[lug] actiontec 1520 / bridging / linux

D. Stimits stimits at attbi.com
Thu Aug 22 19:20:04 MDT 2002

Ben Luey wrote:
> Qwest just switched from using Cisco 678 modems to ActionTec 1520 -- are
> these modems linux compatible / what are people's experiences with these
> modems? How do you configure these modems -- ethernet/ip? Also, my ISP is
> the U of Colorado and the modem is going to be in bridging mode. Will the
> modem do the authenticating, or does each connected computer need to get
> authorized somehow? Does each connected computer (directly to the 1520, no
> hub / router) get its own ip address (that will occasionally change?) via
> dhcp?
> Thanks,
> Ben

I just set up a bridge (linux) to work with cable modem. The bridge is 
invisible to the outside world, it is unaware of protocols, and does not 
even need an IP address on any NIC. It forwards transparently between 
two interfaces, in promiscuous mode. I have no idea about your 
particular modem, or the university (when I was there they still used 
SLIP). If it is a bridge, then the computer or computers attached to it 
get their own IP. Auth and other is completely up to the individual PC 
if this is typical. The linux bridge can be set to do some filtering, 
e.g., the local bridge I have so far filters out all port 137-139, and 
port 111 (more can be done, those are just examples). If you attach a 
switch to the bridge, then each machine on the switch should get its own 
IP (I am assuming it uses DHCP and has been set in some admin office to 
some maximum number of MAC addresses being given an IP address).

D. Stimits, stimits AT attbi.com

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