Network-security company Palisade Systems this week will launch software that can identify and block copyrighted songs as they are being traded online. Backed strongly by the Recording Industry Association of America, the song-filtering software has already triggered interest in Washington, D.C., along with strong scepticism in the peer-to-peer world and among some students and universities.

Palisade's new tool is the fruit of a cross-licensing deal struck early in the year, which also gave Audible Magic rights to use Palisade's network-monitoring technology to offer a similar product. Palisade executives say their university customers in particular are interested in the song-blocking capabilities.

Audible Magic's technology, the manufacturer of the software which will be released as an option in the newest version of Palisade's PacketHound network-management services, has formed the centrepiece of an ongoing debate over the future viability of peer-to-peer networks. As the filtering technology begins to appear this year inside university and other networks, the intensity of that debate is likely to grow.

For much of the early months of the year, RIAA executives helped guide Audible Magic chief executive Vance Ikezoye around Washington, D.C., offices, advocating the song-blocking technology as a tool for stopping copyright infringement on file-swapping networks. If built into file-trading programs such as Kazaa or Morpheus, it could help block large numbers of illegal trades, the record industry group said.

File-swapping companies -- some of which have contended that filtering their networks is impractical or even impossible -- said they were sceptical of the claims, noting that neither RIAA nor Audible Magic had given them a demonstration of the filtering tools. Industry trade group P2P United says it has repeatedly contacted the company asking to see the filters in action. Palisade's version of the technology sits inside a network, rather than inside a file-swapping program. If installed in a university, for example, it could look inside students' emails, instant messages and peer-to-peer transfers, seeking audio "fingerprints" that could be compared with information in Audible Magic's database.

If a match is found, it would block the transfer of the song midstream. Jacobson said the identification process would not work on an encrypted network, such as is used in several newer file-swapping programs. However, the Palisade software could also act to block those applications from using the network altogether, instead of blocking individual song transfers, he said.

Palisade's PacketHound software will be available to customers this week, the company said.