Questions about network topology and 802.11

Questions about network topology and 802.11

Post by EE » Sat, 02 Aug 2003 17:05:24



I am trying to run a RH linux machine as a firewall/gateway for 2 networks:
one wired and one wireless.  Currently, I have it set up for the wired part
and I have some questions about how to configure it to work properly with
another network.
First of all, can the two cards (assuming I can find a linux-friendly
802.11b card) be on the same network in the same DHCP address block?
Secondly, can I use a regular 802.11b card in ad-hoc mode or do I need to
purchase an Access Point?
Are there any special kernel compilation configuration option I need to
select for 802.11b support?
If I cannot run the network as I have planned, are there alternate
topologies that would work?  How about keeping the gateway as a gateway for
the wired portion and having a wireless router as a client of the gateway?
Would nodes under the wireless router and nodes under the gateway be able to
communicate?
Finally, are there any 802.11b cards that work well (or just work) under
linux?

Thanks in advance for your responses,
EE

 
 
 

Questions about network topology and 802.11

Post by Allen Kistle » Sun, 03 Aug 2003 00:53:39



> I am trying to run a RH linux machine as a firewall/gateway for 2 networks:
> one wired and one wireless.  Currently, I have it set up for the wired part
> and I have some questions about how to configure it to work properly with
> another network.
> First of all, can the two cards (assuming I can find a linux-friendly
> 802.11b card) be on the same network in the same DHCP address block?

No.  You'll be using your Linux box as a router between two networks, so
pretty much by definition they have to be different networks.

Quote:> Secondly, can I use a regular 802.11b card in ad-hoc mode or do I need to
> purchase an Access Point?

If you can get an 802.11b card to work, that should be all you need.
However it would be a much more flexible design to use an Ethernet
adapter plugged in to an AP with a crossover cable.  Finding an Ethernet
card that works with Linux is pretty easy.  The AP won't care what's on
the other end of the wire.

The setup I described is essentially what I do at home.  I use a Belkin
AP which provides no DHCP services to the wireless clients.  I use the
Linux box as the DHCP server.  The only drawback to the AP is that the
management software is Windows-only, as I think you'll find with most
APs, except high-end ones with their own command line.  VMware to the
rescue on that point, anyway.

Quote:> [snip]


 
 
 

Questions about network topology and 802.11

Post by /dev/rob » Sun, 03 Aug 2003 02:54:44




Quote:>> First of all, can the two cards (assuming I can find a linux-friendly
>> 802.11b card) be on the same network in the same DHCP address block?

> No.  You'll be using your Linux box as a router between two networks, so
> pretty much by definition they have to be different networks.

You CAN configure the two NIC's to work as a bridge, in which case. yes,
the wired and wireless networks can be in the same subnet. That's
exactly what our WAP's are doing. Like yours, my WAP forwards DHCP
requests to the wired dhcpd on Linux.

Quote:>> Secondly, can I use a regular 802.11b card in ad-hoc mode or do I need to
>> purchase an Access Point?

[to the OP] Ad-hoc mode should work, but a WAP is easier.

Quote:> If you can get an 802.11b card to work, that should be all you need.
> However it would be a much more flexible design to use an Ethernet
> adapter plugged in to an AP with a crossover cable.  Finding an Ethernet

My WAP doesn't care about the cable type. I use patch cables both for
WAP-to-NIC and for WAP-to-hub/switch.

Quote:> The setup I described is essentially what I do at home.  I use a Belkin
> AP which provides no DHCP services to the wireless clients.  I use the
> Linux box as the DHCP server.  The only drawback to the AP is that the

I had to turn off DHCP service on my WAP, but I was able to do so
easily. For physical connections, which is what I think the OP is
interested in, I plug everything into the LAN ports on the WAP.

Quote:> management software is Windows-only, as I think you'll find with most
> APs, except high-end ones with their own command line.  VMware to the

These days I think more of them are going toward the HTTP model. Mine
does, anyway, and it was the cheapest I could find. It says it requires
MSIE or Netscape, but it works with Opera and Konqueror too.
Unfortunately lynx was a no-go. :)
--

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