I was just notified by my ISP (thanks AT&T) that my router was listening on port 137. Uh oh! So I checked my router and sure enough I had inadvertently had the thing forwarding that port to my fileserver, which is running FreeBSD 10 and Samba. Router is running DD-WRT but there are no machines in DMZ. I've been checking network usage, and it's not different than normal. Anything I should be worried about and/or check?