这是什么攻击行为？如何低档呢？

环球80天

察看mail日志，发现从凌晨5点多，一直到现在有个ip地址一直在连接我的qmail服务器，一秒钟一次，一直没有停止。 \r\n\r\n日志中全是连续的这样的纪录： \r\nJun 20 05:27:09 host splogger: 1087680429.045559 tcpserver: status: 1/100 \r\nJun 20 05:27:09 host splogger: 1087680429.046635 tcpserver: pid 89765 from 210.221.55.39 \r\nJun 20 05:27:09 host splogger: 1087680429.051056 tcpserver: ok 89765 myserver.com:61.155.158.126:25 :210.221.55.39::3381 \r\nJun 20 05:27:11 host splogger: 1087680431.263895 tcpserver: end 89765 status 256 \r\nJun 20 05:27:11 host splogger: 1087680431.264620 tcpserver: status: 0/100 \r\nJun 20 05:27:12 host splogger: 1087680432.608296 tcpserver: status: 1/100 \r\nJun 20 05:27:12 host splogger: 1087680432.609361 tcpserver: pid 89776 from 210.221.55.39 \r\nJun 20 05:27:12 host splogger: 1087680432.613806 tcpserver: ok 89776 myserver.com:61.155.158.126:25 :210.221.55.39::3397 \r\nJun 20 05:27:14 host splogger: 1087680434.823419 tcpserver: end 89776 status 256 \r\nJun 20 05:27:14 host splogger: 1087680434.824294 tcpserver: status: 0/100 \r\nJun 20 05:27:16 host splogger: 1087680436.171915 tcpserver: status: 1/100 \r\nJun 20 05:27:16 host splogger: 1087680436.253380 tcpserver: pid 89782 from 210.221.55.39 \r\nJun 20 05:27:16 host splogger: 1087680436.258694 tcpserver: ok 89782 myserver.com:61.155.158.126:25 :210.221.55.39::3424 \r\n\r\n请问，这是什么攻击行为？该如何制止呢？

phcool

在防火墙或者路由器上做限制呢

南阳岩冰

如果不是邮件病毒，就是那种针对邮件服务器攻击的DOS。