nanog mailing list archives
Re: ISP port blocking practice
From: Justin Shore <justin () justinshore com>
Date: Thu, 22 Oct 2009 20:29:27 -0500
Lyndon Nerenberg (VE6BBM/VE7TFX) wrote:
Few companies use the MSP port (tcp/587).Can you elaborate. Is this based on analysis you've conducted on your own network? And if so, is the data (anonymized) available for the rest of us to look at? My experience is that port 587 isn't used because ISPs block it out-of-hand. Or in the case of Rogers in (at least) Vancouver, hijack it with a proxy that filters out the AUTH parts of the EHLO response, making the whole point of using the submission service ... pointless.
I can't speak for Rogers but I have analyzed our netflow captures on a semi-regular basis for several things before flushing it, use of the MSP port being one of them. I've never seen any MSP port traffic on my SP network that didn't fall into 1 of 2 categories:
1) inbound scanning for MTAs listening on the MSP port, or2) my own MSP traffic or that of family members traffic running across my SP network that happen to use one of my personal servers for their own email hosting.
I can also speak from experience from the enterprise customers of the consulting side of my SP that I worked with before returning to the SP. Not a one of them made use of the MSP port. The vast majority, I'm sorry to say, used Microsoft Exchange which to the best of my knowledge doesn't support RFC2476. I did a little Googling just now and couldn't find any hits to say they did either. Some utilized RPC-over-HTTP. Most at the time didn't, requiring direct SMTP access or VPN.
I wish more people would use it though. My users wouldn't have cause to get so upset when I tell them that they have to pay monthly for a static IP to use tcp/25. It would reduce my hassles a wee bit.
Justin
Current thread:
- Re: ISP port blocking practice, (continued)
- Re: ISP port blocking practice Antonio Querubin (Oct 22)
- Re: ISP port blocking practice Valdis . Kletnieks (Oct 22)
- Re: ISP port blocking practice Ricky Beam (Oct 22)
- Re: ISP port blocking practice Justin Shore (Oct 22)
- Re: ISP port blocking practice Lyndon Nerenberg (VE6BBM/VE7TFX) (Oct 22)
- Re: ISP port blocking practice Sean Donelan (Oct 22)
- Re: ISP port blocking practice Joe Maimon (Oct 22)
- Re: ISP port blocking practice Steve Bertrand (Oct 22)
- Re: ISP port blocking practice Lyndon Nerenberg (VE6BBM/VE7TFX) (Oct 23)
- Re: ISP port blocking practice Chris Boyd (Oct 23)
- Re: ISP port blocking practice Lyndon Nerenberg (VE6BBM/VE7TFX) (Oct 22)
- Re: ISP port blocking practice Justin Shore (Oct 22)
- Re: ISP port blocking practice Joe Maimon (Oct 22)
- Re: ISP port blocking practice Justin Shore (Oct 22)
- Re: ISP port blocking practice Scott Howard (Oct 22)
- Re: ISP port blocking practice Owen DeLong (Oct 22)
- Re: ISP port blocking practice Chris Boyd (Oct 23)
- Re: ISP port blocking practice Jack Bates (Oct 23)
- Re: ISP port blocking practice Steve Bertrand (Oct 23)
- Re: ISP port blocking practice Michael Peddemors (Oct 23)
- Re: ISP port blocking practice Steve Bertrand (Oct 23)
- Re: ISP port blocking practice JC Dill (Oct 24)