[CentOS] CentOS or other Linux Internet Router/Gateway

[Robert Heller]

At Sun, 22 Aug 2010 17:48:14 -0500 CentOS mailing list <centos at centos.org> wrote:

> 
> Hi Everyone,
> 
> I've got kids who are growing older and I want to build a Linux box to
> filter Internet access. I've got six computers on the Internet, plus
> the laptops -- most run Windows. I'm not sure if it's called a router
> or gateway or...?  I don't mind doing the leg work, I just don't know
> where to start. I'm pretty sure I'm *not* looking for a web server
> (though it might be fun to have a local web) -- I might also use the
> computer for a file server, but I mostly want a... proxy server? Not
> sure what tool I need to use. I seem to remember there were specialty
> Linux distributions for this purpose.
> 
> Once I do figure out what kind of box I'm building, would I still be
> able to put my Linksys router behind it, or would the Linux box *be*
> the router? -- and would I have to get a wireless switch instead?
> Would a Pentium III handle this duty, or would it gum up the works and
> make the Internet too slow?

It depends. The CentOS box could be a router.  Typically you'd have two
NICs (Network Interface Cards), one connecting to your
cable/DSL/whatever 'modem', and the other to your LAN.  Your Linksys
router would then become merely a switch and wireless AP.  You would
probably disable the Linksys router's dhcp server and on-board caching
name server, and transfer these functions to the CentOS box.  Ditto for
the firewall.

CentOS can also run a 'proxy' server, which could be used to filter /
block / etc. access to web sites eg it could be used to limit 'teenage'
access to certain sorts of websites for various reasons, including
traffic limitations (no Youtube/iTunes video/audio downloads while
daddy/mommy needs to use VPN to connect with the office, no IM'ing
after bedtime on school nights, etc.).  With the addition of the shaper
module, you can also create a separate 'teen' virtual network with limited
bandwidth. 

Your Linksys router IS a simple 32-bit computer running Linux (typicall
an ARM processor, not really any faster than a PIII, probably slower
actually). A PIII has more than enough processing power to function as a
router, DNS, and DHCP server.  And probably as a proxy server too.  The
proxy server's limitations would mostly be a matter of fast enough disk
access, partitularly if it was set up as a caching proxy server.

> 
> Sorry for stupid questions. At some point I'm going to have to learn
> about Linux servers. I'm hoping this project will help me get started
> on that.
> 
> Thanks for any pointers.
> 

-- 
Robert Heller             -- 978-544-6933
Deepwoods Software        -- Download the Model Railroad System
http://www.deepsoft.com/  -- Binaries for Linux and MS-Windows
heller at deepsoft.com       -- http://www.deepsoft.com/ModelRailroadSystem/