Kevin Hofman's popular hip-hop blog, OnSmash.com, was one of 82 sites shut down by Immigration and Customs Enforcement over Thanksgiving weekend.

Thanksgiving Day had barely begun when Kevin Hofman’s BlackBerry buzzed. It was one of the technical operators of OnSmash.com, Hofman’s popular hip-hop blog, telling him that the site had gone mysteriously blank just after midnight.

“At first I thought it was hackers,” Hofman said. But within hours a notice went up on the site saying that its domain name had been seized by the U.S. Immigration and Customs Enforcement unit of the Department of Homeland Security; it was one of dozens of sites shut down, accused of copyright infringement and selling counterfeit goods.

But Hofman, a brawny Long Islander in his early 30s who formerly worked for a major record label, does not think of himself as a pirate.

OnSmash.com and the handful of other music blogs shut down by the government post brand-new songs and videos without licenses, but much of that material is often leaked to them by managers, music labels and even the artists themselves.

As a result, these sites have a complex symbiosis with the music business. While the Recording Industry Association of America wants to shut them down, the rank and file of the record labels — particularly in hip-hop circles — uses them as marketing tools and publicity outlets.

“To Joe Q. Public, ‘leak’ sounds like a bad word,” Hofman said in an interview at a pizzeria in New York City, his lawyer by his side. “But if you’ve ever been in a marketing meeting at a record label, it’s, ‘Hey, can you leak this to the blogs?’ Leak is now a marketing verb.”

In addition to OnSmash .com, the music sites shut down included Dajaz1.com, RapGodFathers.com and rmx4u.com; another, torrent-finder.com, is a search engine for users of BitTorrent, a file-sharing system that can be used for any kind of data.

The seizures over Thanksgiving weekend — most of the 82 sites involved were shut down for selling knockoff handbags, sunglasses and other goods — were made without warning. Internet advocacy groups like the Electronic Frontier Foundation have expressed alarm at the precedent the action might set.

Victoria Espinel, the White House’s intellectual property enforcement coordinator, said on Dec. 6 that more shutdowns could be expected soon as the government pursued “pirates and counterfeiters.”

Some of the people most surprised by the shutdowns are within the music business itself.

“The industry and my artists don’t have any issues with most of these sites,” said Corey Smyth, a manager of rappers and producers like Lil Jon and Talib Kweli. “When you’re trying to get something out, this is where the kids go.”

For artists, blogs that traffic in the latest leaks are not always beneficial, nor is it always clear where a leak is coming from. Fabolous, a Brooklyn rapper on the Def Jam label who has worked with OnSmash.com, said competition among blogs had resulted in a free-for-all in which e-mail accounts for artists and producers had been hacked in search of any snippets of new music that could attract readers.

“It’s a double-edged sword,” Fabolous said. “It’s a great, great promotional tool to get whatever you’re trying to get out to the masses. But on the other side it is a little bit of piracy, because sometimes it’s not always stuff that’s given — there’s certain things that are taken.”

More than a decade since the advent of the file-sharing service Napster, the big labels are still struggling to reconcile the promise and the threat of digital music.

Immigration and Customs Enforcement has not explained how it selected sites that deal in downloadable music, but a spokesman for the Recording Industry Association of America, which represents the major music labels, said it had worked with ICE and other federal agencies in identifying infringing sites.

“The sites and services we identify are flagrantly violating federal copyright laws, illegally offering songs of well-known artists or prerelease content not commercially available online or in any store,” said the trade group spokesman, Jonathan Lamy.