PPTPd: 'initial packet length 4930 outside (0 - 220)'

I got home today and was greeted by a pile of emails from logcheck, informing that pptpd was upset. Here is a snippet:

Jun 26 20:02:37 lazarus pptpd[3060]: MGR: initial packet length 4930 outside (0 - 220)
Jun 26 20:02:43 lazarus pptpd[3060]: MGR: initial packet length 4930 outside (0 - 220)
Jun 26 20:03:52 lazarus pptpd[3060]: MGR: initial packet length 4930 outside (0 - 220)
Jun 26 20:04:04 lazarus pptpd[3060]: MGR: initial packet length 22415 outside (0 - 220)

It seems to have been happening about twice a minute for the last couple of hours.

Any clues what it might be?

I've started a tcpdump, and with any luck that will turn something up...

From serverfault David Wolever

• It turns out that a bunch of BitTorrent clients in Germany got it in their heads that they might be able to handshake with my pptpd... Why they wanted to do that I can only guess, but that explains the crazy packets.

  From David Wolever

• You should re-consider if you really want to be running PPTP in 2009 as the encryption is known to be fairly weak.

  OpenVPN seems to be general choice of simple VPN options (or just using SSL with select services)

  David Wolever : Ah, that's good to know – thanks.
  From LapTop006