ssh server

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hgm
Posts: 27788
Joined: Fri Mar 10, 2006 10:06 am
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Full name: H G Muller

ssh server

Post by hgm »

I installed freeSSHd as an ssh server on a windows machine, with the aim to run a remote engine there. Indeed I can run the engine from the command line, from another Windows machine using plink, but the problem is that apart from the normal engine output I get the commands I send it echoed back to me. A GUI (in particular Polyglot) does not like that at all, so I cannot play the engine automatically.

I also tried to connect from a Linux machine using genuine ssh. Then I also get the commands echoed to me, (I get to see every command twice, from the command line), but the engine doesn't react to them at all. I do see the welcome message of the engine, though, so I know that I am connected and that the engine is running. This is presumably a CR/LF problem. But it suggests the echo originates from the server, and not from the client.

Is it normal that an ssh server would echo everything you send it? Or is freeSSHd just a crappy implementation?
Daniel Shawul
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Location: Ethiopia

Re: ssh server

Post by Daniel Shawul »

If it is anything like telnet, you have to negotiate to turn off echoing (WON'T ECHO or something like that). I think it is on by default http://support.microsoft.com/kb/231866
But I don't know much about protocols..
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mhull
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Full name: Matthew Hull

Re: ssh server

Post by mhull »

hgm wrote:I installed freeSSHd as an ssh server on a windows machine, with the aim to run a remote engine there. Indeed I can run the engine from the command line, from another Windows machine using plink, but the problem is that apart from the normal engine output I get the commands I send it echoed back to me. A GUI (in particular Polyglot) does not like that at all, so I cannot play the engine automatically.

I also tried to connect from a Linux machine using genuine ssh. Then I also get the commands echoed to me, (I get to see every command twice, from the command line), but the engine doesn't react to them at all. I do see the welcome message of the engine, though, so I know that I am connected and that the engine is running. This is presumably a CR/LF problem. But it suggests the echo originates from the server, and not from the client.

Is it normal that an ssh server would echo everything you send it? Or is freeSSHd just a crappy implementation?
If you are using PuTTY on the client side, it's supposed to try and figure out whether local echo is appropriate or not. If it's not doing it right, you can force it to echo or not upon invocation (I think).

http://the.earth.li/~sgtatham/putty/0.6 ... -localecho
Matthew Hull
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sje
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Joined: Mon Mar 13, 2006 7:43 pm

Re: ssh server

Post by sje »

The Linux openssh implementation appears in all respects to be functionally equivalent to the same system in OpenBSD. I have run all possible client/server combinations and they all work and they work in the same way.

By default, there is no local echo. I don't know why one would want this anyway.
bob
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Joined: Mon Feb 27, 2006 7:30 pm
Location: Birmingham, AL

Re: ssh server

Post by bob »

hgm wrote:I installed freeSSHd as an ssh server on a windows machine, with the aim to run a remote engine there. Indeed I can run the engine from the command line, from another Windows machine using plink, but the problem is that apart from the normal engine output I get the commands I send it echoed back to me. A GUI (in particular Polyglot) does not like that at all, so I cannot play the engine automatically.

I also tried to connect from a Linux machine using genuine ssh. Then I also get the commands echoed to me, (I get to see every command twice, from the command line), but the engine doesn't react to them at all. I do see the welcome message of the engine, though, so I know that I am connected and that the engine is running. This is presumably a CR/LF problem. But it suggests the echo originates from the server, and not from the client.

Is it normal that an ssh server would echo everything you send it? Or is freeSSHd just a crappy implementation?
I use ssh all the time and do not see this ever. I see characters echoed as I type them, of course. I almost suspect this is an artifact of windows, but I am not a windows expert.
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Don
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Joined: Tue Apr 29, 2008 4:27 pm

Re: ssh server

Post by Don »

hgm wrote:I installed freeSSHd as an ssh server on a windows machine, with the aim to run a remote engine there. Indeed I can run the engine from the command line, from another Windows machine using plink, but the problem is that apart from the normal engine output I get the commands I send it echoed back to me. A GUI (in particular Polyglot) does not like that at all, so I cannot play the engine automatically.

I also tried to connect from a Linux machine using genuine ssh. Then I also get the commands echoed to me, (I get to see every command twice, from the command line), but the engine doesn't react to them at all. I do see the welcome message of the engine, though, so I know that I am connected and that the engine is running. This is presumably a CR/LF problem. But it suggests the echo originates from the server, and not from the client.

Is it normal that an ssh server would echo everything you send it? Or is freeSSHd just a crappy implementation?
At Leiden and many other times we use xboard locally and run the chess program remotely by just setting up the program like this:

-fcp "ssh some_linux_machine.com komodo"

and it works flawlessly (as long as you set the keys up properly of course.) There should be no echo, no problem.

It almost sounds like the remote shell thinks it's a terminal or something - maybe there is a configuration option to turn that off?

Can you connect TO a program on a linux machine and make this work?