Security

Frugal Install

Encryption

Definitions

Iptables 1
Set Up a Simple Firewall

Iptables 2
Simplify the Setup

Iptables 3
Start the Firewall Automatically

Iptables 4
Change the Policy to Drop

Iptables 5
Logging

Iptables 6
Add Rules

Iptables 7
IP Address Blocks

Iptables 8
Add Chains

Iptables 9
Change Rules While in Use

Iptables Summary

Graphical Firewalls

Check for Malware

Erase Everything from a Hard Drive

Security Links

Other Links

Contact Details

Iptables 8

Add Chains

Logging Multiple Rules

You may want to drop a number of IP addresses or blocks. You may also want to log everything you drop. The way things are so far, you need to have two rules for each, one for logging and the other for dropping.

Notice how long the list is getting. As you add more rules the list may get much longer.

Adding Chains

You can avoid having each rule twice by adding another chain. Let's call it LOGDROP.

To add this chain, open the Root Terminal and type:

This tells Iptables to create a new chain called LOGDROP. This only needs to be done once, unless you delete it, or reinstall the operating system.

If you type "iptables -L" you will now see INPUT, FORWARD, OUTPUT and LOGDROP chains.

You can use any name for the chain, and add more chains if you want.

Let's add rules to this chain.

These rules need to be added to the Iptables rules.

The rules above can now look like this:

Each rule only needs to be written once, which saves a lot of space, particularly as the list gets longer.

Notice the "-j" which has previously been followed by ACCEPT, DROP or LOG, now tells Iptables to "jump" to LOGDROP. LOGDROP tells Iptables to log the information then drop the packet.

If these new rules are added to the earlier rules, you should have:

Deleting Chains

Chains may also be deleted. They can only be deleted when they are empty. To delete everything from Iptables type:

To delete the chain LOGDROP, type:

© Copyright Guy Shipard 2008 - 2009