To clear all iptables entries, first stop fail2ban, then clear, then restart fail2ban
iptables --policy INPUT ACCEPT; iptables --policy OUTPUT ACCEPT; iptables --policy FORWARD ACCEPT;
iptables -Z; # zero counters iptables -F; # flush (delete) rules iptables -X; # delete all extra chains
To block:
iptables -A INPUT -s 43.0.0.0/8 -j DROP
To block a specific domain: iptables -I INPUT -p tcp --dport 80 -m string --string "Host: bc.googleusercontent.com" --algo kmp -j DROP
TO unblock
iptables -L INPUT --line-numbers
(locate the line number)
iptables -D INPUT 9 (where 9 is the line number)