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I have some systems running on Ubuntu in the private IP range 192.168.2.0-255 . These systems are connected to a switch and the switch is connected to the ISP's modem.

Neither the switch nor the modem support firewall options. I don't have any firewall device and I'm not willing to individually configure firewalls on all the systems (via gui/iptables).

Is it possible to make an Ubuntu system into something like a software firewall, so that all the traffic/packets sent to or from the WAN(internet) would be allowed/denied based on its firewall rules?

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  • sudo ufw enable
    – Anonymous
    Nov 17, 2011 at 20:52

3 Answers 3

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AFAIK almost every distribution can be set as a firewall. And also there are some distro specifically built for this purpose such as zentyal, clearos etc. 'zentyal' is based on Ubuntu while 'clearos' is based on Centos.

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  • I"ll give a try of them
    – user3215
    Feb 24, 2011 at 1:28
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Firestarter Install Firestarter

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  • Option to whitelist or blacklist traffic
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  • Is it possible to manage or administer remote computer firewall setting rules with firestarter?
    – user3215
    Feb 24, 2011 at 1:27
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You can install Gufw

It's an easy to use free application to configure Ubuntu's internal firewall (Netfilter).

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  • 2
    Please note that this will ONLY be effective if the computer sits between the modem and the switch. You can't just have it hanging off the switch like all the other boxes and expect it to be able to block packets heading towards them. #obvious-but-worth-stating
    – Jeremy
    Oct 14, 2010 at 7:24
  • Also, you will have to check if netfilter sets the ip_forwarding option in the kernel. If not, please see this: ducea.com/2006/08/01/how-to-enable-ip-forwarding-in-linux
    – Jeremy
    Oct 14, 2010 at 7:25
  • One more thing. Not all software firewalls are equal, depending on what you want to be doing. It's worth looking into the differences between iptables, netfilter and pf.
    – Jeremy
    Oct 14, 2010 at 7:26
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    Is it like that installing Gufw on a single system I can handle the firewall settings on remote systems which are on the same network?.
    – user3215
    Oct 14, 2010 at 8:39

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