[TriLUG] help setting up Nextel BPL modem under Linux

[Joseph Mack NA3T]

I've got this modem working with the CD provided for windows and am now
trying to get it run under Linux. Nextel tech help is hopeless and it
takes 30mins on the phone to even get anyone who is hopeless.

Nextel is deploying BPL (broadband over power line) in the RTP area as a
test for later deploying it elsewhere in the country. The modem looks like
a wifi WAP except with only one antenna. The link seems to be over the
power line or phone lines, don't really know how it works.

The CD for Windows appears to contain only a monitoring gui. The actual
connection to the modem (and retrieval of gateway and dns servers info)
seems to be setup by dhcp. It doesn't appear to be pppoe or anything fancy
(no username/passwd).

The problem I'm having is the the IP you get by dhcp is not on the same
network at the default gw and I don't know how to route to the default gw
under linux. Windows doesn't have a problem with this but I don't know
why.

The link layer seems fine (can retrieve dhcp info in both Linux and
Windows)

Here's the IPs I get by dhcp (same under Linux/Windows)

my static IP=65.76.244.243/24
default gw  =172.29.251.133
DNS         =172.29.251.x and y (two entries)
dhcp server =172.30.30.128 (assume is an IP on the modem)

ipconfig under windows shows only the static IP on the NIC and the
127.0.0.1 on lo, so nothing fancy here.

Since routing isn't via an IP on the modem, I assume the modem is a
bridge.

When the windows machine is setup, I can connect through the modem and
make tcp connections to the outside world (eg ftp, run nslookup). I can't
ping the default gw, the DNS machines, or the dhcpserver. I can ping
outside machines (eg www.duke.edu). I didn't know the equivalent of
traceroute under windows (it's tracert I find), so I didn't get to
determine the routing to the outside world went by the default gw. I can
imagine that they might want to turn off pinging to the DNS machines, but
it's not obvious why they'd turn off pinging for the default gw.

Here's the output of `route print` on the windows box

dest           mask    gw            if

0.0.0.0        0.0.0.0 172.29.251    65.76.244.243
65.76.244.243  255^4   127.0.0.1     127.0.0.1
65.255.255.255 255^4   65.76.244.243 65.76.244.243
255^4          255^4   65.76.244.243 65.76.244.243
gw 172.29.251.133

does anyone understand how packets are being routed from 65.76.244.243/24
on the NIC to the default gw at 172.29.251.133? The top line here
is the usual default gw line as seen by `route` in unix, except
that in unix the two addresses must be in the same network.

Under linux I can't install the default gw - I get "no route to host"

I've heard that you can just dhcp from an OSX box too and get connected
without doing anything special, so it's got to be fairly simple, if only I
can figure out what "simple" is. The person who told me about doing it on
OSX didn't know what the routing table looked like.

Thanks Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!