On blocking Chinese IP addresses
The Great Firewall of China
Comment In the 1980s, I was unbeatable in Trivial Pursuit, and to this day, I still possess a love of trivia. Here's some neat facts about the Great Wall of China. Did you know...
- The Great Wall sprawls more than 1500 miles in length.
- You can see the Great Wall from low orbit, but not from the Moon (urban legend!).
- With the materials used to build the Great Wall, you could build 120 Egyptian pyramids, or a six inch tall wall completely around the equator.
- At its peak, one of every 3 Chinese men was busy building the Great Wall.
- You know what Richard Nixon said when he was in China and was taken to the Great Wall? "I think that you would have to conclude that this is a great wall." It's true!
Recently I was thinking about China again when I heard two stories from friends that sounded eerily similar. In both cases, web servers were hacked due to a vulnerability in home-grown PHP apps, and after the inevitable (and always painful) server rebuilds, a new attention to security in totum was now observed. Unnecessary services were disabled, all scripts and third-party apps were carefully audited, and user privileges were tightened with a lug wrench. As part of the new attention to security, the admins began to pay close attention to the web server's access and error logs, and what they saw astonished them.
Their web servers were pounded constantly by requests for proxy services - and they weren't running proxies. Their web servers were asked, every few minutes, to run CGI scripts - and there weren't any CGI scripts on the machines. Requests for directory indexes came in fast and furious, and yet directory indexing was shut off. Someone was asking, over and over again, for files that didn't exist - files with really weird, suspicious names.
(I'm sure many of you are going to leave comments below saying "What idiots! How painfully obvious! Only a fool would be surprised by this stuff!" You may very well be correct in all three statements, but that still doesn't mean that many, many people do not know this stuff, and need to be educated about it.)
Even more interesting, the vast majority of these highly shady requests were coming from machines in China. The IP addresses ranged all over the map, but every time WHOIS was run on them, back came a block in China. Eventually, it seemed like every province in China was involved, as this fragmentary list shows:
- Oriental Cable Network Co., Shanghai
- China Guangdong Province Network
- China Fujian Province Network
- China Hubei Province Network
- China Beijing Province Network
- China Hangzhou Node Network
- Shanghai sichuanshengpenganxianjianyezonggongsi Co., Ltd
- China Anhui Province Network
- China United Telecommunications Corporation, Xicheng District, Beijing, China
- China Jiangmen Broadband Network
And on and on.
Both of my friends thought about their situations, and both came to the same conclusion: block the entire IP ranges! Use WHOIS to look up the IP address' range, then block 'em with the server's firewall. This quickly grew into a...