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...: Marsh Chatter

Dynamic IP Address Issue

A few weeks ago, emails sent from my home started being denied or trapped "at the gate" of the place I work. It was very odd. With emails from my home being blocked - it made it hard for me to pass along stuff that I find as I wander the Internet - at home, to my work address. Of course, having emails from my wife blocked doesn't look good either, so - it was time for some investigation.

My employer uses Barracuda products to scan & trap junk mail and the techs have been doing a lot of work with it over the last month, or so, to keep its success rate high. It works great, because my work email receives little to no junk mail in a normal day. Mind you, I'm not one to post my work email everywhere, so that helps - but I believe the low pass rate is due to the effort of the team.

So why all of a sudden was I getting "trapped".

The returned error noted it was Barracuda that blocked the mail. It also included a URL which led to a page which described that mail from my IP address was being blocked as it was designated or reported as one which emits significant junk mail. Whoa!

As there are only two of us using this system at home and our Sent Items in Outlook only showed items we sent - I immediately checked my system for bots or a virus, and such, thinking maybe some "magic" was happening on my system which caused a report like that.

As I manage a few websites, which I POP3 email to/from - I checked those and also changed their passwords, just to be sure.

Still no joy.

After reading the error page again and trying to decipher the steps needed to "get me off the Barracuda block list" - it hit me.

I do not use or pay for a Static IP Address at home - as it doubles the cost of service. This means that my ISP provides a dynamic IP address for me to access the Internet. This means that at any given point in time that address can change.

A dynamic IP address is sometimes called a "leased IP" - which might make it more understandable, as so many people lease cars. The term means that after some time - you give it back. In the case of a DSL modem, the IP address usually changes after it is power cycled - aka Off, for a period of time. This helps the ISP, as IP Addresses can be shared and they don't have to own an enormous block of IP addresses all of the time.

Well - my router is on its own power source, so it is never shutdown, well almost never. I usually only shut it down if we will be gone for extended periods of time (e.g. a full weekend or longer). Therein lies the wake-up-call and the solution...

We were gone for a full weekend visiting family, so I shut everything down and unplugged the UPS and other strips. This of course caused the router to be offline long enough for the ISP to flag us for a new IP Address when we re-connected. Insert proverbial V-8 Moment here!!

Yes, that's right! The new IP Address that we got was courtesy of someone else who practiced unsafe computing using that IP address... thank you veddy much - you idiot.

The Fix

Turn off the router for about 30-60 minutes. Restart it and like magic, we had a fresh IP Address. Send some mail and bingo - mail received properly.

Moral of the Story

Dynamic IP Addresses are the norm for ISP services from a big phone company or a big cable company - so don't think you are protected by using one or the other. Buying a static IP and practicing safe computing with that IP is the only way you can limit your risk here - however, it comes with a significant cost - enough that most general use home internet buyers will never pay.

Note to Barracuda or other White/Black List Providers

Because of the prevalence of Dynamic IP - IP Addresses "suck" as a blocking method. Just because you block an IP - doesn't mean you're blocking the offender... This is as bad as law enforcement limiting access to a road during the day, because that road is used by drunks at 2 AM bar closing. Just dumb!