SSH

To set up passwordless SSH, there are three main things to do:

   * generate a pair of public/private keys on your local computer
   * copy the public key from the source computer to the target computer's authorized_keys file
   * check the permissions. 

You can repeat that transitively for "A->B->C". You can use the initial pair of keys everywhere.

See here for details:

http://www.stearns.org/doc/ssh-techniques.current.html

Making life with SSH on HCL easier

Here is a very convenient way to set up the access to any machine directly instead of doing a cascade of SSH calls :

Host csserver
  User kdichev
  Hostname csserver.ucd.ie
Host heterogeneous
  User kiril
  Hostname heterogeneous.ucd.ie
  ProxyCommand ssh -qax csserver nc %h %p
Host hcl01
  Hostname hcl01.ucd.ie
  ProxyCommand ssh -qax heterogeneous nc %h %p

Now, you can do:

ssh hcl01

and you get logged to the node immediately.