Question : Icmp

How do I filter out the ICMP timestamp requests (ICMP type 13), the outgoing ICMP timestamp replies (ICMP type 14), the address mask request (ICMP type 17), and the address mask reply (ICMP type 18) ?

Answer : Icmp

iptables -A INPUT -p icmp --icmp-type 13
iptables -A INPUT -p icmp --icmp-type 14
iptables -A INPUT -p icmp --icmp-type 17
iptables -A INPUT -p icmp --icmp-type 18