# X forwarding over telnet



## Graaf_van_Vlaanderen (Jan 17, 2010)

I enabled telnet on one server and I can login through telnet except I cannot start any graphical applications. I'm sure something is missing on the client (running KDE)? Can anybody point me to some info about what is missing.

X over ssh is working fine, but I guess for telnet this works different.

I'm testing telnet to have an idea whether it's (much) faster than ssh or not.


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## graudeejs (Jan 17, 2010)

It's much more insecure then ssh, in fact it's so insecure, i don't understand why it's still available for user


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## honk (Jan 17, 2010)

You can't forward X11 via telnet. There is no port forwarding feature in the telnet protocol. But X11 is already a client/server network protocol and you can use it the old way.

1. The Xserver must be listening on a tcp port (e.g. 6000) reachable from the remote host. Listening on localhost is not sufficient.

2. Connect to the remote host with telnet and set the environment variable DISPLAY to point back to your Xserver (example [CMD=""]setenv DISPLAY 192.168.1.1:0.0[/CMD]). See DISPLAY NAMES section in [CMD=""]man 7 x[/CMD].

3. Within the telnet session to the remote host, start a x-application, like xclock.

The difference to what you mean by "X forwarding over telnet" is that this procedure requires a second tcp connection in the way back to your x11 host. But you _really_ should use forwarding with ssh to avoid eavesdropping!

cheers,
honk


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## Graaf_van_Vlaanderen (Jan 17, 2010)

killasmurf86 said:
			
		

> It's much more insecure then ssh, in fact it's so insecure, i don't understand why it's still available for user



You would be surprised  how many people still use it. If you mention ssh and sftp to some people it's like you 're speaking another language. All the companies I've worked for used something like telnet or rlogin and they're still using it.

I just want to know how I need to set it up and its performance.


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## Graaf_van_Vlaanderen (Jan 17, 2010)

honk said:
			
		

> You can't forward X11 via telnet. There is no port forwarding feature in the telnet protocol. But X11 is already a client/server network protocol and you can use it the old way.
> 
> 1. The Xserver must be listening on a tcp port (e.g. 6000) reachable from the remote host. Listening on localhost is not sufficient.
> 
> ...



Thanks, I remember the 'setenv DISPLAY', when I forgot this I started Cadence  sessions and nothing happened or it started on somebody else his machine. The last one was always funny.


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