TElIdSSHConnection is a descendant of TIdTCPConnection.
SSH protocol supports establishing of a number of logical connections which are tunneled over it. Each tunnel object is a representation of logical connections of a specific type (such as remote tcp port forwarding). TElIdSSHConnection class deals with a single logical connection. I.E., one TElRemotePortForwardSSHTunnel tunnel object will create a logical connection for each tcp connection established on remote side.