I am working on a Debian stable system and we want to add a rule to allow access for Nagios. Unfortunately, the rule is automatically getting deleted after some time. We are unable to find out what's going wrong. Any ideas? I have installed iptables-persistent package already.
iptables -I INPUT -p tcp --destination-port 5666 -j ACCEPT
Initially it shows with the following command, but then it suddenly disappears :
iptables -S | grep 5666