vnc-server installed and running but not visible over the network - centos

Question

Unable to connect on LAN using VNCViewer to a TigerVNC-Server on Centos
My Centos 6 installation of Vino or more accurately tigervnc-server is set up and starts successfully as defined by the procedure here:
http://wiki.centos.org/HowTos/VNC-Server
I am however unable to connect to the server using the vnc-client on a W7 machine or using a java enabled browser.
I have configured a user, namely '1:mark'
After running "ss -l" to determine the port (thanks to arcyqwerty for the netstat suggestion), I determined the correct port is 5901 or 5902.
ss -l output
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 50 *:mysql *:*
LISTEN 0 5 :::vnc-server :::*
LISTEN 0 5 *:5901 *:*
LISTEN 0 128 :::41485 :::*
LISTEN 0 5 :::5902 :::*
Below is the output of my /home/mark/.vnc/log after service start
Thu Dec 5 12:09:58 2013
vncext: VNC extension running!
vncext: Listening for VNC connections on all interface(s), port 5901
vncext: created VNC server for screen 0
GNOME_KEYRING_SOCKET=/tmp/keyring-icjZAi/socket
SSH_AUTH_SOCK=/tmp/keyring-icjZAi/socket.ssh
GNOME_KEYRING_PID=7644
Failed to play sound: File or data not found
An instance of nm-applet is already running.
** Message: adding killswitch idx 2 state KILLSWITCH_STATE_SOFT_BLOCKED
** Message: killswitch 2 is KILLSWITCH_STATE_SOFT_BLOCKED
** Message: killswitches state KILLSWITCH_STATE_SOFT_BLOCKED
05/12/2013 12:10:02 PM Autoprobing TCP port in (all) network interface
05/12/2013 12:10:02 PM Listening IPv{4,6}://*:5900
05/12/2013 12:10:02 PM Listening IPv4://0.0.0.0:5900
05/12/2013 12:10:02 PM Problems in NewSocketListenTCP(), sock=-1
05/12/2013 12:10:02 PM Listening IPv{4,6}://*:5901
05/12/2013 12:10:02 PM Listening IPv4://0.0.0.0:5901
05/12/2013 12:10:02 PM Problems in NewSocketListenTCP(), sock=-1
05/12/2013 12:10:02 PM Listening IPv{4,6}://*:5902
05/12/2013 12:10:02 PM Autoprobing selected port 5902
05/12/2013 12:10:02 PM Advertising authentication type: 'VNC Authentication' (2)
05/12/2013 12:10:02 PM Advertising security type: 'VNC Authentication' (2)
** Message: killswitch 2 is KILLSWITCH_STATE_SOFT_BLOCKED
** Message: killswitches state KILLSWITCH_STATE_SOFT_BLOCKED
(polkit-gnome-authentication-agent-1:7711): GLib-GObject-WARNING **: cannot register
existing type `_PolkitError'
(polkit-gnome-authentication-agent-1:7711): GLib-CRITICAL **: g_once_init_leave: assertion `initialization_value != 0' failed
Initializing nautilus-gdu extension
Initializing nautilus-open-terminal extension
(null): Warning no default label for /home/mark/.gvfs`
My /etc/sysconfig/vncservers contains
VNCSERVERS="1:mark"
VNCSERVERARGS[1]="-geometry 800x600"
However from the netstat it appears that ports 5900, 5901 and 5902 are involved.
Here are the results of my tests:
browsed on the host using 'localhost:5900' Result: RFB 003.007
browsed on the host using 'localhost:5901' Result: RFB 003.008. (note: user:mark)
browsed on the host using 'localhost:5902' Result: RFB 003.007
VNC'd on the host using 'localhost:5901' Result: worked.
Note: From http://www.realvnc.com/docs/rfbproto.pdf RFB represents the Remote Frame Buffer required protocol version numbers.
I tried 1,2,3 and 4 from above substituting localhost:port for the 'hosts ip':port on a network client machine and all timed-out.
The following extra steps have been taken
Turned off the firewall
Temporarily disabled SeLinux
Successfully pinged host from client on LAN.
I am also successfully running a visible httpd service from the offending host
Any pointers would be appreciated.

Answer 1

Make sure that the server is actually runnning (try ps or ps aux).
If that works, then try netstat to make sure it's LISTEN on the right port