I installed APF Firewall in the server where I installed my nagios monitoring system.. APF is configured for all the open ports in the same server, including of course port 21 (ftp). But the problem is that if firewall is up, Nagios shows a few warnings about FTP problems with lot of servers... false warnings. If the firewall is down, no warning is displayed..
I'm using RHES 4 + Nagios 2.0 + APF 0.96
Can anyone guide me to solve this problem ?