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The Problem:

As big as Ubuntu is, I am really surprised there is no firewall included by default. Yes, I know that the functionality is built into the kernel, but do you think half of these newbs running Ubuntu know about iptables?

The Solution:

Guarddog is a GUI Linux iptables/ipchains configuration utility. This is going to save you from having to spend hours of reading about Linux firewall setup and setting up rc scripts, etc.

sudo apt-get install guarddog

Now you have a menu item under Applications -> Internet -> Guarddog. It is pretty much useless unless you are running as a superuser, so run

sudo guarddog

You should get a prompt about not having a rc.firewall, click ok.

Guarddog’s philosophy is to block if not allowed, just like any firewall. Keep this in mind if you go to try to play AssaultCube and it won’t connect.

Guarddog 1

The first screen contains your zones. There should be two setup; Local and Internet. This should be fine for a home workstation.

Guarddog 2

Next, select the Internet Zone and go through and put a check next to every application that you use. This is probably what you need for basic functionality:

Data Serve -> NTP
File Transfer -> FTP
File Transfer -> HTTP
File Transfer -> HTTPS
Mail -> IMAP
Mail -> SMTP
Mail -> POP3
Network -> DNS
Network -> Ping

It is not needed to select anything under the Local zone, unless you have incoming connections for some reason. Common uses would be SSH and bittorrent.

Guarddog 3

I unchecked everything under Logging. I would recommend leaving it off unless you are having issues or someone is trying to hack your system.

Guarddog 4

Make sure you check enable DHCP if needed and the interface name is correct. You may specify any custom ports here if you are running an application that is not listed on the Ports tab.

Go ahead and click Apply and you should have a working firewall. Congrats on your new Ubuntu with a firewall enabled and if you want (look but don’t touch) take a gander at the script in /etc/rc.firewall. Looks like Guarddog generated more code than I could have wrote in a week.

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2 Comments

  1. femtolicious » links for 2007-11-21 Says:
    November 20th, 2007 at 10:35 pm

    [...] Security: Enable a Firewall on Ubuntu with Guarddog (tags: ubuntu linux security) [...]

  2. pullareddy Says:
    August 17th, 2008 at 2:56 pm

    thanks……….. urs posting is very helpful. i have a problem in hiding my ip. plese send any post regarding hiding ip. with good explanation…
    thanks…once again

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