[clug] anyone using a Linux as an Internet gateway?

[Angus Gratton]

On Tue, 2010-10-19 at 18:15 +1100, Daniel Pittman wrote:
> > I'm wondering is there any performance factors for a PC vs a router/modem
> > etc..  ie is a PC a faster firewall and router?
> 
> No.  I mean, technically, yes, but unless you have at least a Gigabit
> connection from your ISP (and the data center to match) then you are moving so
> little data that it will make no practical difference.

I think this is generally true, but there are some limits you can hit
even on a small router.

I have a Fonera (180Mhz MIPS wireless router, 16Mb RAM, ie similar to
most consumer routers.) It's running OpenWRT (Linux) and acting as my
ADSL router. If you have enough concurrent NATed TCP connections (ie
20ish), the CPU will get pegged masquerading packets and limit
throughput, before the ADSL2 link itself gets saturated.[1]

It's a corner case, but it can definitely happen. NAT takes quite a bit
of CPU processing compared to just moving packets, and the small MIPS
processors don't have a lot of power to spare.

That said, I've never thought about using a more powerful box to do the
job. It works fine for normal use, and with OpenWRT you get the
advantage of being able to treat the router like a "real" Linux box. If
you do a lot of torrenting, you might think differently. :)


- Angus


[1] There's probably some fine-tuning I could do in OpenWRT's default
"firewall" iptables config to get this number up a bit, I just haven't
felt the need to mess around. :)