anyway to check if ISP is blocking ports

caykroyd · 08-30-2006, 03:27 PM

I think my ISP may be blocking port 25. Is there anyway to confirm this, without asking them? I'm afraid if I ask and they are not blocking, they may start blocking it.

acid_kewpie · 08-30-2006, 04:26 PM

you can see what somethign like Sheilds Up! says about your IP, but it depends what equipment you have, if you can put a machine in a dmz, or just portforward 25 from a router then you can tcpdump on the machine and see if you see any inbound packets on that port

blankbmx · 08-30-2006, 06:56 PM

yes, you can also set up smtp on a local machine, and telnet localhost 25. if that works, but you cannot telnet to port 25 on that box from a remote ip, then chances are your isp is blocking that port.