nanog mailing list archives
Re: ISP port blocking practice
From: Owen DeLong <owen () delong com>
Date: Sat, 4 Sep 2010 09:50:25 +0930
Sent from my iPad On Sep 4, 2010, at 7:49 AM, "John R. Levine" <johnl () iecc com> wrote:
It's been extremely effective in blocking spam sent by spambots on large ISPs. It's not a magic anti-spam bullet. (If you know one, please let us know.)That simply hasn't been my experience. I still get lots of spam from booted hosts in large provider networks, and yes, that includes many that block 25. As near as I can tell, 25 blocking is not affecting spammers at all, just legitimate users.I know people at large ISPs with actual data. Port 25 blocking is quite effective.
Does the data show that blocking was effective, as in the host didn't detect the block and proceed around it, or, merely that lots of hosts try the direct approach first? Merely tripping over the filter, even repeatedly does not in and of itself prove efficacy. Owen
R's, John
Current thread:
- Re: ISP port blocking practice, (continued)
- Re: ISP port blocking practice Kevin Oberman (Sep 04)
- Re: ISP port blocking practice Owen DeLong (Sep 03)
- Re: ISP port blocking practice Butch Evans (Sep 03)
- Re: ISP port blocking practice Owen DeLong (Sep 03)
- Re: ISP port blocking practice John Levine (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 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)