H do I stop Iptables firewall under Debian Linux server system?

The iptables command is used to set up, maintain, and inspect the tables of IPv4 packet filter rules in the Linux kernel.

Several different tables may be defined. Each table contains a number of built-in chains and may also contain user-defined chains. You can use the following commands to stop firewall under Debian Linux.

Syntax

First you need to login as root user.

If it is a remote server login over the ssh session using the following syntax:
$ ssh user@server1.cyberciti.biz
The syntax is as follows:

iptables options
iptables -X
iptables -F
iptables -t table -X
iptables -t table -F
iptables -P chain ACCEPT

To flush the selected chain or all the chains in the table pass the -F option to iptables command. This is equivalent to deleting all the rules one by one. To delete the optional or all the user-defined chain pass the -X option to iptables command. You also need to delete nat and mangle tables using the -F and -X options. Finally, set the default policy to ACCEPT.

Example

Type the following command to save existing iptables configuration.
iptables-save > /root/working.iptables.rules

To stop firewall type the following commands (see syntax above for detiled information):

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

You can also use this shell script to stop firewall.