Then, when you are ready to use them again,
you read them back in using iptables-restore.
Although most Linux systems offer some sort of interface to manage and load your iptables firewall
automatically, very few offer the full range of features you might want. So you will need to understand
iptables to do some configuration by hand if you do more than simply open or close access
to ports. Just understanding iptables will help you go from one Linux system to another, regardless
of the interface an individual distribution will put on top of it.
Starting with iptables
If you have a running Linux system in front of you, you can immediately get a feel for how your
firewall is working in a number of ways. To go beyond just listing the current firewall rules, however,
I recommend that you try the procedure I describe in the next section on a Linux system that
is set up for you to play with. Booting KNOPPIX is a great way to try that procedure without doing
any harm (because everything disappears at your next reboot). Otherwise, just read along.
Setting Some Rules
Studying the following steps will help you understand the syntax of firewall rules and the types of
information you can set with them. This procedure is made to run from beginning to end on a
computer that you have complete control over.
Pages:
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925