SSH Connection Problems
When I attempted to use the command 'ssh-agent' then the command 'ssh-add' to enter my rsa passphrase and allow me to login to a host without typing my passphrase in all the time. The error I got after entering 'ssh-add' was 'Could not open a connection to your authentication agent'.
The solution was to enter the command 'exec ssh-agent bash' the command 'ssh-add' then the passphrase. It worked after this not sure why, it used to work before, could have been an upgrade in Ubuntu 9.10.