Iptables Guide, Meaning , Facts, Information and Description

The iptables command and framework are used for defining the tables and rules for firewall. Iptables allows stateful packet filtering and network address translation (NAT). Netfilter connects iptables to the kernel.

Iptables works with Linux kernels 2.4 and 2.6. Older Linux kernels use ipchains (Linux 2.2) and ipfwadm (Linux 2.0).

Example

A workstation firewall.

# iptables -L
Chain INPUT (policy DROP)
target     prot opt source               destination         
ACCEPT     all  --  localhost.localdomain  localhost.localdomain 
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED 
ACCEPT     icmp --  anywhere             anywhere            icmp  destination-unreachable 
ACCEPT     icmp --  anywhere             anywhere            icmp time-exceeded 
ACCEPT     icmp --  anywhere             anywhere            icmp echo-reply 
DROP       all  --  anywhere             anywhere            

Chain FORWARD (policy DROP)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

$ lynx www.iki.fi/karvinen

$  ping -c 1 10.0.0.1
PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
--- 62.78.243.6 ping statistics ---
1 packets transmitted, 0 received, 100% packet loss, time 0ms

$ telnet 10.0.0.1 80
Trying 10.0.0.1...

External links

• The netfilter/iptables project - the official homepage.
• Firewall for Single Host with Iptables - a script to use iptables firewall.

This is an Article on Iptables. Page Contains Information, Facts Details or Explanation Guide About Iptables

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