Topic: sme in server only behind a nat firewall

[brian MOore]

Greetings all  recently I changed my sme 5.1.2 server from a server and gateway to server only mode with a static ip behind a nat firewall.  all seems to be working fine as far as ports being forwarded correctly throught the firewall so my sme box is still accepting mail and my web site works and such.  however, there seems to be an issue with ftp access to my ibay.  I have ports 20 and 21 forwarded to the sme box for both udp and tcp packets, but I can't connect to an ibay with ftp.  the connection times out with socket connected waiting for welcome message.  from what little I can figure out about proftpd, when it recieves a connection, it responds with a response on a random port between 1024 and 65535.  obviously, opening this whole range is not an option.  would love to get this working correctly since my ibay contains a lot of data which I want to restrict to users who have the password. any tips would be appreciated.  thanks.  brian.
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[chris meredith]

Depending on what NAT firewall you have, some support FTP forwarding, rather than just generic port forwarding. This allows the NAT box to dynamically forward the correct port once the FTP session has been started.  You might also search for the difference between active and passive FTP for some more info.

[Mike]

http://www.castaglia.org/proftpd/doc/contrib/ProFTPD-mini-HOWTO-NAT.txt

Holp this help