Hp - linux X-Application

[Nigel Wade]

Padiyath Sreekumaran wrote:
>   Hello,
>   I have the following problem. I want to use a SW which is installed on
> a HP.
>   My desktop is a RedHat installed linux machine. Iam logging with
> telnet 
>   (ssh is not installed on HP!)on HP. I did the following on my desktop.
>   Executed "xhost + " before logging to HP. Logged with telnet on HP and
> executed
>   the command setenv DISPLAY linuxxx:0. When I run "xclock" I get the
> following
>   error:
>   "Error: Can't open display: linuxxx:0"
> 
>   How can I overcome this error. I want to use an X-Application on HP.
>   I would like to have your suggestion as early as possible. I cannot
>   do anything HP since I donot have root privilege on that machine.
> 

There are two issues here, the X server itself and any firewall between 
the HP and the PC, including on the PC.

The X server by default does not listen for network connections, it only 
listens on a UNIX domain socket for connections from the local host. To 
enable network connections you need to modify /etc/X11/gdm/gdm.conf 
(assuming you are using gdm) and change the (probably commented out) 
line "DisallowTCP=true" to "DisallowTCP=false" and uncomment it. Then 
restart X.

After doing the above X will be listening on port 6000 (for DISPLAY :0). 
However, you probably still can't connect if a firewall is enabled on 
the RedHat PC. You will at the very least need to open port 6000 to 
allow your HP computer to connect to the X server. See 
<https://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/security-guide/ch-fw.html> 
for basic details on configuring iptables. If you are not connected to 
the Internet, or you are behind a router with a decent firewall you 
might just disable the firewall on the PC. If there is any other 
firewall between the HP and the PC then you will also need to configure 
that to allow port 6000 traffic incoming from the HP to the PC.

If you have the default firewall configuration on the PC then you can 
temporarily disable it with "service iptables stop". This should allow 
you to check the connection between the HP and the PC, but it should not 
be a long term solution. Re-enable the firewall with "service iptables 
start".

>   Thanks in advance,
>    Kumar
>   P.S. Please send a copy of the E-mail in my personal E-mail address
>        if possible. Thanks.

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-- 
Nigel Wade, System Administrator, Space Plasma Physics Group,
             University of Leicester, Leicester, LE1 7RH, UK
E-mail :    nmw at ion.le.ac.uk
Phone :     +44 (0)116 2523548, Fax : +44 (0)116 2523555