Is your firewall blocking connection from a host and still you want to unblock the IP address of the remote host? Here is one way of doing it:
1. Do a listing of firewall rules and grep the IP (eg. 188.8.131.52)
$ /sbin/iptables -L INPUT -n –line-numbers | grep 184.108.40.206
-write down the line number.
-If the chain name is different or user defined, replace “INPUT” by the relevant chain name such as OUTPUT.
2. Delete the line number (eg. for line number 99 and chain INPUT)
$/sbin/iptables -D INPUT 99
@credit to: http://www.cyberciti.biz/faq/iptables-delete-ip-address-subnet-from-linux-firewall/