communicate with actual groups. offer themselves as potential terrorists. >> reporter: need proof? prosecutors say the men accused of the boston bombings used jihadi websites for inspiration and bomb building advice. security analysts say anwar al alawki exchanged e-mails with nadal hasan. and khalid shaikh mohammed is believed to have used a hotmail account. >> al qaeda started with one a decade ago. we have at least a dozen al qaeda web forums that host thousands of individuals. >> reporter: a few years back when the hunt for osama bin laden was still raging, some intelligence forces believed al qaeda was even developing its own intranet that was electronically hidden behind jihadi websites and accessible to only a few people.