How do I set up ssh?

Here is what to do
~~~~~~~~~~~~~~~~~~

There are two versions (levels) of ssh (ssh1 and ssh2 on our machines) 
which are not normally compatible. On a given machine
 type  ssh -V to find out what is running (if any!) 

In what follows
$ lines are typed
> lines are system generated

e.g. to make sune.amtp.liv.ac.uk reachable from ukqcd2.ph.ed.ac.uk 
     and vice-versa.

on local machine (sune)
~~~~~~~~~~~~~~~~~~~~~~~
To generate private key (in 'identity') and public key (in 'identity.pub'):
$ mkdir .ssh
$ cd .ssh
$ ssh-keygen
>Initializing random number generator...
>Generating p:  ....++ (distance 100)
>Generating q:  ...................++ (distance 324)
>Computing the keys...
>Testing the keys...
>Key generation complete.
>Enter file in which to save the key
>(/home/damtp/users/aci/.ssh/identity): 
>Enter passphrase: $$$$$$$$$$$$$$$$$$$$$$$$$$$$$ 
>Enter the same passphrase again: $$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>Your identification has been saved in
>/home/damtp/users/aci/.ssh/identity.
>Your public key is:
>XXXX XX
>XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>aci@sunu
>Your public key has been saved in
>/home/damtp/users/aci/.ssh/identity.pub

The pass-phrase is just that... pick a phrase that is memorable to you
Put in a miss-spelling and/or replace a letter by a digit to enhance
security.
 
on remote machine (ukqcd2)
~~~~~~~~~~~~~~~~~~~~~~~~~~
Copy in required keys from local machine:
$ mkdir .ssh
$ cd .ssh
$ rcp sune.amtp.liv.ac.uk:.ssh/identity* .

To use:
~~~~~~~
$ ssh sune.amtp.liv.ac.uk -l aci
> 
If problems add a flag -v to see what is going on.


The first time you use ssh, it may ask about adding a new
acceptable host. Just say 'yes' and keep going.
Every time, it will ask for your password which is now
encrypted. You don't seem to need to use the passphrase
except when making changes.