Jul 05, 2013

Is an outbound firewall necessary?

I didn’t realize until today that Macs don’t have an outbound firewall. Is this something to be concerned about for a personal use machine?

Is an outbound firewall needed?

"Firewalls protect you from the certain classes of bad things out on the internet.

Note that's "protect you from them". That implies that the primary function of a firewall is to prevent bad stuff "out there" from reaching or affecting your computer.

My preference is to use a hardware device such as a router with NAT (Network Address Translation) enabled. This does an incredibly effective job of hiding your computer from outside access. You can connect out, but outside computers cannot initiate a connection without your having explicitly configured your router to allow it.

Using a router also takes the burden of that work off of your computer. In fact, a single router can act as a single effective inbound firewall for all the computers that are connected behind it.

An "outbound" firewall looks for threats originating on your computer attempting to connect out to the internet. In a sense, it's "protecting them from you". While that may be very generous of you to protect everyone else from your computer, the real difference is that it will presumably block and more importantly tell you when something suspicious is happening so that you can take corrective action."

I’d say, no, it isn’t really necessary. A solid inbound firewall is obviously important, but outbound firewalls have little demonstrated benefit that I’ve seen. I guess it could help prevent your machines from spewing out spam (which means you have other problems if you don't work at Spam R US), assuming the outgoing firewall could distinguish between the spam and legit traffic. Others may disagree. Here is an article on the topic that you might like:


Answer this