Not sure whether this is of any help in your particular situation, but you can bind to the same port on a single interface by giving said interface several IP addresses. This could be either several external IP addresses or several internal addresses in the 127.0.0.0/24 range. So you could have your web server bind to port 80 on 127.0.0.1 and have your RPC service bind to port 80 on 127.0.0.2 (ditto for two external addresses). If your intention is to get around some firewall restrictions by using port 80 for telnet then this would work (albeit it may be a very bad idea).