May 2013
Beginner to intermediate
384 pages
7h 40m
English
book
Linux Shell Scripting Cookbook, Second Edition - Second Edition
by Shantanu Tushar, Sarath Lakshman
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Basic firewall using iptables
A firewall is a network service which is used to filter network traffic for unwanted traffic, block it, and allow the desired traffic to pass. The most powerful tool on Linux is iptables, which has kernel integration in recent versions of the kernels.
How to do it...
iptables is present, by default, on all modern Linux distributions. We will see how to configure iptables for common scenarios.
- Block traffic to a specific IP address:
#iptables -A OUTPUT -d 8.8.8.8 -j DROPIf you run
PING 8.8.8.8in another terminal before running the iptables command, you will see this:PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_req=1 ttl=56 time=221 ms 64 bytes from 8.8.8.8: icmp_req=2 ttl=56 time=221 ms ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.