Not sure you are ready to scan for proxies if you have to ask this question. However, you can find a list of ranges at:

IP Address Ranges (Blocks) by Country - [IPMaster.org]

Determine a Country you wish to scan and then click on the number in the Total IPs column for the ranges for that Country.

However, before beginning any scan, type don't scan these IP ranges in Google's search engine and read all the information provided. Hopefully you are familiar with the so-called dangerous proxies and would therefore stay away from ranges that would obviously include those. Reviewing the posted proxy lists should give you indications of ranges that have been scanned with some success.

You should understand that scanning for proxies is most likely against your ISP's TOS (terms of service) contract you agreed to abide by. Some ISPs take immediate action, some don't. It'll probably depend upon how active you are with your scanning. If you simply need a handful of proxies daily, most likely this venture will not be worth the effort.

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