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There is a private forum site that I have accessed without issue for a long time. As of about 2 weeks ago, without warning, I suddenly cannot access the site through any browser.

My first assumption was that the site was simply taken down. Out of curiosity, a few days ago I accessed a proxy avoidance server and typed in the site's address. It loaded the page without error.

So my second assumption was that the forum administrator was blocking me. Using the proxy, I was able to log in using my name and password, no problem, which halfway disproved this second theory as I would imagine they would have deleted my account in that case.

I posted on a help board within the forum, asking if I had been punished or banned from the boards. I received a response from the administrator that no such thing had happened and he couldn't explain what was going on.

Now my last guess is that it is ISP-related. I am with Comcast (not by choice), and have been for 2 years. Over the last 2 years I've accessed the site without any problems. Suddenly it is blocked.

I thought about changing some settings in the wireless router or cable modem through which I connect, but I wouldn't know what to change or how. Would this even help?

What/Who else would be able to block my access to a particular website?

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Can you ping the site? Via name, and/or via IP? – Dmatig Mar 3 '10 at 7:20
Yes I tried pinging the site. I'm not very well versed in how the IP addresses are routed and all that but I ran through some directions online. I found that when I pinged the site on one of those ping service websites, it gave the same IP results as when I pinged from my own cmd prompt. Did I state that correctly or does it answer your question? – NoCatharsis Mar 3 '10 at 13:25
I was wondering if it was a DNS issue, for example is you pinged the ip address and it worked, but pinging the actual address and it didn't work, that suggests an issue with DNS. However, since in another answer you state you tried Google DNS, it seems unlikely that is the issue (It could be technically, but it's unlikely) – Dmatig Mar 4 '10 at 16:45
up vote 7 down vote accepted

Bunch of things to check.

  1. Maybe someone else's IP address was blocked and then transferred to you by your ISP (this can easily happen with non static IP addresses - used by residential cable service) and now your account isn't blocked but the IP address your using, is. (Most likely.) Look at the fourth paragraph here.

  2. You have some sort of security filter (browser add-on, security suite, etc.) that is blocking the site (maybe due to a false positive hit on the website, maybe they were hacked and the website is serving up malware without even knowing it). (Less likely.)

  3. Your ISP could theoretically be blocking it for much the same reasons as number two. (Not very likely.)

Hope this helps you!

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It's the ISP. (2 more to go) – Josh K Mar 3 '10 at 7:02
So if it's most likely #1, how do I verify and how do I fix? Thanks for the info. – NoCatharsis Mar 3 '10 at 13:25
1. Ask the webmaster of the site if he is blocking your IP address or a range of IP adresses of which yours is part of. 2. Ask your ISP to change your IP adress. Hopefully to an entirely different range. If those help then you have solved the issue. – ssvarc Mar 3 '10 at 16:09

feels like a dns issue to me. switch to the google public dns, reboot your computer and try to visit the site.

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Although this is awesome and has sped up my connection, it does not solve my problem. You get an up vote anyway. – NoCatharsis Mar 3 '10 at 23:50

I ran into the same problem. A friend called me in because she couldn't access a site that she'd been accessing for some time and all of a sudden she couldn't. In my case it wasn't the ISP since I could access the site without problems and I use the same ISP - Same setup. (verizon)

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