rsh from other linux machines on the network to my cygwin machine

rsh from other linux machines on the network to my cygwin machine

[Srikanth Katkam]

Hello,
I have installed Cygwin on my windows machine and able to successfully use it from many days!

However I have a question in my mind about the network access.

I can do rsh/ssh onto other linux machines in the network and use all the resources on those machines but I cannot do the reverse, i.e., rsh on to my windows machine (i.e., Cygwin X server), why the other machines not able to see my cygwin/windows machine?

This is why I am not able to run any DISPLAY required applications on the other linux machines (which rsh'ed on to from my cygwin/windows machine).  The main reason is when I set the DISPLAY environment variable on the linux machines as my_windows_machine:0.0 it says cannot open DISPLAY

Can you please let me know, how I can get this working!

Thanks in advance!

Regards,
Srikanth K


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Re: rsh from other linux machines on the network to my cygwin machine

[Charles Wilson]

On 2/16/2011 6:17 PM, Srikanth Katkam wrote:
> I can do rsh/ssh onto other linux machines in the network and use
> all the resources on those machines but I cannot do the reverse, i.e., rsh
> on to my windows machine (i.e., Cygwin X server), why the other machines
> not able to see my cygwin/windows machine?
>
> This is why I am not able to run any DISPLAY required applications
> on the other linux machines (which rsh'ed on to from my cygwin/windows
> machine). The main reason is when I set the DISPLAY environment variable
> on the linux machines as my_windows_machine:0.0 it says cannot
> open DISPLAY

Your title does not appear to match the question you are asking.

If you are logged on to a linux box, and want to rsh over to your cygwin
box ... then you need to set up the rshd server on your cygwin box.  See
/usr/share/doc/Cygwin/rsh-server.README

If you are logged on to a linux box, and want to ssh over to your cygwin
box ... then you need to setup up the sshd server on your cygwin box.
See /usr/share/doc/Cygwin/openssh.README (but basically, run
/usr/bin/ssh-host-config and answer the questions).

That answers what your TITLE appears to ask.  However, the TEXT of your
question appears to ask a completely different question:

You are ssh'ing from cygwin to linux, and want to run an X application
on the linux machine, and have the display show up on your local cygwin
box -- but it's not working.

OK, FIRST you have to install and configure the cygwin Xserver, and have
it running.

SECOND, you need to be able to display X apps LOCALLY on cygwin box.
e.g. launch an xterm on the cygwin box.

THEN, from /that xterm/ on your cygwin box, do this:
	ssh -Y remote_linux_host

FINALLY, once logged on to the linux host, launch an X app.  It should work.

Read about the -Y (and -X) options...

--
Chuck

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Re: rsh from other linux machines on the network to my cygwin machine

[Jon TURNEY]

On 16/02/2011 23:41, Charles Wilson wrote:
> On 2/16/2011 6:17 PM, Srikanth Katkam wrote:
>> I can do rsh/ssh onto other linux machines in the network and use
>> all the resources on those machines but I cannot do the reverse, i.e., rsh
>> on to my windows machine (i.e., Cygwin X server), why the other machines
>> not able to see my cygwin/windows machine?
>>
>> This is why I am not able to run any DISPLAY required applications
>> on the other linux machines (which rsh'ed on to from my cygwin/windows
>> machine). The main reason is when I set the DISPLAY environment variable
>> on the linux machines as my_windows_machine:0.0 it says cannot
>> open DISPLAY

This is probably because you need to inform the X server to allow connections
from that other host, typically by running 'xhost my_linux_machine' on the
cygwin machine.

The instructions at [1] are only intended to describe how to make remote X
clients display on a Cygwin X server, but should be sufficiently general that
they give a good idea how to make it work in the opposite direction also.
I'll amend them so they mention that rsh behaves in the same way as telnet.

Security advice: The use of telnet and rsh for remote logins should be
discontinued under all normal circumstances

Additional security advice: If you have need of security advice, don't get it
from some random person on the internet.

> Your title does not appear to match the question you are asking.

Yes, I'm afraid your email is rather confusing, it seems to switch between
asking about cygwin->linux and linux->cygwin connections.

> If you are logged on to a linux box, and want to rsh over to your cygwin
> box ... then you need to set up the rshd server on your cygwin box.  See
> /usr/share/doc/Cygwin/rsh-server.README
> 
> If you are logged on to a linux box, and want to ssh over to your cygwin
> box ... then you need to setup up the sshd server on your cygwin box.
> See /usr/share/doc/Cygwin/openssh.README (but basically, run
> /usr/bin/ssh-host-config and answer the questions).

Additionally, if you want to forward X connections over ssh, you need to:

- configure sshd to allow them by adding 'ForwardX11 yes' to /etc/sshd_config
(and restarting or SIGHUP sshd)
- install xauth

See [2] for more reasons why X11 forwarding over ssh might not be working.

> That answers what your TITLE appears to ask.  However, the TEXT of your
> question appears to ask a completely different question:
> 
> You are ssh'ing from cygwin to linux, and want to run an X application
> on the linux machine, and have the display show up on your local cygwin
> box -- but it's not working.
> 
> OK, FIRST you have to install and configure the cygwin Xserver, and have
> it running.
> 
> SECOND, you need to be able to display X apps LOCALLY on cygwin box.
> e.g. launch an xterm on the cygwin box.
> 
> THEN, from /that xterm/ on your cygwin box, do this:
> 	ssh -Y remote_linux_host
> 
> FINALLY, once logged on to the linux host, launch an X app.  It should work.
> 
> Read about the -Y (and -X) options...

[1] http://x.cygwin.com/docs/ug/using-remote-apps.html#using-remote-apps-telnet
[2] http://x.cygwin.com/docs/faq/cygwin-x-faq.html#q-ssh-no-x11forwarding

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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