[OLUG] {OT}Network questions

[Phil Brutsche]

A long time ago, in a galaxy far, far way, someone said...

> I've been playing with two computers networked through a cross over
> cable.  I've got a P75 I want to set up as a firewall now and start
> working with IPchains.  I've read through the Ethernet HOWTO and I
> still have some questions about the hardware.  I've got two NICs that
> run at 10Mbps.  I need to buy another NIC so I was wondering if there
> is any reason to purchase one that runs 10/100Mbps?  I mean I will
> have two computers hooked into the firewall.  For my small system is
> 100Mbps really needed?

No, you don't need another NIC unless your internet connection is a cable
modem or DSL line.  If, for some reason, you do need another NIC, go for
the 10/100 - these days they seem to be easier to find that an 10Mbps-only
card, and are generally faster than a 10Mbps card anyway (10/100s are
typically better designed since they need to get data to the card real
fast anyway for 100Mbps mode, which has the side effect of speeding up
10Mbps connections).

> I also understand you can use two NICs on your firewall computer one
> hooked to the internet instead of using a modem.  Would this be faster
> than hooking up to the net with a modem?  At this point my network won't
> be hooked up 24-7, basically a dial up.  How does a person hook into a
> phone line with a NIC given the cables are different?

That part I think you misunderstood.  This is your network now:


  -------------                               -------------
  |           |     Crossover cable           |           |
  | Linux     |-------------------------------| Another   |
  | System    |                               | System    |
  |           |                               | (Windows?)|
  -------------                               -------------

Since you want the Linux system to be a firewall, all it needs is *another
network connection* - a plain 56k modem will work (although be very slow)
every bit as well as a network connection that uses an ethernet card (like
a cable modem or a DSL line).  Conceptually, the network would look like
this:

                  ---------------     Ethernet          ---------------
   Internet ------| Linux       |-----------------------| Windows?    |
                  ---------------                       ---------------

You _can_ have two NICs in your firewall, but the second NIC would be
unused if you have a plain modem.

Basically, you'll have an easier time of this if you forget about "Network
Interface Card" vs "modem", and think in terms of "network interface"
(that's all Linux cares about anyway), which applies to NICs as easily as
it does to modems.

> As far as the hub goes do you have to set things up under Linux to run
> a hub? I haven't come across anything that mentions installing a hub
> or anything.  Does the hub just take care of itself?  Do I have to
> worry about some hubs not working with Linux?  I'm using D-Link cards
> and I was thinking I would use one of their cheap hubs.

No setup is needed what so ever for any operating system to use a hub or a
switch.  You don't need to worry about an ethernet hub not working with
Linux, either - they're very dumb devices, and are sometimes called
repeaters.  This is because they repeat what they see on one port over all
the other ports.

-- 
----------------------------------------------------------------------
Phil Brutsche					pbrutsch at creighton.edu

"There are two things that are infinite; Human stupidity and the
universe. And I'm not sure about the universe." - Albert Einstein


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