Comcast blocks spam loophole

TalkBack 3 of 24:

Next »

« Previous

• Thread View
• Flat View

Doesn't affect home customers

Wow. Comcast's vast army of infected, back-doored and otherwise "owned" home PC's has been the bane of my existence for the last couple of years, and I've gone to great pains to try to block inbound access to port 25 from all known dynamic and dialup netblocks (at one point blocking all of 24.0.0.0/8, for example). Blocking those connections at their source is an answer to a long-standing prayer for this sysadmin, and the very first thing Comcast has ever done to impress me.

Comcast's home customers should be connecting to Comcast's servers to send E-mail. Typically that would be on POP3 port 110, not SMTP port 25. There is *no* legitimate reason -- none! -- why any home PC, Comcast or otherwise, should be talking to *my* servers on port 25. My networks are configured to allow only SMTP servers to connect outbound on port 25; there's no reason why ISP's shouldn't do the same.

Of course, it's possible that Comcast has some business customers who want to run their own SMTP servers. Those folks are also typically going to want static IP addresses, higher upstream bandwidth and the like, and ISP's have been making that distinction between their home and business customers for years. Charge 'em a little extra, let ARIN know which netblocks are likely to contain real SMTP servers, and we'll all take the necessary steps to open up the barriers sufficiently to let that traffic through.

Posted by: TickedOffSysAdmin   Posted on: 06/11/04 You are currently: a Guest | Members login | Terms of Use

Alert moderator to an offensive message

Subscribe to this discussion via Email or RSS

SponsoredWhite Papers, Webcasts, and Downloads

• Why Isn't Server Virtualization Saving Us More? A Few Small Changes May Dramatically Increase Your Efficiency VMware Companies have rapidly adopted server virtualization over the past few ... Download Now
• Five Steps to Determine When to Virtualize YourServers VMware Server virtualization isn't just for big companies. Entry-level ... Download Now
• Three Steps You Need to Know to Stop Data Loss Varonis Sensitive data exposed to misuse or loss... it is the stuff of nightmares ... Download Now