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I'm considering putting OpenBSD on a netbook for use as a firewall. I am entertaining the idea of using a netbook because it has a built-in screen and keyboard, built-in battery backup, and a relatively small physical footprint. The firewall will be for a small office (i.e. <20 computers).

I'd like to know what drawbacks there are to using a netbook as an OpenBSD firewall -- and what alternatives I might wish to consider. One apparent drawback is that netbooks rarely (if ever?) have two ethernet ports, so a USB-Ethernet adapter will be required. What other pros/cons/issues ought to be considered when looking at an OpenBSD netbook firewall?

Thanks for reading. I'm grateful for your thoughts, and look forward to reading your feedback.


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Is this for home or work? (if for home, go for it) You should be able to run the firewall on a single NIC, havent looked at it in years. If the firewall fails, how much of a bother is it to put up a replacement or work without a firewall on the boundary? – samt Dec 9 '10 at 14:10

Your line of thinking is great, but what you really want is a server that has:

  1. The same Atom processor family as a netbook, for power consumption in the single-digit watts. This ensures that it will have a very long run time in the event of a power outage, even when plugged into a very inexpensive desktop UPS. Dual-core wouldn't hurt.

  2. Integrated KVM-over-IP, so you can access its console from anywhere on the network (or even remotely by VPN) so you never need to plug in a keyboard and a mouse.

  3. Dual network interfaces (and a PCIe slot so you can add more if the need arises, e.g. for a DMZ or a guest wireless network).

  4. Small form factor.

  5. Very low price.

The Supermicro SYS-5015A-PHF has all of these features, so it's a good place to start. It is available for around $350 (more like $425-450 once you've added 2GB of RAM and a hard drive) at Newegg,, and other reputable vendors.

[edit] The older SYS-5015A-H is an even less expensive option at around $250, but it does not support KVM over IP.

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@Miles Erickson: This is great advice. I've one concern, really: Presuming physical access is never an issue so point #2 gives no advantage, that the network connection is DSL (i.e. USB-Ethernet won't be maxed out) so point #3 gives no advantage, that the netbook has all the other points as well, and given that you can get a netbook for $250 all-in, what advantage is there to the server option? Reliability? If that's the only significant advantage - in this context - is it worth paying nearly double the price for the difference in reliability? Or are there other advantages? Thanks! – Brian M. Hunt Nov 8 '10 at 18:08
You do get a dual core processor and a great deal more flexibility for future upgrades. If you don't need KVM over IP, there is a slightly older model that costs about $100 less. – Skyhawk Nov 8 '10 at 18:59
@Miles Erickson: Thanks for the reply. The $100 I'd save on KVM over IP I'd have to spend on a monitor & keyboard. ha! I like the idea of these mini-servers, but for the price I'm not compelled that it offers a decided advantage over a cheap netbook - for the job at hand. A network that was much bigger and I'd consider one of these servers. – Brian M. Hunt Nov 8 '10 at 21:35
Obviously, you can and will make your own call on the hardware, but it is definitely unconventional to use a netbook as a firewall. If a supervisor or client ever asked me to do such a thing, I would decline to participate. The main problem with this type of a solution is that it looks unprofessional: any problems with the internet connection, whether connectivity or security, will forever get pinned on the guy who decided that 15 users should depend on a netbook for their internet access. Appearances really do matter. – Skyhawk Nov 8 '10 at 21:44
Also, it is not really necessary to buy a monitor and keyboard for occasional administration of a server that lacks KVM over IP. One just borrows whatever is available. Or, if you'd like a few free CRTs, I know plenty of people who will pay you five or ten bucks for every one that you're willing to pick up... – Skyhawk Nov 8 '10 at 21:46

Use PFsense.. its amazing.. Check it out.. I use it everywhere i can :D

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It really does come down to hardware and driver availability. The processing is typically adequate, hardware and driver support for different NICs to accommodate different networking speeds and/or media types may be challenging. You may also consider the inherent inefficiencies of USB 2.0 when attempting to drive multiple devices and/or devices beyond 480 mbps.

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Although the netbook has a battery, does the switch/router/gateway device have battery power? If not, this is one of the advantages which don't matter. Not sure I would trust what is basically your entire internet access for your office on netbook hardware. They are not build for this type of work- you only need a power supply problem/hard drive etc to fail, and you have no internet in your office.

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Have you considered using a small mini-itx (or smaller) embeded computer with a serial port?

A serial ports gives you console access from you PC or any other laptop nearby. The footprint is lowered, but you still have easy screen+keyboard access to it (without needing to remove a keyboard/monitor from somewhere else.

A netbook may be cheaper though, but good luck with the second ethernet port.

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