code: def authenticate_server(self, response):
          
  
          log.debug("authenticate_server(): Authenticate header: {0}".format(
              _negotiate_value(response)))
  
          host = urlparse(response.url).hostname
  
          try:
              # If this is set pass along the struct to Kerberos
              if self.cbt_struct:
                  result = kerberos.authGSSClientStep(self.context[host],
                                                      _negotiate_value(response),
                                                      channel_bindings=self.cbt_struct)
              else:
                  result = kerberos.authGSSClientStep(self.context[host],
                                                      _negotiate_value(response))
          except kerberos.GSSError:
              log.exception("authenticate_server(): authGSSClientStep() failed:")
              return False
  
          if result < 1:
              log.error("authenticate_server(): authGSSClientStep() failed: "
                        "{0}".format(result))
              return False
  
          log.debug("authenticate_server(): returning {0}".format(response))
          return True
docs: Uses GSSAPI to authenticate the server.
  
          Returns True on success, False on failure.