The Violence Protection Center, a gun-control advocacy group, is back online after having its Web site defaced and address stolen by a pro-gun hacker. The group had not been able to receive email or modify its site from Sunday until late yesterday. The address also redirected people to a page containing obscenities and pro-gun slogans. While hijacked, a colleague sent an email to which the hacker responded. Information in the email pointed to the University of Nebraska at Lincoln.