Returns a log of the packets that have been sent and received.
Returns a string if NET_SSH2_LOGGING == NET_SSH2_LOG_COMPLEX, an array if NET_SSH2_LOGGING == NET_SSH2_LOG_SIMPLE and false if !defined('NET_SSH2_LOGGING')
Caching this the first time you connect to a server and checking the result on subsequent connections is recommended. Returns false if the server signature is not signed correctly with the public host key.