please advice:I add next iptables rules:iptables -I OUTPUT 2 -p udp --dport 53 -j ACCEPTiptables -I OUTPUT 2 -p udp --dport 1700:1750 -j ACCEPTiptables -I OUTPUT 3 -p udp -m udp --dport 1812 -j ACCEPTiptables -I OUTPUT 5 -p udp -m udp --dport 1813 -j ACCEPTiptables -I OUTPUT 5 -p udp -m udp --dport 5950:6050 -j ACCEPTiptables -I OUTPUT 5 -p udp -m udp --dport 499:510 -j ACCEPTiptables -I OUTPUT 5 -p udp -m udp --dport 4490:4550 -j ACCEPTiptables -I OUTPUT 20 -p udp -j DROPBut, after apply: ipsec, l2tp and openvp udp port 6000 stops workingAdvice, what is wrong?Here is my udp services:udp 0 0 0.0.0.0:500 0.0.0.0:* 3115/charonudp 0 0 0.0.0.0:1701 0.0.0.0:* 2885/xl2tpdudp 0 0 162.243.256.150:6000 0.0.0.0:* 2818/openvpnudp 0 0 0.0.0.0:4500 0.0.0.0:* 3115/charonudp6 0 0 :::500 :::* 3115/charon 
iptables advice with upd ports blocking in debian linux
debian;iptables