nanog mailing list archives
Re: ISP port blocking practice
From: "Ricky Beam" <jfbeam () gmail com>
Date: Fri, 03 Sep 2010 22:30:19 -0400
On Fri, 03 Sep 2010 08:12:01 -0400, Owen DeLong <owen () delong com> wrote:
Really? So, since so many ISPs are blocking port 25, there's lots less spam hitting our networks?
Less than there could be. It appears a lot less effective because there are so many ISPs not doing any blocking. Both of my residential connections are open, and always have been. (even dialup was unblocked. which I always found odd since the UUNET wholesale dialup agreement requires the RADIUS response contain a packet filter limiting port 25 to your mail server(s).)
If I block port 25 on my network, no spam will originate from it. (probablly) The spammers will move on to a network that doesn't block their crap. As long as there are such open networks, spam will be rampant. If, overnight, every network filtered port 25, spam would all but disappear. But spam would not completely disappear -- it would just be coming from known mailservers :-) thus enters outbound scanning and the frustrated user complaints from poorly tuned systems...
--Ricky
Current thread:
- Re: ISP port blocking practice, (continued)
- Re: ISP port blocking practice Owen DeLong (Sep 03)
- Re: ISP port blocking practice John R. Levine (Sep 03)
- RE: ISP port blocking practice Paul Stewart (Sep 03)
- Re: ISP port blocking practice Doug Barton (Sep 03)
- Re: ISP port blocking practice Franck Martin (Sep 03)
- Re: ISP port blocking practice Owen DeLong (Sep 03)
- Re: ISP port blocking practice John R. Levine (Sep 03)
- Re: ISP port blocking practice Robert E. Seastrom (Sep 08)
- RE: ISP port blocking practice Brian Johnson (Sep 12)
- Re: ISP port blocking practice Patrick W. Gilmore (Sep 03)
- Re: ISP port blocking practice Ricky Beam (Sep 03)
- Message not available
- Re: ISP port blocking practice Patrick W. Gilmore (Sep 03)
- Re: ISP port blocking practice Claudio Lapidus (Sep 05)
- Re: ISP port blocking practice Patrick W. Gilmore (Sep 05)
- Re: ISP port blocking practice Franck Martin (Sep 05)
- Re: ISP port blocking practice Paul Ferguson (Sep 05)
- Re: ISP port blocking practice Jon Lewis (Sep 05)
- Re: ISP port blocking practice Owen DeLong (Sep 05)
- Re: ISP port blocking practice Franck Martin (Sep 05)
- Re: ISP port blocking practice Jon Auer (Sep 06)
- Re: ISP port blocking practice Scott Howard (Sep 11)