HOWTO: x11vnc (vnc for display :0)

[ErikTheRed]

x11vnc is very similar to vnc, except that it allows you to view display :0, the display that would currently be showing on your monitor if you were sitting at your computer.

1. Install the package

sudo aptitude install x11vnc

2. Run the following command

ps wwaux | grep auth

This command should output something like this:

root      3838 10.1  1.7  13308  8840 tty7     Ss+  15:35   2:14 /usr/bin/X -br -nolisten tcp :0 vt7 -auth /var/run/xauth/A:0-LliKdB
erik      5156  0.0  0.1   2800   752 pts/0    R+   15:57   0:00 grep auth

Note the bolded path after -auth, as you will need this for the next step

3. Add x11vnc service to xinetd

sudo nano /etc/xinetd.d/x11vnc

Enter this into the new file:

service x11vnc
{
        port            = 5900
        type            = UNLISTED
        socket_type     = stream
        protocol        = tcp
        wait            = no
        user            = root
        server          = /usr/bin/x11vnc
        server_args     = -inetd -o /var/log/x11vnc.log -display :0 -auth /var/run/xauth/A:0-LliKdB -many -bg
        disable         = no
}

Notice the bolded path, this is where you put the path you found in step 2.

4. Restart xinetd

sudo /etc/init.d/xinetd restart

5. You can now connect to display :0 from another machine by using a VNC client. For example:

sudo vncviewer vnchost:0

A lot of this is thanks to Tichondrius' great VNC HOW-TO which is here. His post on using x11vnc is on page 7 of that thread. In his HOW-TO there was an issue where the connection would drop out whenever you logged in or out, but I believe I have rectified this problem by using the new method to find the path to use with the -auth option.

Please let me know if there are any problems with this HOW-TO.

[krunge]

Hi,

Newer versions of x11vnc (might not be in ubuntu yet) support automatic
finding of the -auth authority file, and can also find both the DISPLAY and authority
file using unix username and password login. This is the FINDDISPLAY
stuff here: http://www.karlrunge.com/x11vnc/faq.html#faq-userlogin

E.g.:

server_args     = -inetd -o /var/log/x11vnc.log -svc

or -xdmsvc instead of -svc. The -find option may also be useful here.

[benfindlay]

I have been trying to get this set up, but when I type

ps wwaux | grep auth

to find the code for the -auth part, it just says

-auth /var/lib/gdm/:0.Xauth

Am I going wrong anywhere obvious?

Cheers

[benfindlay]

Just realised I have only been trying to connect via SSH. Just tried it and it will connect direct, but not through SSH. Any ideas why that is then?

[krunge]

Am I going wrong anywhere obvious?

No, that looks fine. /var/lib/gdm/:0.Xauth is where gdm(1) puts the server auth file. It's nice that the filename doesn't have a random part like the kdm and xdm servers do. Please send your entire /etc/xinetd.d/x11vnc (or equivalent) file.

Just realised I have only been trying to connect via SSH. Just tried it and it will connect direct, but not through SSH. Any ideas why that is then?

What was the full ssh command you ran, and the vncviewer command you ran? Do any errors or warnings get printed out (either by ssh, vncviewer, or in the x11vnc log file)?

[Al_maverick]

When xinetd starts I get an error in daemon.log. Any idea what it may be?

Mar 14 21:57:06 maverick xinetd[11740]: Reading included configuration file: /etc/xinetd.d/chargen [file=/etc/xinetd.conf] [line=14]
Mar 14 21:57:06 maverick xinetd[11740]: Reading included configuration file: /etc/xinetd.d/daytime [file=/etc/xinetd.d/daytime] [line=28]
Mar 14 21:57:06 maverick xinetd[11740]: Reading included configuration file: /etc/xinetd.d/discard [file=/etc/xinetd.d/discard] [line=26]
Mar 14 21:57:06 maverick xinetd[11740]: Reading included configuration file: /etc/xinetd.d/echo [file=/etc/xinetd.d/echo] [line=25]
Mar 14 21:57:06 maverick xinetd[11740]: Reading included configuration file: /etc/xinetd.d/time [file=/etc/xinetd.d/time] [line=26]
Mar 14 21:57:06 maverick xinetd[11740]: Reading included configuration file: /etc/xinetd.d/x11vnc [file=/etc/xinetd.d/x11vnc] [line=28]
Mar 14 21:57:06 maverick xinetd[11740]: removing chargen
Mar 14 21:57:06 maverick xinetd[11740]: removing chargen
Mar 14 21:57:06 maverick xinetd[11740]: removing daytime
Mar 14 21:57:06 maverick xinetd[11740]: removing daytime
Mar 14 21:57:06 maverick xinetd[11740]: removing discard
Mar 14 21:57:06 maverick xinetd[11740]: removing discard
Mar 14 21:57:06 maverick xinetd[11740]: removing echo
Mar 14 21:57:06 maverick xinetd[11740]: removing echo
Mar 14 21:57:06 maverick xinetd[11740]: removing time
Mar 14 21:57:06 maverick xinetd[11740]: removing time
Mar 14 21:57:06 maverick xinetd[11740]: bind failed (Address already in use (errno = 98)). service = x11vnc
Mar 14 21:57:06 maverick xinetd[11740]: Service x11vnc failed to start and is deactivated.
Mar 14 21:57:06 maverick xinetd[11740]: xinetd Version 2.3.14 started with libwrap loadavg options compiled in.
Mar 14 21:57:06 maverick xinetd[11740]: Started working: 0 available services

[jpkotta]

This is what I use to connect to an already running server (on display :0):

#!/bin/bash

usage="$0 [user@]remote_host"

if [[ x$1 == x"" ]] ; then
    echo $usage
    exit 1
fi

ssh $1 'x11vnc -localhost -display :0 -scale 4/5 -bg' 
vncviewer -via $1 -encodings 'copyrect tight zrle hextile' localhost:0

All you need is X11Forwarding in ssh.

[krunge]

Mar 14 21:57:06 maverick xinetd[11740]: bind failed (Address already in use (errno = 9 ). service = x11vnc

It looks like something else is already listening on port 5900.

Check 'netstat -ant | grep 5900' output and (perhaps as root) 'lsof -P | grep 5900'

[Al_maverick]

It looks like something else is already listening on port 5900.

Check 'netstat -ant | grep 5900' output and (perhaps as root) 'lsof -P | grep 5900'

That was it. I dunno why, krfb was still running. I killed it, then inmediately afterwards I restarted xinetd. Now it worked. Thanks a lot!

[FlashUK]

Very useful thread. Been following the steps to get x11vnc working on edgy 6.10 ubuntu.
Managed to get it to work on the end on port 5900 but I'd like to point out a mistake on the karlrunge.com that had me scrathing my head for ages:

x11vnc -display :0 -auth /var/gdm/:0.Xauth

Please note that ubuntu's gdm is located at /var/lib/gdm/:0.Xauth. I missed out the word lib when I was writing my xinetd file.
But now it even works on bootup! Thanks very much for sharing this with us

Btw, edgy currently uses 0.8.2 of x11vnc.