“This unfortunately represents one of few ways law enforcement gets good inroads into this community,” said Bill Woodcock, research director at the Packet Clearing House, a nonprofit group in Berkeley, Calif., that tracks Internet traffic.

In hacker parlance, to be unmasked is to be dox’d, as in documented. And by hacker logic, to be dox’d is to be put out of business. An online alias is an essential weapon: it conceals a person’s name and whereabouts, while allowing the creation of an alternate identity.

Indeed, the handbook for new recruits to Anonymous, the global hacker collective from which Lulz Security sprang earlier this year, contains tips on safeguarding one’s identity — from how to steer clear of Web sites that track online activity to masking one’s Internet provider.

One of the tools it suggests is Tor, a network of virtual tunnels originally developed by the United States Naval Research Laboratory to protect online government communications. “In our world,” the handbook concludes, “a good defense is the best offense.”

Despite the detailed profiling by the A-Team and other hacker groups including Team Poison and Web Ninjas, no professed Lulz Security member has admitted to being dox’d, and some have merrily denied it. But the campaign seems to have had some effect.

The A-Team’s supposed outing of seven of Lulz Security’s members coincided with the group’s announcement that it was disbanding. And a spokesman for the group, using the alias Topiary, bid a public farewell in typically impish language: “Sailing off — watch your backs and follow the north wind, brazen sailors of the ’verse.”

The A-Team posting about LulzSec included mundane personal details. The sister of one purported LulzSec member, it said, was a bartender in a bowling alley in a small British town. Another member was described as “very ugly.” A third, the group railed, cannot hack at all: “He doesn’t actually do anything except give interviews.”