possible to daisy chain ssh into single command?

lleb · 05-28-2014, 08:46 PM

I know this may sound a bit silly, but I was playing around with executing a command via ssh and starting trying to ssh from server A into server B and then into C all on a single command?

ex:

Code:

$ ssh userB@serverB 'ssh userC@serverC'

this presented me with the expect p/w prompt for server B, but failed to execute the ssh into server C. I also tried with -t, but that was definitely not what i am looking for.

im not even sure this is doable, so thanks in advance.

evo2 · 05-28-2014, 09:03 PM

Hi,

the ProxyCommand directive is good for this. Eg in your ~/.ssh/config

Code:

Host serverC
  User userC
  ProxyCommand ssh -qax serverB /usr/bin/nc %h %p

Host serverB
  User userB

Then from serverA as userA you can get to serverC as userC with the following command:

Code:

ssh serverC

HTH,

Evo2.

PS. If the ssh on serverA is new enough you don't need to use netcat. Instead the ProxyCommand line can be

Code:

ProxyCommand ssh -qax -W %h:%p serverB

Check the ssh man page for the -W option.

GaWdLy · 05-28-2014, 09:03 PM

It's doable by bash somewhat, but even moreso by Expect. I don't know of any way to just "daisy-chain" the commands without a script being used, though (I'm far from an expert, though).

lleb · 05-28-2014, 11:55 PM

Quote:

Originally Posted by evo2

Hi,

the ProxyCommand directive is good for this. Eg in your ~/.ssh/config

Code:

Host serverC
  User userC
  ProxyCommand ssh -qax serverB /usr/bin/nc %h %p

Host serverB
  User userB

Then from serverA as userA you can get to serverC as userC with the following command:

Code:

ssh serverC

HTH,

Evo2.

PS. If the ssh on serverA is new enough you don't need to use netcat. Instead the ProxyCommand line can be

Code:

ProxyCommand ssh -qax -W %h:%p serverB

Check the ssh man page for the -W option.

now that is some powerful stuff. many thanks. +1 mate.