%{+n}
###  set firewall <host:port>
   specifies your telnet proxy server if you're behind a firewall.
   leave this blank if you have a normal (direct) net connection.
   if set, this should contain the host and port of your socks v4
   proxy server.  it may start with a '!' if you're on a sun telnet
   passthru server (this barely works, if at all -- consider using
   socks).
see also: set reserved-port
