Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Mail Systems
Eclipse Documentation

How To Guides
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Problem Solutions
Privacy Policy




Appendix A. Detailed explanations of special commands

A.1. Listing your active rule-set

To list your currently active rule-set you run a special option to the iptables command, which we have discussed briefly previously in the How a rule is built chapter. This would look like the following:

iptables -L

This command should list your currently active rule-set, and translate everything possible to a more readable form. For example, it will translate all the different ports according to the /etc/services file as well as DNS all the IP addresses to get DNS records instead. The latter can be a bit of a problem though. For example, it will try to resolve LAN IP addresses, i.e., to something useful. is a private range though and should not resolve to anything and the command will seem to hang while resolving the IP. To get around this problem we would do something like the following:

iptables -L -n

Another thing that might be interesting is to see a few statistics about each policy, rule and chain. We could get this by adding the verbose flag. It would then look something like this:

iptables -L -n -v

Don't forget that it is also possible to list the nat and mangle tables. This is done with the -t switch, like this:

iptables -L -t nat

There are also a few files that might be interesting to look at in the /proc file system. For example, it might be interesting to know what connections are currently in the conntrack table. This table contains all the different connections currently tracked and serves as a basic table so we always know what state a connection currently is in. This table can't be edited and even if it was possible, it would be a bad idea. To see the table you can run the following command:

cat /proc/net/ip_conntrack | less

The above command will show all currently tracked connections even though it might be a bit hard to understand everything.

  Published under the terms fo the GNU General Public License Design by Interspire