Get SSH server software name
SSH components allow you to access the name of the software that runs on the server side (or its identifier, to be exact - with examples as Mikrotik_v2.9, OpenSSH_4.3 and mod_sftp/0.9.8). To get the name, check the ServerSoftwareName property. This returns the identifier put by the remote software to SSH 'hello' method.
string servername = client.ServerSoftwareName;
As software name is transmitted at the very beginning of the communication, you can check it on almost all stages of the connection - e.g. after Open() method completes, or from OnKeyValidate, OnAuthenticationStart or OnError event handlers.