def start_server(self, event=None, server=None):
if server is None:<EOL><INDENT>server = ServerInterface()<EOL><DEDENT>self.server_mode = True<EOL>self.server_object = server<EOL>self.active = True<EOL>if event is not None:<EOL><INDENT>self.completion_event = event<EOL>self.start()<EOL>return<EOL><DEDENT>self.completion_event = event = threading.Event()<EOL>self.start()<EOL>while True:<EOL><INDENT>event.wait(<NUM_LIT:0.1>)<EOL>if not self.active:<EOL><INDENT>e = self.get_exception()<EOL>if e is not None:<EOL><INDENT>raise e<EOL><DEDENT>raise SSHException('<STR_LIT>')<EOL><DEDENT>if event.isSet():<EOL><INDENT>break<EOL><DEDENT><DEDENT>
Negotiate a new SSH2 session as a server.  This is the first step after
creating a new L{Transport} and setting up your server host key(s).  A
separate thread is created for protocol negotiation.

If an event is passed in, this method returns immediately.  When
negotiation is done (successful or not), the given C{Event} will
be triggered.  On failure, L{is_active} will return C{False}.

(Since 1.4) If C{event} is C{None}, this method will not return until
negotation is done.  On success, the method returns normally.
Otherwise an SSHException is raised.

After a successful negotiation, the client will need to authenticate.
Override the methods
L{get_allowed_auths <ServerInterface.get_allowed_auths>},
L{check_auth_none <ServerInterface.check_auth_none>},
L{check_auth_password <ServerInterface.check_auth_password>}, and
L{check_auth_publickey <ServerInterface.check_auth_publickey>} in the
given C{server} object to control the authentication process.

After a successful authentication, the client should request to open
a channel.  Override
L{check_channel_request <ServerInterface.check_channel_request>} in the
given C{server} object to allow channels to be opened.

@note: After calling this method (or L{start_client} or L{connect}),
    you should no longer directly read from or write to the original
    socket object.

@param event: an event to trigger when negotiation is complete.
@type event: threading.Event
@param server: an object used to perform authentication and create
    L{Channel}s.
@type server: L{server.ServerInterface}

@raise SSHException: if negotiation fails (and no C{event} was passed
    in)