If you are using other Linux distribution such as Debian / Ubuntu / Suse / Slackware Linux etc., try the following generic procedure. First, save the current firewall rules, type:

    iptables-save > /root/firewall.rules

OR

    sudo iptables-save > /root/firewall.rules

Next, type the following commands (login as the root) as bash prompt:

iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT 

Or create a shell script as follows and run it to disable the firewall: