Different Versions of SSH

.ssh/

.ssh/

.ssh2/

identity

identity

id_dsa

id_dsa_1024_a

identification

authorized_keys

authorized_keys

authorization

known_hosts

known_hosts

host_keys/

This is to show two other types of setup you may encounter, besides the OpenSSH setup at MSRI. OpenSSH supports both version 1 and version 2 of the SSH protocol. SSH1 is the commercial implementation of SSH protocol version 1 and, of course, SSH2 is the commercial implementation of SSH protocol version 2. This is why SSH2 needs a different directory as a system can have both SSH1 and SSH2 installed on it.

As you can see, the only big changes come with SSH2. Instead of a single known_hosts file to hold the host keys of servers to which you connect, you get a directory with one file per host. The identification file is a list of private key files to try when using the public key method of authentication - you add a line for each new private key, like:

  IdKey  id_dsa_1024_a

The authorization file is similar. Instead of having an authorized_keys file with the contents of one authorized public key per line, you have:

  Key  id_dsa_1024_a.pub

where each line lists one file to check for a matching public key.