How to use if_bridge

[Daniel O'Connor]

I am trying to use if_bridge with OpenVPN and I am having some trouble with 
basic bridging.

I am testing it on my laptop with has an ath interface which uses WPA to a 
Linksys WRT54G and then to a FreeBSD gateway.

I have tried both configuring ath0 with an IP as well as bridge0 but neither 
work. It seems that none of the packets from ath0 appear on bridge0.
ie..
ath0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
        ether 00:90:96:c1:90:54
        media: IEEE 802.11 Wireless Ethernet autoselect (OFDM/48Mbps)
        status: associated
        ssid dons channel 6 bssid 00:13:10:9b:52:d4
        authmode WPA privacy ON deftxkey UNDEF TKIP 2:128-bit txpowmax 35
        protmode CTS burst roaming MANUAL bintval 100
bridge0: flags=8143<UP,BROADCAST,RUNNING,PROMISC,MULTICAST> mtu 1500
        inet 10.0.2.102 netmask 0xff000000 broadcast 10.255.255.255
        ether ac:de:48:67:74:b6
        priority 32768 hellotime 2 fwddelay 15 maxage 20
        member: ath0 flags=7<LEARNING,DISCOVER,STP>
                port 4 priority 128 path cost 55 blocking

When I run tcpdump..
[inchoate 20:35] ~ >sudo tcpdump -ni bridge0
Password:
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on bridge0, link-type EN10MB (Ethernet), capture size 96 bytes
20:35:30.586751 arp who-has 10.0.2.7 tell 10.0.2.102
[etc]

Whereas a tcpdump on ath0 shows no ARP packets..
I did the following to configure it..

killall devd [to stop it running dhclient]
/etc/rc.d/netif stop ath0
ifconfig bridge0 create
wpa_supplicant -i ath0 -c /etc/wpa_supplicant.conf
ifconfig bridge0 create
ifconfig bridge0 addm ath0
dhclient bridge0

I see the DHCPDISCOVER requests when I tcpdump bridge0 but they don't appear 
on ath0.

If I run dhclient on ath0 it works fine for normal traffic but I don't see any 
ath0 traffic on bridge0. If I create a tap interface (eg cat /dev/tap0) and 
add it to the bridge (ifconfig bridge0 addm tap0) it sees no packets either.

bridge0 appears to learn no addresses..
[inchoate 20:46] ~ >ifconfig bridge0 addr
[inchoate 20:46] ~ >

Am I missing something obvious?
(This is on -current as of 27 Mar)

PS please CC me as I am not subscribed to the list.

Thanks.

-- 
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C
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