just kwick n dirty:
if you want to get rid of that bothering passphrase while connecting via ssh to a host, just append your ~/.ssh/id_rsa.pub on your local machine to the file ~/.ssh/authorized_keys on the target host.
scp ~/.ssh/id_rsa.pub <user>@<host>:/<home>/<user>/.ssh
then log into the target machine, and enter
cat ~/.ssh/id_rsa.pub >> ~/ssh/authorized_keys'''
even faster: there if you start the program ssh-agent it will provide some scripts that do things like this for you:
ssh-copy-id -i ~/.ssh/id_rsa.pub <user>@<host>
if you don't find a key under ~/.ssh/ have a look at Ssh-dsa-key_generation
if you want to execute special commands on the remote machine automatically without logging in, try :ssh_authorized_keysfile see also: ssh