Configure VNC service to allow more than 2 new simultaneous sessions

This document (3833668) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11
SUSE Linux Enterprise Server 10

Situation

GNOME desktop environment and gdm (GNOME Display Manager)
Tightvnc started through xinetd

You want to allow more than 2 new vnc sessions to your vnc server. However, after you try to establish the third new session you get an error:

ERROR: VNC server supports protocol version 3.7 (viewer 3.3)
ERROR: vncviewer: read: Connection reset by peer

Sometimes only a single VNC session is allowed at a time on a SLES 11 server

Resolution

The problem is caused by the default setting of the display manager, that allows only 2 simultaneous connections.

For SLES 10:

Edit the file /etc/opt/gnome/gdm/gdm.conf and uncomment the switch:
DisplaysPerHost=8
and put a number of displays, that you wish to display at the same time. In this case it would allow 8 sessions at the same time.
Additionally, you might want to check the
MaxSessions=
switch that controls the maximum number of open XDMCP sessions that are allowed at any point in time.
Restart the xdm service:
rcxdm stop
rcxdm start
to apply the changes.

For SLES 11:

Edit the same setting in the /etc/gdm/gdm.schemas file and restart the xdm service.

Additional Information

An rcxdm restart might not always startup the xdm service properly

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.