[TriLUG] help setting up Nextel BPL modem under Linux

[Aaron S. Joyner]

Joseph Mack NA3T wrote:

>I've got this modem working with the CD provided for windows and am now
>trying to get it run under Linux.
>
Okay, first, to clear up a few misconceptions.  The Nextel service is 
not BPL based.  It's a 3G (3rd Generation) Cellular Network, in other 
words it operates in similar spectrum and off the same towers, as the 
regular Nextel Cellular service does.  So don't worry, your 10m band 
will be fine.  :)

You are precisely correct in that the "broadband modem" you have is just 
a bridge.  Also, if you're using the Static IP based service, you 
*probably* shouldn't be getting your address via DHCP.  You'll need to 
get a gateway address from Nextel that corresponds to your Static IP 
subnet - if I had to hazard a guess I'd bet on 65.76.244.254 or 
65.76.244.1  Try setting your gateway to one of those addresses, and see 
what you get.

Bottom line, from a purely networking perspective, you can't have a 
default gateway that a) is not on your local subnet or b) you don't have 
a static route to --- and b is really uncommon.  So uncommon that in my 
8 years in the ISP industry, I've never seen it done.  So let's hazard a 
guess that your default gateway really is accessible on the other side 
of that connection, and you can send it traffic directly.  What you'd 
need to setup in Linux is something like this:
# route add -host 172.29.251.133 dev eth0

...Which would give you something like this...
# route
Destination     Gateway         Genmask         Flags Metric Ref    Use 
Iface
172.29.251.133  *               255.255.255.255 UH    0      0        0 eth0

At which point you'd be able to add 172.29.251.133 as your default gateway.

Other, sneaky yet valid, options - try nmap'ing your entire subnet.  See 
what IPs respond, and try setting your default gateway to that IP 
address and pinging out.  :)  Check out "arp -a" - see what addresses 
end up in your arp traffic because they happened to be on the other end 
of the bridge.  Try setting your gw to those.

Above all, let us know what you come up with - I'd really like to hear.  
Also, if you want further help, I'll be at the meeting tonight w/ my 
working Nextel broadband connection.  :)  The only difference being that 
I don't have the static IP based service.

Aaron S. Joyner