[nycbug-talk] Odd log messages with OpenVPN bridge

[Tillman Hodgson]

On Thu, Feb 03, 2005 at 03:21:48PM -0500, 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)

Just out of curiousity, do the errors go away if you use tun devices
instead of tap devices in your OpenVPN config?

My thinking is as follows: Tap devices are a "raw" transport. You
generally only need them if you want to carry non-IP traffic (IPX comes
to mind). Tun devices are "IP" devices, so we can eliminate an entire
layer of the stack by using them (as well as making OpenVPN more
efficient -- less overhead per packet means more data per data).

-T


-- 
Page 5: It is impossible to learn everything about Unix. Concentrate on
what you need and what you think you will enjoy.
	- Harley Hahn, _The Unix Companion_