-The server starts by issuing a challenge line, with response code 231. This
-contains a random challenge encoded in hex.
+When a connection is made the server sends a \fB231\fR response before any
+command is received. This contains an algorithm name and a challenge encoded
+in hex.
+.PP
+Currently the algorithm name is omitted if it is \fBsha1\fR (but this will
+probably change in a future version). The other options are \fBsha256\fR,
+\fBsha384\fR and \fBsha512\fR. \fBSHA1\fR etc work as synonyms.