-be zero to allow the server to automatically chose an interface. A server
-that is not willing to open a client-specified unit should refuse the
-request with a SSH_MSG_CHANNEL_OPEN_FAILURE error. On successful open,
-the server should reply with SSH_MSG_CHANNEL_OPEN_SUCCESS.
+be 0x7fffffff to allow the server to automatically chose an interface. A
+server that is not willing to open a client-specified unit should refuse
+the request with a SSH_MSG_CHANNEL_OPEN_FAILURE error. On successful
+open, the server should reply with SSH_MSG_CHANNEL_OPEN_SUCCESS.