The extssh connection method uses a built-in SSH client. The ext connection method allows you to specify an external SSH client to use. For extssh to work with Eclipse 2.1.x and before, the server must be running an SSH server with SSH1 protocol compatibility. If extssh does not work, it is possible that the server is running only the SSH2 protocol. If this is the case, you must configure the ext connection method with an external SSH client. In Eclipse 3.0 and beyond, extssh does support SSH2.