Sounds dodgy, are proxies legal?
This is a rather touchy subject, most free countries have no laws against using proxies aslong as you don’t have to bypass any security to use it. This means, if the proxy requires a username and password to access it then unless the proxy owner has given it to you, you are not legally allowed to use it. Thankfully, Black Hat SEO techniques do not include illegal activities, but if one were to step over that border then a proxy is a must.