You can do this with the standard command-line FTP client.

RTFM ftp(1) and look for the proxy command.

The basic idea is:

You start FTP by itself. (i.e., ftp, not ftp hostname.)

You connect to the "main" machine via

ftp> open primaryhost

You connect to the other machine via

ftp> proxy open otherhost

Once logged on to each host, you can do normal stuff - e.g., like

cd /some/path/on/primaryhost

proxy cd /some/path/on/otherhost

Once you're ready, do a proxy get filename (or proxy put filename, etc.)

Voila!

Oh, and you have to set Passive Mode (PASV) for this to work, obviously.

[ Reply to This | # ]

You connect to the other machine via 

ftp> proxy open otherhost

---
?>

[ Reply to This | # ]