Firewall getting hammered by Chinese

I think that server is infected or some users in that IP range are infected.
Infected computer is very common in China since many people do not care about the security(or even don't know what security software/computer virus/trojan/malware is).
And also,the quality of network administrators is quite poor.
You can use ProtoWall(Freeware) to block that IP range if you think you are bored by the firewall alerts
http://www.bluetack.co.uk/index.php