\r\n", se->kill_disconnected);
   g_printf("\tIdleTimeLimit:               %i\r\n", se->max_idle_time);
   g_printf("\tDisconnectedTimeLimit:       %i\r\n", se->max_idle_time);
diff --git a/sesman/config.h b/sesman/config.h
index cfe7c65e..aad360ff 100644
--- a/sesman/config.h
+++ b/sesman/config.h
@@ -38,6 +38,7 @@
 #define SESMAN_CFG_PORT              "ListenPort"
 #define SESMAN_CFG_ENABLE_USERWM     "EnableUserWindowManager"
 #define SESMAN_CFG_USERWM            "UserWindowManager"
+#define SESMAN_CFG_X11DISPLAYOFFSET  "X11DisplayOffset"
 #define SESMAN_CFG_MAX_SESSION       "MaxSessions"
 #define SESMAN_CFG_AUTH_FILE_PATH    "AuthFilePath"
 
@@ -102,6 +103,11 @@ struct config_security
  */
 struct config_sessions
 {
+  /**
+   * @var x11_display_offset
+   * @brief X11 TCP port offset. default value: 10
+   */
+  int x11_display_offset;
   /**
    * @var max_sessions
    * @brief maximum number of allowed sessions. 0 for unlimited
diff --git a/sesman/sesman.ini b/sesman/sesman.ini
index 35c88450..35db5d1f 100644
--- a/sesman/sesman.ini
+++ b/sesman/sesman.ini
@@ -12,6 +12,7 @@ TerminalServerUsers=tsusers
 TerminalServerAdmins=tsadmins
 
 [Sessions]
+X11DisplayOffset=10
 MaxSessions=10
 KillDisconnected=0
 IdleTimeLimit=0
diff --git a/sesman/session.c b/sesman/session.c
index 1d487424..6edee0fd 100644
--- a/sesman/session.c
+++ b/sesman/session.c
@@ -252,9 +252,9 @@ session_get_aval_display_from_chain(void)
 {
   int display;
 
-  display = 10;
+  display = g_cfg->sess.x11_display_offset;
   lock_chain_acquire();
-  while ((display - 10) <= g_cfg->sess.max_sessions)
+  while ((display - g_cfg->sess.x11_display_offset) <= g_cfg->sess.max_sessions)
   {
     if (!session_is_display_in_chain(display))
     {