CentOS 6.3 VNCSERVER setup

From: http://wiki.centos.org/HowTos/VNC-Server

1. Installing the required packages

The server package is called 'vnc-server'. Run the command: rpm -q vnc-server

The result will be either package vnc-server is not installed or something like vnc-server-4.0-11.el4.

If the server is not installed, install it with the command: yum install vnc-server

The client program is 'vnc'. You can use the command: yum install vnc to install the client if: rpm -q vnc shows that it is not already installed.

Make sure to install a window manager in order to get a full-featured GUI desktop. You can use the command yum groupinstall "GNOME Desktop Environment" to install the Gnome Desktop and requirements, for example. Other popular desktop environments are "KDE" and "XFCE-4.4". XFCE is more light-weight than Gnome or KDE and available from the "extras" repository.

If you are a minimalist, or simply testing, however, it is sufficient to have yum install a simple XTERM client: yum install xterm

If you are running CentOS 6, the command is yum groupinstall Desktop

If you are running CentOS 5, yum groupinstall "GNOME Desktop Environment" may complain about a missing libgaim.so.0. This is a known bug. Please see CentOS-5 FAQ for details.

If you are running CentOS 6, the server is: tigervnc-server not: vnc-server

2. Configuring un-encrypted VNC

We will be setting up VNC for 3 users. These will be 'larry', 'moe', and 'curly'

You will perform the following steps to configure your VNC server:

1. Create the VNC users accounts.
2. Edit the server configuration.
3. Set your users' VNC passwords.
4. Confirm that the vncserver will start and stop cleanly.
5. Create and customize xstartup scripts.
6. Amend the iptables.
7. Start the VNC service.
8. Test each VNC user.
9. Additional optional enhancements

2.1. Create the VNC user accounts

As root:

$ su -
# useradd larry
# useradd moe
# useradd curly
# passwd larry
# passwd moe
# passwd curly

2.2. Edit the server configuration

Edit /etc/sysconfig/vncservers, and add the following to the end of the file.

VNCSERVERS="1:larry 2:moe 3:curly"
VNCSERVERARGS[1]="-geometry 640x480"
VNCSERVERARGS[2]="-geometry 640x480"
VNCSERVERARGS[3]="-geometry 800x600"

Larry will have a 640 by 480 screen, as will Moe. Curly will have an 800 by 600 screen.

Note: This step is NOT out of sequence, but is placed here so that the next following step will fall adjacent to the step in which failure to perform it, will permit immediate fault diagnosis.

2.3. Set your users' VNC passwords

Switch user into the account for each user, and as noted below, run: vncpasswd This will create the ~/.vnc directory for that userid:

[~]# su - larry
[~]$ vncpasswd
[~]$ cd .vnc
[.vnc]$ ls
passwd
[.vnc]$ exit
[~]#

2.4. Confirm that the vncserver will start and stop cleanly

We will create the xstartup scripts by starting and stopping the vncserver as root. We also enable the vncserver service to be automatically started.

# /sbin/service   vncserver start
# /sbin/service   vncserver stop
# /sbin/chkconfig vncserver on

Note: if you omitted the preceding step of logging in as each configured user, and creating their ~/.vnc/ subdirectory, this test will fail.

2.5. Create xstartup scripts ( You may omit this step for CentOS 6 )

Login to each user and edit the xstartup script. To use Larry as an example, first login as larry

[~]$ cd .vnc
[.vnc] ls
mymachine.localnet:1.log  passwd  xstartup

Edit ~/.vnc/xstartup for each user. The original should appear as follows:

#!/bin/sh
# Uncomment the following two lines for normal desktop:
# unset SESSION_MANAGER
# exec /etc/X11/xinit/xinitrc
[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
twm &

Add the line indicated below to assure that an xterm is always present, and uncomment the two lines as directed if you wish to run the user's normal desktop window manager in the VNC. Note that in the likely reduced resolution and color depth of a VNC window the full desktop will be rather cramped and a look bit odd. If you do not uncomment the two lines you will get a gray speckled background to the VNC window.

#!/bin/sh
# Add the following line to ensure you always have an xterm available.
( while true ; do xterm ; done ) &
# Uncomment the following two lines for normal desktop:
unset SESSION_MANAGER
exec /etc/X11/xinit/xinitrc
[ -x /etc/vnc/xstartup ] && exec /etc/vnc/xstartup
[ -r $HOME/.Xresources ] && xrdb $HOME/.Xresources
xsetroot -solid grey
vncconfig -iconic &
xterm -geometry 80x24+10+10 -ls -title "$VNCDESKTOP Desktop" &
twm &

2.6. Amend the iptables

The iptables rules in /etc/sysconfig/ need to be amended to open the VNC ports; as needed, if a local ipv6 setup is being used, those need to be amended as well:

[root@xen-221 sysconfig]# cat iptables
# Firewall configuration written by system-config-firewall
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -i eth1 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp -m multiport --dports 5901:5903,6001:6003 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT
[root@xen-221 sysconfig]#         

... and then restart the iptables:

# /sbin/service iptables restart

2.7. Start the VNC server

Start the vncserver as root.

# /sbin/service vncserver start