iptables

INPUT

Workign on this

OUTPUT

DNS Blocking

(May not working)

iptables -I OUTPUT -p udp --dport 53 -m string --string facebook --algo bm -j DROP

Routing

POST Routing

iptables -A POSTROUTING -s 192.168.0.0/16 -o eth0 -j MASQUERADE

Masquerade

iptables -t nat -A POSTROUTING -j MASQUERADE

PRE Routing

iptables -A PREROUTING -i eth0 -p tcp -m tcp -s 100.100.100.5 -d 192.168.1.30 --dport 443 -j DNAT --to-destination 192.168.1.100:443

Port Forwarding

Forward traffic on port 2222 to IP 10.1.1.2 on port 22

iptables -t nat -A PREROUTING -p tcp --dport 2222 -j DNAT --to-destination 10.1.1.2:22

ICMP

Disable PING and MTR / traceroute request

For iptables rules

iptables -A OUTPUT -p icmp  --icmp-type 0 -j DROP
iptables -A OUTPUT -p icmp  --icmp-type 8 -j DROP
iptables -A OUTPUT -p icmp  --icmp-type 11 -j DROP
iptables -A OUTPUT -p icmp  --icmp-type 30 -j DROP

To disable traceroute

iptables -A INPUT -p icmp -m ttl --ttl-eq 1 -j DROP
iptables -A INPUT -p udp -m ttl --ttl-eq 1 -j DROP
iptables -A INPUT -p tcp -m ttl --ttl-eq 1 -j DROP

***Reference: ***

• System Security Configuration - PhoenixWiki