[nycbug-talk] Odd log messages with OpenVPN bridge

[Jonathan]

Isaac Levy wrote:
> On Feb 3, 2005, at 3:21 PM, Jonathan wrote:
> 
>> I keep getting the following messages in my daily security run and 
>> clearly they have something to do with network looping but I don't 
>> know what causes them or how to look into them further.  I did try but 
>> Google turned up nothing at all :P
>>
>> server.kc8onw.net kernel log messages:
>>
>> >> -- loop (0) 00.40.05.49.45.12 to rl0 from tap0 (active)
>> >> -- loop (1) 00.40.05.49.45.12 to tap0 from rl0 (active)
>> >> -- loop (2) 00.40.05.49.45.12 to rl0 from tap0 (active)
>> >> -- loop (3) 00.40.05.49.45.12 to tap0 from rl0 (active)
>> >> -- loop (4) 00.40.05.49.45.12 to rl0 from tap0 (active)
>> >> -- loop (5) 00.40.05.49.45.12 to tap0 from rl0 (active)
>> >> -- loop (6) 00.40.05.49.45.12 to rl0 from tap0 (active)
>> >> -- loop (7) 00.40.05.49.45.12 to tap0 from rl0 (active)
>> >> -- loop (8) 00.40.05.49.45.12 to rl0 from tap0 (active)
>> >> -- loop (9) 00.40.05.49.45.12 to tap0 from rl0 (active)
>> >> -- loop (10) 00.40.05.49.45.12 to rl0 from tap0 (active)
> 
> 
> Woah.  Creepy.  Wish I had a clue on this one- very interesting.
> 
> What OS are you running here?  What devices are tap0 and rl0?
> 

rl0 is the NAT'ed local network interface, dc0 is just an extra card 
right now, tap0 is

(from the man page)
The tap interface is a software loopback mechanism that can be loosely 
described as the network interface analog of the pty(4), that is, tap 
does for network interfaces what the pty driver does for terminals

In this case tap0 is being used by openvpn (http://openvpn.net/) to 
transparently bridge two networks at the MAC layer so rl0 and tap0 are 
bridged.  My main reason for this is to play games that rely on UDP 
broadcasts, that and just to learn more stuff :)

uname -a:

FreeBSD server.kc8onw.net 5.3-RELEASE FreeBSD 5.3-RELEASE #0: Sun Nov 14 
19:38:43 EST 2004 
root at server.kc8onw.net:/usr/obj/usr/src/sys/GENERIC  i386

ifconfig:

dc0: flags=108802<BROADCAST,SIMPLEX,MULTICAST> mtu 1500
         options=8<VLAN_MTU>
         ether 00:04:5a:50:27:e0
         media: Ethernet autoselect (none)
         status: no carrier
rl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
         options=8<VLAN_MTU>
         inet 10.70.2.2 netmask 0xffffff00 broadcast 10.70.2.255
         inet6 fe80::200:21ff:fefa:30cd%rl0 prefixlen 64 scopeid 0x2
         ether 00:00:21:fa:30:cd
         media: Ethernet autoselect (100baseTX <full-duplex>)
         status: active
plip0: flags=108810<POINTOPOINT,SIMPLEX,MULTICAST> mtu 1500
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
         inet 127.0.0.1 netmask 0xff000000
         inet6 ::1 prefixlen 128
         inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4
tap0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
         inet6 fe80::2bd:6fff:fed3:2b00%tap0 prefixlen 64 scopeid 0x5
         ether 00:bd:6f:d3:2b:00
         Opened by PID 51395

I really don't know what other information to give at this point

Jonathan