I have a mikrotik that looks like it is continually polling to port 5678 (hex 162e).
from my next hop cisco:
Fa0/0 x.x.x.x Null 255.255.255.255 11 162E 162E 2

Now, I have firewall rules on the inbound to break it by port, but it is still doing it once every minute - it looks like something polling for a service, and is kinda annoying. Anybody seen anything like this, or have pointers on how to have the router kill it?
The entry in the Mikrotik log for this is:
Jan/11/2005 08:50:10 input->DROP, in:ether2, out:(local), prot UDP, x.x.x.x:5678->255.255.255.255:5678, len81

the x.x.x.x is the management IP of this router.

If I recall correctly these are neighbourhood discovery packets. You can disable neighbourhood discovery for all interfaces in your MikroTik router, and those packets will go away...