[RP-PPPoE] PPPoE over a linux logical bridge

[Éric Bischoff]

Hi all,


There seems to be problems to run roaring penguin plugin over a bridge br0 
instead of normal Ethernet interface eth0.

See the full problem report here:
http://ubuntuforums.org/showthread.php?p=7443296

Here is the part that concerns me:

============================================================================
Same problem here. I'm trying to replace eth0 with br0 (purpose is to have br0 
= eth0 + tap0), but masqueraded local network computers can't access the 
Internet anymore.

My configuration is much simpler than the first one mentioned here but the 
problem is exactly the same.

I am running Kubuntu jaunty jackalope, and package ppp (including roaring 
penguin PPPoE plugin) is version 2.4.5.

Here is my /etc/network/interfaces:
  auto lo
  iface lo inet loopback

  auto eth0
  iface eth0 inet manual

  auto br0
  iface br0 inet static
        bridge_ports eth0
        bridge_stp off
        bridge_maxwait 0
        address 10.0.0.140
        netmask 255.0.0.0
        network 10.0.0.0
        broadcast 10.255.255.255

  auto nerim
  iface nerim inet ppp
  provider nerim
      pre-up /sbin/ifconfig br0 up # line maintained by pppoeconf

/etc/ppp/peers/nerim has been modified to use br0 instead of eth0
  noipdefault
  defaultroute
  replacedefaultroute
  hide-password
  noauth
  persist
  mtu 1492
  plugin rp-pppoe.so br0
  user "ebischoff at adslc.nerim.nerim"
  usepeerdns
  ipv6 ,

I tried to put the Ethernet card interface eth0 in promiscuous mode as 
suggested above, but it did not help.

I logged the packets coming back from the Internet and I noticed that they 
arrive on interface "br0" instead of "ppp0". Here is the normal situation 
(PPPoE over eth0) as analyzed by an iptables rules with LOG target:

Jun 12 08:21:48 ns kernel: [26325.717776] IN=ppp0 OUT=
MAC= SRC=62.4.16.99 
DST=213.41.243.33 LEN=64 TOS=0x00 PREC=0x00 TTL=61 ID=33728 DF PROTO=TCP 
SPT=80
DPT=57026 WINDOW=65535 RES=0x00 ACK SYN URGP=0

And here is the problematic situation (PPPoE over br0):

Jun 11 23:50:30 ns kernel: [22485.499333] IN=br0 OUT= PHYSIN=eth0
MAC=00:1d:60:fc:58:1d:00:e0:fc:47:10:22:88:64 SRC=212.95.66.20
DST=213.41.243.33 LEN=60 TOS=0x00 PREC=0x00 TTL=56 ID=0 DF PROTO=TCP SPT=80
DPT=56875 WINDOW=5792 RES=0x00 ACK SYN URGP=0

Notice it should be IN=ppp0 and not IN=br0. Maybe this information helps.

Is there some incompatibility between bridging and PPPoE? Any thoughts?
============================================================================

The machine connected to the ADSL modem continues working fine.

I know there was a bug in RP-PPPoE with interface names shorter than 4 
characters like "br0". But this problem has been fixed already and it is 
apparently not what is happening here.


I hope this helps.

-- 
Éric Bischoff - Bureau Cornavin
Technical writing and translations
http://www.bureau-cornavin.com
(+33) 3 88 41 91 07