The only way I know to get past it is to add an "s" after the http.
https://
Wait, how did you post this?
Post the site in Google Translate.
I'll try ultrasurf.
http://centhra.com/proxy/It's not blocked anywhere because it's my personal domain so, y'know.
Some schools will filter out proxies based on the name of the URL. An example being yours because it contains the word "proxy"
http://centhra.com/pxyhappy? I doubt they'd do that anyway, proxy is a legitimate word that has other uses than disguising network traffic.