How To Use iptables for Linux Firewalls

How To Use iptables

You can start, stop, and restart iptables after booting by using the commands:
# service iptables start
# service iptables stop
# service iptables restart


To get iptables configured to start at boot, use the chkconfig command:.
# chkconfig iptables on

You can determine whether iptables is running or not via the service iptables status command. Fedora Core will give a simple status message. For example

# service iptables status

iptables Won't Start

# touch /etc/sysconfig/iptables
# chmod 600 /etc/sysconfig/iptables
# service iptables start

Example : Allowing WWW And SSH Access To Your Firewall

#---------------------------------------------------------------
# Allow previously established connections
# - Interface eth0 is the internet interface
#---------------------------------------------------------------

iptables -A OUTPUT -o eth0 -m state --state ESTABLISHED,RELATED \
 -j ACCEPT

#---------------------------------------------------------------
# Allow port 80 (www) and 22 (SSH) connections to the firewall
#---------------------------------------------------------------

iptables -A INPUT -p tcp -i eth0 --dport 22 --sport 1024:65535 \
 -m state --state NEW -j ACCEPT
iptables -A INPUT -p tcp -i eth0 --dport 80 --sport 1024:65535 \
 -m state --state NEW -j ACCEPT

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