Denial of Service Attack (DOS), Grrr…. by Elliott C. Back

Denial of Service Attack (DOS), Grrr….

Posted in My Blog, Spam, Performance, Hacking, WTF by Elliott Back on November 4th, 2007.

Today I had the pleasure of a random guy in Mexico recursively downloading as much of my site as he could, which sent my CPU load to 2.0, a level that Dreamhost would find acceptable but which I personally freak out about. The r-dns and IP of this guy are:

dsl-189-171-15-59.prod-infinitum.com.mx
189.171.15.59

He started at 04/Nov/2007:12:04:36 and ended (by iptables ban) at 04/Nov/2007:20:17:03. In those 8 hours and thirteen minutes, he made over 250,000 requests. That’s an extra 8.5 requests per second from a single IP, which is clearly unacceptable behavior:

[root@fc624389 ~]# cat access_log | grep 189.171.15.59 | wc -l
251923

If you don’t believe me, the next biggest offender over the last 24 hours made only 4,400 requests:

[root@fc624389 ~]# cat access_log | cut -d’ ‘ -f1 | sort -n | uniq -c | sort -nr | more
251923 189.171.15.59
4403 66.249.73.116
2012 76.88.78.239
1646 70.141.105.233

The user agent of this guy doesn’t tell *me* anything about him, but maybe one of you readers has an idea?

189.171.15.59 - - [04/Nov/2007:12:04:38 -0500] “GET /wp-content/themes/greenmarinee/images/links_bullet.gif HTTP/1.1″ 200 467 “http://celebrity-photos.elliottback.com/” “Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Media Center PC 3.0; .NET CLR 1.0.3705; .NET CLR 1.1.4322)”

Another thing that bugs me is he requested each URL about 7 times. WTF? Do you really need to spider my site as fast as you can seven times?

[root@fc624389 ~]# cat access_log | grep 189.171.15.59 | cut -d’ ‘ -f11 | sort | uniq | wc -l
35414

I am either thinking of writing a very evil script to confuse non-google/msn/live/ask/yahoo bots by writing in an infinite number of invisible links into my websites, or installing some kind of mod_throttle into my apache. It looks like mod_limitipconn might help here, too.

This entry was posted on Sunday, November 4th, 2007 at 9:43 pm and is tagged with media center pc, denial of service attack, content themes, denial of service, celebrity photos, images links, random guy, unacceptable behavior, pc 3, google, uniq, cpu load, infinitum, recursively, bullet gif, access log, seven times, infinite number, freak, f1. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback.