Why is my IP blocked at a website I visit regularly after I changed ISPs?

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Summary: IP address blocking frequently has an unintended side-effect: you could end up paying for someone else's bad behavior.

I just installed a new Express Card with Verizon Broadband wireless last night. Had tons of fun accessing the web from places I usually cannot, (we are in trucking) until I got to my favorite forum. It's a public place I have been to thousands of times, but instead of happily browsing all the daily news events and checking to see if the world blew up yet, I found myself blocked by a big white screen that said YOUR IP ADDRESS HAS BEEN BANNED. What can I do? I can't go to the forum owners to tell them it's just lil 'ol me. Besides, I have picked them up on all other wireless connections at various hotspots I run into, so what's up? Do they not like my new Verizon service?

I'm sure they like the Verizon service just fine. What's more likely is that someone else who also used the Verizon service broke a forum rule or something and that got him banned.

Unfortunately this demonstrates one of the problems with IP-based banning or identification. It frequently doesn't work. There's a good chance that you're blocked instead and the original user can get right back in.

There are roughly three things you can do.

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As you know by now every computer connected to the internet is assigned an IP address. Those addresses are assigned by your ISP, statically (a permanent assignment) or dynamically when you connect (a temporary assignment).

In the case of Verizon's wireless service, your computer is assigned a dynamic IP when you initially connect. The computer retains that IP address as long as it's connected to the network (I'll have a small caveat about that in a moment). When you disconnect that IP is returned to Verizon's available pool of IP addresses where it might be assigned to the next person to come along and connect.

In other words the IP your machine is assigned today may have been assigned to someone else before you.

So here's what's most likely happened:

• Person A comes along and connects to the internet via Verizon's broadband. They're assigned an IP address.

• They visit the forum you're also wanting to visit and they raise heck. The administrator of that forum says "enough of this", notes what IP address they're posting from, and blocks it.

• Person A disconnects.

• Some time later you come along. It could be minutes, hours, or days later, but you're randomly assigned the same IP address that Person A was using when he (or she) was causing problems.

• That IP is still blocked at your forum. You pay the price for someone else's behavior.

The ultimate irony is that Person A can probably reconnect, randomly get assigned a different IP address, and continue posting.

However, the forum moderator could deal with that irony by blocking all IP addresses which originate from Verizon's broadband. ISPs are themselves assigned blocks of IP addresses, and it's relatively easy to block an entire range.

Unfortunately there's no real way for you to know what's happening.

Here are the options as I see it:

1. Disconnect and reconnect, hoping to get a new IP address. (Run "ipconfig" in a Windows Command Prompt to see the IP address that's been assigned to your Verizon connection.) Caveat: you may want to make sure to power down the Verizon Express card and then turn it back on. It's possible that even though "disconnected" it may retain its IP address while powered on. If you get a new IP address, then you may be able to visit the forum. If you can't, chances are the entire range is blocked and you'll have to take the next step.

2. I know you said you can't just go to the forum owners, but in fact that's what you'll have to do. This isn't something that you'll be able to side-step without their help, especially if they've blocked an entire range of IP addresses.

3. Use a different ISP. As you say, you've been able to access this forum at various Wifi hotspots, and perhaps that's what you'll need to keep doing if you can't get the IP block removed. Use your Verizon connection on the road and wherever else it makes sense, but get your forum "fix" by firing up the Wifi at local hotspots along the way.

OK, there's a fourth option: use a proxy. Something like Anonymizer will route your traffic through their servers, making it look like it's coming from their IP address instead of yours. There are several such services of varying complexity, speed, and cost. I've not yet used one myself.

For the record I also recently got a Verizon Express card and have been quite happy with it. Or rather, my wife has, as she recently spent an entire 1.5 hours on the road running her business remotely while I was driving us down the freeway.

Related:

• Ask Leo! - How is my IP address assigned?

• Ask Leo! - How do I figure out who owns an IP address?

• Ask Leo! - Does seeing a different IP address mean I'm seeing a different computer?

Article 11929 | Posted October 21, 2007