Wireless DHCP issues

["Marco Trevisan (Treviño)"]

Hello since long time (always I guess) I have had problems when I tried
to get an IP using DHCP from some APs.

At the beginning I thought that this was just an issue of one of my
wireless routers (a Motorola WR850GP running dd-wrt), but recently I
verified that I was unable to make the DHCP working with many free APs I
tried (at the university, at the pub...).

Practically, I associate with the AP (iwconfig confirms me it, but also
the AP), but when I try to get an IP I simply don't get any dhcp-offer
(or the phone doesn't grab it!), as you can see:

root at om-gta02:~# udhcpc eth0
udhcpc (v1.11.1) started
Sending discover...
Sending discover...
Sending discover...
Sending discover...
Sending discover...
[...]

root at om-gta02:~# dhclient eth0
Internet Systems Consortium DHCP Client V3.0.2
Copyright 2004 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/products/DHCP

Listening on LPF/eth0/00:12:cf:8e:ef:4b
Sending on   LPF/eth0/00:12:cf:8e:ef:4b
Sending on   Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 6
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 14
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 15
[...]

If now I configure my network manually with ifconfig, route, resolv.conf
(if I know the needed informations) as expected - I can connect with no
problems.

So, the wireless association works well with any router. With some ones,
unfortunately, I can't use the DHCP (also if, of course, the router
supports it and I am able to get an IP using another device).

I've tested this with Om2008, Debian, Android... Every distro has the
same problem.

I wanted to understand better this by running a packet sniffer while my
notebook was in monitor-mode to understand what's happening, but I had
no time (and who knows when I'll have :().

Werner, maybe have you done some research about this too?

-- 
Treviño's World - Life and Linux
http://www.3v1n0.net/