How to allow/block PING on Linux server – IPTables rules fo
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<div class="post-content-left"> ?-?APRIL,9TH 2014 The ‘PING’,it’s a command-line tool to check a host is reachable or not. We can manage it by the help of ‘iptables’. The ‘ping’ is using ICMP to communicate. We can simply manage the ‘icmp : Internet Controlled Message Protocol’ from iptables.Required iptables switchesThe below pasted switches are required for creating a rule for managing icmp. -A : Add a rule -D : Delete rule from table -p : To specify protocol (here 'icmp') --icmp-type : For specifying type -J : Jump to target Normally using icmp types and its Codes Click here for ICMP Types and Codes echo-request : 8 echo-reply : 0 Here I am explaining some examples. How to block PING to your server with an error message ?In this way you can partially block the PING with an error message ‘Destination Port Unreachable’. Add the following iptables rules to block the PING with an error message. (Use REJECT as Jump to target) iptables -A INPUT -p icmp --icmp-type echo-request -j REJECT Example: [root@support ~]# ping 109.200.11.67 PING 109.200.11.67 (109.200.11.67) 56(84) bytes of data. From 109.200.11.67 icmp_seq=1 Destination Port Unreachable From 109.200.11.67 icmp_seq=2 Destination Port Unreachable From 109.200.11.67 icmp_seq=3 Destination Port Unreachable To block without any messages use DROP as Jump to target. iptables -A INPUT -p icmp --icmp-type echo-request -j DROP iptables -A OUTPUT -p icmp --icmp-type echo-reply -j DROP Allow Ping from Outside to Inside iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT How to block PING from your server to world ?In this way you can block PING option from your server to outside. Add these rules to your iptables to do the same.Block PING operation with message ‘Operation not permitted’ iptables -A OUTPUT -p icmp --icmp-type echo-request -j DROP Example: root@test [~]# ping google.com PING google.com (173.194.34.136) 56(84) bytes of data. ping: sendmsg: Operation not permitted ping: sendmsg: Operation not permitted ping: sendmsg: Operation not permitted ping: sendmsg: Operation not permitted To block with out any error messages.For this,DROP the echo-reply to the INPUT chain of you iptables. iptables -A OUTPUT -p icmp --icmp-type echo-request -j DROP iptables -A INPUT -p icmp --icmp-type echo-reply -j DROP Allow Ping from Inside to Outside iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT You can use the icmp code instead of icmp-type name for adding rule to iptables.That’s it. Try this and let me know your feedback. reference:http://crybit.com/iptables-rules-for-icmp/ （编辑：淮北站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
