in /etc/csf folder create an file "csfpre.sh"
add following inside:
iptables -A INPUT -i venet0 -j ACCEPT
iptables -A OUTPUT -o venet0 -j ACCEPT
iptables -A FORWARD -j ACCEPT -p all -s 0/0 -i venet0
iptables -A FORWARD -j ACCEPT -p all -s 0/0 -o venet0
/etc/csf/csfpre.sh is executed before all the other iptables statements when csf is started, by default the file is not created.
the file stays there after update complete csf.
so no worries, you have to add it every time again after csf update. (/etc/csf/csf -u)
regards Marco