[mdlug] Any good resources for IPTables?

[Jim Broughton]

On 08/23/2011 02:55 PM, Robert Adkins II wrote:
> I'm looking for some good resources that have a decent breakdown of the
> syntax of existing chains as well as how to build chains. I don't mind
> picking up a book on the subject. I have dug through a handful of online
> resources, but I have been finding them wanting in terms of how the
> information is presented.
>
>      Thanks,
>      Rob
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>

Are you looking to build custom chains or just work within the standard set?

I have written a few small firewall scripts and I have found your best bet is the
man page for iptables itself. The first thing you have to do is write down a 
description
in English as to exactly what you wish to accomplish. As in... If an incoming 
packet
from ip address xxx.xxx.xxx.xxx is trying to initiate a connection to port 25 
should
it be allowed through. Or I don't want any connections to port 22 except for 
these ip address or
this ip range that I determine should be able to connect.

I find that being able to look at examples is a great way to learn so...

Perhaps if you threaten me enough I'll even send you a modified for safety 
version of one that has
been keeping a couple of my administered sites safe for over 5 years.
The firewall contains some good examples of connection logging, limiting 
connection hits, nat,
port forwarding with and without logging and country blocking.