服务器收到大量的非法请求包

这是error.log的内容

[Mon Feb 14 07:05:24 2011] [error] [client 204.45.192.169] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:24 2011] [error] [client 217.132.113.80] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:27 2011] [error] [client 95.25.123.145] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:29 2011] [error] [client 178.120.5.227] script '/var/www/engine.php' not found or unable to stat, referer: http://obd-ii.ru/engine.php
[Mon Feb 14 07:05:36 2011] [error] [client 91.217.90.39] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:36 2011] [error] [client 195.162.68.15] File does not exist: /var/www/proxy, referer: http://botmasternet.com/proxy/http/engine.php
[Mon Feb 14 07:05:37 2011] [error] [client 77.188.93.211] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:38 2011] [error] [client 188.114.56.241] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:40 2011] [error] [client 109.230.217.191] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php
[Mon Feb 14 07:05:42 2011] [error] [client 178.77.66.56] File does not exist: /var/www/proxy, referer: http://botmasterlabs.net/proxy/http/engine.php

有谁知道是怎么回事吗？谢谢先。