Haha lagi mo mencoba menulis dalam bahasa inggris, pengen tahu dampaknya bagi trafik blog seperti apa ya…
The Internet Control Message Protocol (ICMP) is one of the main protocols of the Internet Protocol Suite. It is used by network devices, like routers, to send error messages indicating, for example, that a requested service is not available or that a host or router could not be reached. ICMP can also be used to relay query messages–(wikipedia).
ICMP commonly use by ping and traceroute command on your computer,
Ping : method to know whether one host (computer or other network appliance which has IP address) is live.
Traceroute : which path taken to a destination IP address or domain name
Because of the innocent of ICMP, the good purpose of ICMP has been miss use by hacker. Many hacker using technique based on ICMP protocol like Ping Sweep.
Ping Sweep, basic network scanning to determine which of range IP address map to live host (computers), or single ping that will tell you whether one specified host computer exist on the network. So once attacker knows which host are live, it can started the denial-of-service attack (ping of death), well it just one example.
So drop unneeded ICMP packet from outside source, is the first step to secure your network.
this is example on cisco router, to drop ICMP packet.
create access-list on your router,
access-list 111 deny icmp any any echo-reply
access-list 111 deny icmp any any echo
access-list 111 permit ip any any
and put the access-list on interface that connect your router to outside source.
ip address 188.8.131.52 255.255.255.0
ip access-group 111 in
and here is the result.