Re: How to use if_bridge

"Daniel O'Connor" <doconnor@xxxxxxxxxxxx> wrote:

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

What's the intention behind the last step
and why did you have to create bridge0 twice?

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)

If you didn't already, you have to set net.inet.ip.forwarding.

Depending on your firewall setup you might have to disable
some of the net.link.bridge sysctls as well.

Fabian
--
http://www.fabiankeil.de/

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