All such requests use the
   following format.

      byte      SSH_MSG_GLOBAL_REQUEST
      string    request name in US-ASCII only
      boolean   want reply
      ....      request-specific data follows

   The value of 'request name' follows the DNS extensibility naming
   convention outlined in [SSH-ARCH].

   The recipient will respond to this message with
   SSH_MSG_REQUEST_SUCCESS or SSH_MSG_REQUEST_FAILURE if 'want reply' is
   TRUE.

      byte      SSH_MSG_REQUEST_SUCCESS
      ....     response specific data

   Usually, the 'response specific data' is non-existent.

   If the recipient does not recognize or support the request, it simply
   responds with SSH_MSG_REQUEST_FAILURE.

      byte      SSH_MSG_REQUEST_FAILURE

   In general, the reply messages do not include request type
   identifiers.  To make it possible for the originator of a request to
   identify to which request each reply refers, it is REQUIRED that
   replies to SSH_MSG_GLOBAL_REQUESTS MUST be sent in the same order as
   the corresponding request messages.  For channel requests, replies
   that relate to the same channel MUST also be replied to in the right
   order.  However, channel requests for distinct channels MAY be
   replied to out-of-order.