Re: forwarding didn't work if wlan0 is member of a bridge

12.01.2016, 01:53, "Olivier Cochard-Labbé" <olivier_at_cochard.me>:
> After weeks of troubleshooting, at last I found how to reproduce this
> problem ;-)
Hi Olivier,
>
> Here is the setup:
>
> LAN0 <--> [(re0) fbsd router (bridge0 addm re1 addm wlan0)] <--> Wireless
> LAN
>
> If interface re1 (bridge0 member with wlan0) is in "active" status
> (=ethernet cable plugged to something): I don't have any problem, all is
> working great for my wireless clients connected to wlan0: They can ping
> devices in LAN0.
> But once I've unplug the ethernet cable connected to re1 (bridge member
> with wlan0) and re1 state switch to "no carrier", Wireless LAN clients are
> not able to reach LAN0.
It looks like ICMP unreach messages are generated by IP forwarding.
Probably because (for some reason) bridge0 interface prefix was removed from route table.
I'll try to reproduce that.

>
> Here is my rc.conf with simple subnetting for Adrian ;-)
>
> wlans_ath0="wlan0"
> ifconfig_wlan0="hostap channel 6"
> create_args_wlan0="wlanmode hostap"
> cloned_interfaces="bridge0"
> ifconfig_re0="inet 1.0.0.1/24"
> ifconfig_re1="up"
> ifconfig_bridge0="inet 1.1.1.1/24 addm re1 addm wlan0 up"
> gateway_enable="YES"
>
> And an example with re1 in "no carrier" status:
>
> root_at_fbsd-router:~ # ifconfig bridge0
> bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu
> 1500
>         ether 02:6b:c0:de:b8:00
>         inet 1.1.1.1 netmask 0xffffff00 broadcast 1.1.1.255
>         nd6 options=9<PERFORMNUD,IFDISABLED>
>         groups: bridge
>         id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
>         maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
>         root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
>         member: wlan0 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
>                 ifmaxaddr 0 port 5 priority 128 path cost 33333
>         member: re1 flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
>                 ifmaxaddr 0 port 2 priority 128 path cost 55
>
> root_at_fbsd-router:~ # ifconfig re1
> re1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0
> mtu 1500
>
> options=82099<RXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
>         ether 00:0d:b9:3c:ae:25
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>         media: Ethernet autoselect (none)
>         status: no carrier
>
> => from a wireless LAN client (1.1.1.2) I'm trying to ping a host on LAN0
> (1.0.0.2):
>
> root_at_fbsd-router:~ # tcpdump -pni re0
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on re0, link-type EN10MB (Ethernet), capture size 262144 bytes
> 23:38:04.466866 ARP, Request who-has 1.0.0.2 tell 1.0.0.1, length 28
> 23:38:04.467052 ARP, Reply 1.0.0.2 is-at 00:08:a2:09:c4:a2, length 46
> 23:38:04.467090 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 72, seq 1,
> length 64
> 23:38:04.467226 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 72, seq 1, length
> 64
> 23:38:04.467300 IP 1.0.0.1 > 1.0.0.2: ICMP host 1.1.1.2 unreachable, length
> 36
> 23:38:05.483053 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 72, seq 2,
> length 64
> 23:38:05.483259 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 72, seq 2, length
> 64
> 23:38:05.483318 IP 1.0.0.1 > 1.0.0.2: ICMP host 1.1.1.2 unreachable, length
> 36
> 23:38:06.387304 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 72, seq 3,
> length 64
> 23:38:06.387466 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 72, seq 3, length
> 64
> 23:38:06.387514 IP 1.0.0.1 > 1.0.0.2: ICMP host 1.1.1.2 unreachable, length
> 36
> ^C
> 11 packets captured
> 11 packets received by filter
> 0 packets dropped by kernel
> root_at_fbsd-router:~ # arp -na
> ? (1.1.1.1) at 02:6b:c0:de:b8:00 on bridge0 permanent [bridge]
> ? (1.1.1.2) at fc:64:ba:97:c0:ff on bridge0 expires in 1168 seconds [bridge]
> ? (1.0.0.1) at 00:0d:b9:3c:ae:24 on re0 permanent [ethernet]
>
> => The FreeBSD router answers "unreacheable" to the host: My wireless LAN
> client never get the ICMP reply.
>
> => Now I plug eth1 to a dummy machine (just for changing its status):
>
> root_at_fbsd-router:~ # ifconfig re1
> re1: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0
> mtu 1500
>
> options=82099<RXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE>
>         ether 00:0d:b9:3c:ae:25
>         nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
>         media: Ethernet autoselect (1000baseT <full-duplex>)
>         status: active
>
> => and I restart the same ping from the wireless LAN client:
>
> root_at_fbsd-router:~ # tcpdump -pni re0
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on re0, link-type EN10MB (Ethernet), capture size 262144 bytes
> 23:44:08.597429 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 74, seq 1,
> length 64
> 23:44:08.597660 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 74, seq 1, length
> 64
> 23:44:09.604447 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 74, seq 2,
> length 64
> 23:44:09.604683 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 74, seq 2, length
> 64
> 23:44:10.609711 IP 1.1.1.2 > 1.0.0.2: ICMP echo request, id 74, seq 3,
> length 64
> 23:44:10.609874 IP 1.0.0.2 > 1.1.1.2: ICMP echo reply, id 74, seq 3, length
> 64
>
> => It's works :-)
>
> How the status of a member of the bridge can impact the routing behavior of
> other interfaces ?
> How to fix this problem ?
>
> Thanks
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