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Jay864

join:2013-07-18
Reviews:
·Comcast

1 recommendation

Constant probes on UDP port 68 from comcast

Howdy,

Every minute and sometimes more than once a minute i get probes from a Comcast IP address that tries to connect to "255.255.255.255:68" and the ZyWALL USG20 drops them. From what I've red Comcast's DHCP service hands out IP's over this port but I already have an IP and am not asking for a new one (as far as I know). Comcast's website shows that they block this port as it is vulnerable to malicious attacks, if it's blocked why do i get probed on it every minute? (»customer.comcast.com/help-and-su···d-ports/)

The reason I put this in the ZyXEL forum is to see if this may be a configuration issue with the ZyWALL. Maybe it's configured wrong and asking for a new IP every minute? The ZyWALL is set to be the DHCP server for my network but this should not affect the WAN.

Any help appreciated.

polarisdb

join:2004-07-12
USA

1 recommendation

I get those from Comcast too on my USG 50. A couple of years ago I created a firewall rule to block it without logging to help cleanup my logfile a bit and I haven't thought about it since.

JPedroT

join:2005-02-18
kudos:1

1 recommendation

reply to Jay864
I assume you are on cable? If so, then its a reply from the DHCP server to a DHCP client. But since its destination is a broadcast address everybody on the same cable segment gets it. Even though its one of your neighbours that requested it, you still get to see the answer.
--
"Perl is executable line noise, Python is executable pseudo-code."