Let a console work through a forwarded ipmi port

A bmc behind a forward answers Activate Payload with the port it listens on
itself, and the advertised-port check refused that, so a console failed where
command traffic worked. The advertised port is never sent to, so the check now
applies only on the default port. A bmc on another port advertising a third one
is no longer refused outright, which nothing here could have served anyway.

confluent_server/aiohmi/ipmi/console.py

@@ -148,7 +148,11 @@ class Console(object):
         # some BMCs disagree on the endianness, so do both
         valid_ports = (self.port, struct.unpack(
             '<H', struct.pack('>H', self.port))[0])
-        if (data[8] + (data[9] << 8)) not in valid_ports:
+        solport = data[8] + (data[9] << 8)
+        # A bmc behind a port forward answers with the port it listens on
+        # rather than the one it was reached through; payloads ride the
+        # session, never the advertised port.
+        if solport not in valid_ports and self.port == 623:
             # TODO(jbjohnso): support atypical SOL port number
             raise NotImplementedError("Non-standard SOL Port Number")
         # ignore data[10:11] for now, the vlan detail, shouldn't matter to this