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Hi guys, I'm pretty new to iptables so I got a couple of KVM machines and set up an ftp server. I used system-config-firewall-tui to set up the ftp port.
Bang.. works, the other machine can connect, job is good.
So I look at the changes to /etc/sysconfig/iptables and see that the config line is the same as the ssh one but for the ftp port of 21.
I take a copy of the file for reference
I take the rule out using system-config-firewall-tui and sure enough it's removed.
Then I put the rule in manually using vi (to make sure I did a yyp to copy the exact line then changed it to 21)
I restart iptables then check ising iptables -L and it reports that the ftp port is open.
However my other machine can't connect. I repeat this a few times and it appears that the rule works fine when done in system-config-firewall-tui but never when I've manually altered the file even though it reports as open. I made sure it was in the right place, directly below the ssh rule.
I also did a diff on the manually altered file and the one altered by the interface and they were identical.
Is there something I'm missing??
my iptables rule seems to work when set in the tui interface but not when manually editing the file. This is on Scientific Linux 6.5
- the iptables binary is the interface to the kernel part called Netfilter and no user interface shall interfere with using it that way,
- active FTP requires the control (TCP/21) and the data (TCP/20) port,
- the easiest way to debug iptables rules is to use "-j LOG" rules right before the actual rule,
- and I don't know about others but I'd rather see the actual rule set as in 'iptables-save' output.