Just so you know what a carpet-soiling, leg-humping snippy little lapdog the FBI's Carnivore really is, firewall outfit Network Ice has hacked out a bit of C source code called 'Altivore', enabling anyone to cobble up an e-mail sniffer with virtually the same underwhelming capabilities and based on the same principles.

The company's Altivore intro page, with links to the C file and a Carnivore anti-FUD FAQ, is posted here. The file altivore.c is ready for compiling and debugging, and is chock full of explanatory notes, several of which we found quite entertaining.

Altivore's stated purpose is to highlight several misconceptions floated by the mainstream press, such as the claim that Carnivore can't avoid capturing e-mail content. It can capture it, but it can also avoid capturing it when a content wiretap is not authorised, the company demonstrates.

Another aim is to show how poorly-written a Carnivore-like progie can be. "We believe that Carnivore has made the same technology shortcuts as our competitors in the area of reassembly, protocol analysis, and dropped packets. The Altivore source code highlights these deficiencies," the company notes.

But Altivore actually works (well, sort of; it's sorely in need of peer-review and debugging), and the company hopes it will have a few long-range effects, one of which could be to "kick the FBI off the ISP networks," Network ICE co-founder and CTO Rob Graham told The Register.

"From the FBI's perspective, it's good to be as secretive as possible," Graham noted. "Their use of commercial code [in Carnivore] goes to the Freedom of Information Act" which would prohibit them from making trade secrets public. By shipping an open-source product, Network Ice "wanted to 'out' the FBI," Graham chuckled.

And this could become more than just a laugh at the FBI's expense. The company sees a market for a product like Altivore, which could enable an ISP to comply with surveillance court orders without the FBI getting involved. One ISP could compete with another for customer loyalty by making a point of supplying the FBI with only that data which a court has authorised it to receive. And if one ISP does its own pre-filtering, and another lets the FBI do it for themselves, "which one would you prefer?" Graham asks rhetorically.

The industry overall resists getting involved with law enforcement, and greatly prefers to feed whole data streams to the Feds, so they can negotiate the civil-rights pitfalls and pay for their own screw-ups. But the possibility of adding value to their service with an Altivore-like system might make it worthwhile for an ISP to venture into the legal quagmire.

Network Ice is considering the release of a fully-supported Altivore product if interest in altivore.c should grow to sustain such a project, Graham told us. He reckoned that a six-month trial period with the unsupported code would be enough to decide whether or not to take it further. Such a product could potentially be incorporated into the company's gigabit network card developed with Intel, Graham said.

There is even an eGroups mail forum through which developers can trade tips and files and ask for help while stuffing around with the source code. ®