def ssh_USERAUTH_REQUEST(self, packet):
        """
        The client has requested authentication.  Payload::
            string user
            string next service
            string method
            <authentication specific data>

        @type packet: L{bytes}
        """
        user, nextService, method, rest = getNS(packet, 3)
        if user != self.user or nextService != self.nextService:
            self.authenticatedWith = [] # clear auth state
        self.user = user
        self.nextService = nextService
        self.method = method
        d = self.tryAuth(method, user, rest)
        if not d:
            self._ebBadAuth(
                failure.Failure(error.ConchError('auth returned none')))
            return
        d.addCallback(self._cbFinishedAuth)
        d.addErrback(self._ebMaybeBadAuth)
        d.addErrback(self._ebBadAuth)
        return d

        The client has requested authentication.  Payload::
            string user
            string next service
            string method
            <authentication specific data>

        @type packet: L{bytes}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/userauth.py