PPTP Dial on Demand - Starting Unexpectedly

RouterOS General
1

I was playing around with my RB2011 tonight and thought I would create a PPTP client connection to another RB2011 I have deployed at another site.

Got the PPP interface configured, set as dial on demand, got routing squared away, NAT enabled, Mangle rule added for a single remote subnet, and everything came up.

Played around with it a bit then decided to wait out the idle timeout that I had set to 10 minutes. Put the laptop into sleep mode and waited to get the notification on my phone that the ppp session had ended, but it never came. Waited about 40 minutes and decided to hop back on the laptop to see what’s going on.

Used Torch to see what traffic was going across the PPTP link. It was broadcast traffic, src=255.255.255.255 dst=0.0.0.0 keeping the tunnel connected. I tried setting the session timeout to 1 minute while playing with different settings. At 1 minute, the tunnel connects and disconnects after 1 minute like it should but then I get the random broadcast traffic and the tunnel comes back up.

Any ideas to keep that broadcast traffic from bringing up the dial on demand tunnel?

2

Drop it by firewall rule.

3

I tried that but must have done something wrong with rule creation.

What should the rule look like?

I did chain=forward src=255.255.255.255 out int=pptp interface action=drop

4

So Wireshark pointed me to the culprit tonight… it was MikroTik discovery protocol probing the PPTP client interface.

So far everything is looking good after disabling discovery protocol on that interface.