It is quite easy to block a complete ip range. I have done it many times.

Normally you would add an ip address to the banned or blocked list by entering the full ip address eg: 183.61.14.74

To block a complete range from, for example an particular isp in china you enter the ip address in your blocked list as follows 183.61.* or 183.61.*.*

This will block all ip addresses starting with 183.61.

While your at it, it might pay to block this range as well, 14.17.*.*

Cheers Ric