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Re: What do you want your ISP to block today?
On Wed, 3 Sep 2003, Johannes Ullrich wrote: > I just summarized my thoughts on this topic here: > http://www.sans.org/rr/special/isp_blocking.php > > Overall: I think there are some ports (135, 137, 139, 445), > a consumer ISP should block as close to the customer as > they can. If ISPs had blocked port 119, Sobig could not have been distributed via USENET. Perhaps unbelievably to people on this mailing list, many people legitimately use 135, 137, 139 and 445 over the open Internet everyday. Which protocols do you think are used more on today's Internet? SSH or NETBIOS? Some businesses have create an entire industry of outsourcing Exchange service which need all their customers to be able to use those ports. http://www.mailstreet.net/MS/urgent.asp http://dmoz.org/Computers/Software/Groupware/Microsoft_Exchange/ If done properly, those ports are no more or less "dangerous" than any other 16-bit port number used for TCP or UDP protocol headers. But we need to be careful not to make the mistake that just because we don't use those ports that the protocols aren't useful to other people.