Federal authorities aren’t looking to prosecute them, but to pay them to secure the nation’s networks. General Dynamics Information Technology put out an ad last month on behalf of the Homeland Security Department seeking someone who could “think like the bad guy.” Applicants, it said, must understand hackers’ tools and tactics and be able to analyze Internet traffic and identify vulnerabilities in the federal systems. Defense Secretary Robert Gates said the Pentagon will increase the number of cyberexperts it can train each year from 80 to 250 by 2011.