Music fans swapping songs online are fighting industry efforts to watch and police what they do.

Music downloaders are trying to hide what they are doing

In recent weeks, the US music industry has stepped up attempts to stop piracy on peer-to-peer networks such as Kazaa and Grokster.

The industry's trade body has started suing individual file swappers, has sent warning messages to millions of peer-to-peer users and is thought to be developing programs that hijack the computers of suspected pirates.

But users are fighting back by creating tools that help people avoid the attention of anti-pirate groups and block attempts to limit what they can do online.

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In late April, the RIAA used the messaging systems built in to the Kazaa and Grokster peer-to-peer file swapping systems to remind people that it is illegal to distribute copyrighted pop without permission.

Companies working on behalf of the music industry are known to watch peer-to-peer networks to find people pirating pop music and to plant fake files that look authentic but when played are recordings of white noise.

But net savvy file swappers are fighting back and creating tools that help people avoid the attentions of the piracy police as well as spot the bogus files.

Peer-to-peer news sites, such as Zeropaid, regularly provide lists of net addresses known to be used by the music industry and its proxies.

PC users could find their machines are hijacked

Net users with a personal firewall can tell the software to block these addresses so their files cannot be downloaded by people using them. This makes it much harder for the music industry to find out if a particular track being offered is pirated.

One of the most popular lists, called ZeroData Bad IP Block List, is prepared in a format for a popular firewall.

Also available is a program called PeerGuardian that was originally written to block the spyware inside some peer-to-peer programs but has been updated to block particular net addresses too.

Blocking the addresses stops users downloading files from the locations and should help them avoid fake files.

Currently, some of the net address-blocking tools are not perfect as the range of addresses they knock out can be very wide and stop some people using popular sites.

Other users are turning to the Kazaa Lite program which is a version of Kazaa with the spyware and adware stripped out. This program has tools built in that let people restrict who can see their list of files that want to share.

Online net technology magazine Security Focus was among the first to break the news about the peer-to-peer fightback.