Santrex was a web hosting provider that specialised in bulletproof hosting, hosting many cybercrime forums. The service was registered in the Seychelles and once hosted the Darkode hacking forums as well as the Italian Hacking Team security organisation's control server for the Carabinieri.
At one point in the top three malicious hosts according to Google's Safe Browsing program for hosting malware, the site closed in October 2013 after failing to pay its bills to its London based data centre provider. Following this closure, Hacking Team resorted to BGP hijacking to recover control of its command and control servers.
References
Santrex Wikipedia(Text) CC BY-SA