How to remove IP block from Firewall ?

October 7, 2016 by No Comments

In computing, a firewall is a network security system that monitors and controls the incoming and outgoing network traffic based on predetermined security rules. There are so many reasons the ISP IP may be blocked in the server firewall. Following are the steps to troubleshoot the ip block issues

IP Block Algoritham

  • Is the ISP IP provided ?
    • If yes, check the firewall for the ip is blocked or not
      • If yes,
        • find the reason for the block
        • Remove the IP from the firewall
        • If it is customers dedicated IP and if he is told us to white list, do it.
        • Update customer with the the IP is blocked due to the above mentioned reason and suggest to avoid blocking again.
      • If no,
        • Check the log on, for any previous block or temperorly block
        • If nothing, tell him, there is no block
    • If no, Tell with the ip is not blocked.


Some of the reasons for the IP block are;

Failed password login ( cPanel / ftp / mail )
Too many Mod_security rule detected
Port Scan detected

If you are using csf ( Config Server Firewall ), following are the commands to check and remove the IP address.

# csf -g IPADDRESS       	-  For checking the Ip is blocked or not
# csf -d IPADDRESS       	-  Deny ip in the firewall
# csf -dr IPADDRESS  	        -  Remove blocked ip from the deny rules 
# csf -tr IPADDRESS	        -  Remvoe IP from the temperory block
# csf -a IPADDRESS	        -  Add IP to the white list