When I have iptables on, I can't connect to my server via FTP.
When I turn iptables off, I can.
It's something to do with the ports used for PASV (passive) connections, which I have defined in the FTP server conf as the range 50000-51000
I've already added this line to my iptables:
-A INPUT -m state --state NEW -m tcp -p tcp --sport 50000:51000 -j ACCEPT
That same syntax worked fine for opening port 80 for http, others for mysql, postmap, and dovecot for IMAP/POP etc.
The syntax & options for iptables is mysterious to me. I just picked up a manual which I'll read over the weekend, but meanwhile can someone tell me what I've done wrong?