我在自己的服务器上使用 nginx，几天前我注意到我的 access.log 中有一些奇怪的请求：
77.50.217.37 - - [19/Aug/2011:17:50:50 +0200] "GET http://images.google.com/ HTTP/1.1" 200 151 "-" "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; WOW64; .NET CLR 1.1.4322; Media Center PC 5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; .NET4.0E)"
174.142.123.42 - - [19/Aug/2011:17:51:59 +0200] "GET http://l08.member.ird.yahoo.com/?.src=ym&login=_420_club_chick_&passwd=112211 HTTP/1.0" 200 151 "-" "MobileRunner-J2ME"
65.52.227.217 - - [19/Aug/2011:17:52:30 +0200] "GET http://javaddiction.biz/index.php HTTP/1.1" 404 570 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)"
188.72.199.25 - - [19/Aug/2011:17:52:35 +0200] "CONNECT google.com:80 HTTP/1.1" 400 172 "-" "-" …我有这样的 httpd 日志信息，这些信息会一直持续下去。首先，这是否意味着我有病毒？我的服务器是僵尸网络的一部分吗？我的服务器是 Linux Centos 5。
tail -f /var/log/httpd/access_log
另外我怎样才能阻止这种攻击？
如何确保我的服务器没有发出请求？
我可以添加哪些其他安全措施？
69.164.209.127 - - [14/Jun/2012:18:49:05 +0800] "GET http://69.164.209.127/82d8e94797c2079b53bb3d36157a699f HTTP/1.1" 404 309 "-" "Avant Browser - MSIE 7 (Win XP)|Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Avant Browser; Avant Browser; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30)"
176.227.198.140 - - [14/Jun/2012:18:49:05 +0800] "GET http://www.google.com/search?as_q=monochrom+inurl:%3Fp%3D%2A%26option%3Dcom%5Fwordpress%26Itemid%3D%2A&num=100&hl=en&output=ie&filter=0 HTTP/1.0" 404 283 "http://www.google.com/search?as_q=monochrom+inurl:%3Fp%3D%2A%26option%3Dcom%5Fwordpress%26Itemid%3D%2A&num=100&hl=en&output=ie&filter=0" "Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 6.0)"
173.236.110.243 - - [14/Jun/2012:18:49:06 +0800] "CONNECT …