The Bogon List - Why Some Users May Not Be Able To Reach Your Site

I discovered a very interesting problem in the last month or so in regards to something called the "Bogon list". I had never heard of the Bogon list before, but after doing some research, I discovered it is a list of reserved IP ranges not released for public use.

Now from what I read online, many network routers across the internet will by default block request to and from IP address in the Bogon lists. Why? Well apparently spammers and other bad sorts have been known to try and use IP addresses from the range for whatever reason. So as a preventative measure, routers may simply ignore requests from these IP ranges, since they are technically suppose to be reserved and not in use by the public. This also saves on router processing cycles since they can simply discard the packets and move on.

Well on to my problem. I had a few users of my site complaining to me over email that they could no longer get to my site. For weeks they had been trying with no luck. They would get a timeout or page/site not available message.

Initially I tried seeing if their ISP was blocking our site (for whatever reason), and found the ISPs were not blocking it. One ISP however tipped me off that the user in question did have an IP address that was recently released from the Bogon list. The ISP simply gave the user a new IP and they were now able to access my site.

Armed with this information I started talking to my other users who were also unable to get to my site. Surprisingly they were all using IP addresses that were recently (in the last year) released from the Bogon list.

What this tells me is the Bogon system is a broken system. If they can release IP ranges to the public, and up to a year later those IP ranges are still being blocked by routers all over the net, how is anyone suppose to know when a site is really down, or up?

I was pissed because it makes my site look like it is offline, which is bad PR and get get my site a bad reputation in Google search results when users visit my links only to find they can't get to my pages and they go back to Google and clicks some place else.

Now I realize this problem appears to be isolated to a small set of IP ranges that get release periodically, but the the problem is one that is extremely difficult to troubleshoot, and even more difficult to track down and resolve. The "problem" router that might not have their Bogon list updated could be one of a hundred in the path from your site to the user's computer.

Long story short, if you have some users that just can't get to your site and you don't have a clue why, check their IP addresses against the Bogon release lists from the past year. Your users may need to request a new IP to regain access to your site.