[PLUG-TALK] Wireless in Munchkinland

Russell Senior russell at personaltelco.net
Thu Aug 30 18:22:41 UTC 2012


>>>>> "Bill" == Bill Barry <bill at billbarry.org> writes:

Bill> As you have diagnosed, the gateway is not in the subnet where
Bill> your ip address is. This is perfectly legal to do. The problem
Bill> is that the dhcp client is not handling that situation
Bill> correctly. The work around as suggested here

Bill> https://bbs.archlinux.org/viewtopic.php?id=72685 is to add a
Bill> route to the gateway

Bill> route add 74.5.120.9/32 dev wlan1

Bill> I had a similar problem with a /32 network in the Benton County
Bill> Library several years ago, so I know that the place to report
Bill> such bugs for the ISC dhcp client is dhcp-bugs at isc.org

The other possibility is that the network you were connecting to is
just completely broken.  That is not altogether uncommon either.

Nowadays, the dominant strategy for people who want tubes in random
places is to carry a smartphone that they can tether to in the absence
of friendly wifi networks.

The dominant strategy for people building networks is to create them,
declare victory, and wander away not too concerned about whether they
continue to work.  There is a dyslocation of pain and concern/ability
to do anything about it, which leads to long latencies between the
discovery and correction of problems.

See also: http://www.flykci.com/AirportService/WiFi/Index.htm
It turns out they have a help desk you can call.

If you really want to see what's happening, try capturing a packet
trace with tcpdump or wireshark of your conversation with the DHCP
server.  Then you can confirm what might be going wrong and you can
write a better bug report.

Something like:

  tcpdump -s0 -w/tmp/capture.pcap -i wlan1

Getting that started in time to capture the DHCP interaction is left
as an exercise for the reader, and will depend on you distribution and
how it manages network connections.  You can try manually firing off
the DHCP client if you know which one your distribution has/uses.

Then, look at the session with wireshark:

  wireshark /tmp/capture.pcap


-- 
Russell Senior, President
russell at personaltelco.net



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