Recent fragility with if_wi, 802.11 adhoc/wep, and Tiger
Robert Watson
rwatson at FreeBSD.org
Wed Jul 20 08:10:07 GMT 2005
On Tue, 19 Jul 2005, Sam Leffler wrote:
>> I fairly regularly use 802.11 adhoc with WEP to communicate between my
>> 6.x/7.x FreeBSD notebook using if_wi, and my Apple PowerBook running
>> Mac OS X Tiger. A few days ago, when I updated from a June to a July
>> HEAD revision, this became quite "fragile". Specifically, I often find
>> that the Mac can't send to the FreeBSD box (ARP fails, etc), and that
>> sometimes it will give an error when I ask it to re-connect to the ad
>> hoc network. I find that if I ifconfig down/up if_wi, and likewise turn
>> off and on the wireless on the PowerBook, it seems to recover. I've
>> not had a chance to really try and diagnose this at all -- i.e., does
>> tcpdump show packets on either end, 802.11 state machine, etc. I was
>> wondering if anyone else has seen this problem, though.
>
> You didn't provide any config info. I recently noticed the wi driver
> isn't hooked up properly to the net80211 layer causing link state events
> to not be done properly (it appears disassoc events were being generated
> but not assoc/reassoc events). If you're using dhclient+adhoc mode then
> this might be related.
It's an entirely manual configuration job:
#!/bin/sh
ifconfig wi0 ssid network wepmode on weptxkey 1 \
wepkey 1:0xaaaaaaaaaaaaaaaaaaaaaaaaaa
ifconfig wi0 mediaopt adhoc
ifconfig wi0 inet 192.168.11.1
ifconfig wi0 up
ipfw delete 5005
ipfw add 5005 allow tcp from any to any via wi0
Previously, this worked without a hitch, and I'll normally transfer
several gigabytes of data. Now it works for some period, then appears to
wedge. It will then recover after a few minutes, usually 5-10 minutes.
Robert N M Watson
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