Telnet handling under NAT

[drgrussell]

I have rewritten the NAT handler for telnet connections involving users who share a single IP. The new handler enters into telnet DO/DONT/WILL/WONT handshaking now with the client before asking for the IP number. This information is handled in a limited way, and where possible WILL is responded to by DO. Further handshaking is still done from the real telnetd server once the connection is made, and all handshaking is forwarded onto telnetd by my proxy.

This should support those telnet users who have a client which insists on initiating the telnet handshake before the server has sent its first handshake message.

It also puts all clients into DONT ECHO mode, which should improve screen handling a little.

Of course, this has probably broken users who were already quite happy, but only testing will tell. Let me know if you have any problems.

G.