This is used by ftp.  the man page on ftp mentions it but
does not describe the syntax.  I'm also not entirely clear
that is does what I want....

I want to be able to set a proxy ftp SERVER so I can ftp
things from behind a firewall, just like in Netscape and
lynx.  In those two programs the syntax is:

server-ip:port

ie, 10.0.0.10:1234

but can't get this to work on ftp.

This should be documented better in the man page, too.