When connecting Management Center to a ProxySG client (after the client has been reset to factory default settings), Management Center returns the error Incorrect Protocol.
After a factory reset, the ProxySG client may not generate an SSH Keyring.
To generate the SSH key for the ProxySG client:
> en
Enable Password:
#conf t
#(config) ssh-console
#(config ssh-console)create host-keypair
ok