Comments on: SSH Pop Quiz

By: anon

anon — Sun, 08 Mar 2009 18:32:17 +0000

A bit off topic but if you need to send a file from the server you are on to another one – but need to go through a middle-man and do not want to setup agent:

tar -cf – * | ssh proxyuser@proxyhost “cat – | ssh
destinationuser@destinationhost ‘cat – > file.tar’”

That will tar up a directory & send it over ssh at the same time and name it at your destination as file.tar

By: jimcooncat

jimcooncat — Sun, 08 Mar 2009 16:30:53 +0000

If you only need shell access, and you trust the machine1, then you could just leave a screen session on machine1 that is ssh’d into machine 2.

Have your home machine ssh into machine1 and have it reconnect to the screen session.

This way is fast, and keeps a long-running terminal with history available. Also good if you have different users or authentication setup for each connection.You lose nice features like scp though.

By: Mike Vincent

Mike Vincent — Sat, 07 Mar 2009 16:11:54 +0000

I’ve used both..
ProxyCommand ssh proxy.example.com ‘exec 3/dev/tcp/%h/22;(cat &3′

And..
ProxyCommand ssh proxy.example.com nc -w 1 %h %p

Both work great, you can even scp seamlessly through the proxy.

Only problem I find is I end up with a lot of stale sessions on the proxy host.

By: anonymous_from_tatooine

anonymous_from_tatooine — Sat, 07 Mar 2009 14:13:28 +0000

why not just

ssh -t machine1 ‘ssh -t machine2′

By: Marius Gedminas

Marius Gedminas — Sat, 07 Mar 2009 12:54:33 +0000

Here’s the obligatory example using netcat:

Host machine1 machine2 machine3
ProxyCommand ssh -q -a -x firewall nc -w 1 %h %p

By: foo

foo — Sat, 07 Mar 2009 09:26:10 +0000

By the way, you can use `nc` (netcat) instead of `tcpconnect`, it’s the same (in my case nc wasn’t installed on the proxy).

By: martijn

martijn — Sat, 07 Mar 2009 08:30:16 +0000

‘ForwardAgent yes’ does exactly what you’re looking for.

By: hans

hans — Sat, 07 Mar 2009 05:44:42 +0000

An alias (or shell function or shell script) seems like the right thing to me too. But that *.proxied trick is pretty slick.

By: Christer Edwards

Christer Edwards — Sat, 07 Mar 2009 03:20:52 +0000

@mike – I did think about using an alias, and that would be a very simple solution. The drawback to that in my mind is that the configuration for my ssh connections is then spread between two files and two formats. When I do backups and restores of my machine it’d be one more file to add to the list. I’d prefer to just be able to backup my .ssh/ directory and have my keys, known hosts and settings all there.

By: mike hancock

mike hancock — Sat, 07 Mar 2009 03:16:39 +0000

this is not a correct solution, but what about using alias to map the command “ssh machine1″ to actually run what you want. sounds like this is exactly what alias is meant to do?

note
sorry if i am off base here; just an idea