As network protocols are becoming even more stealthy at every new release, spotlights are on network filtering solutions and their ability to filter unwanted flows. In particular, ISPs and corporate IT managers are urging solutions providers to provide them with ways to contain Skype and P2P traffic. While the reason behind Skype blocking remains mainly commercial, other concerns often come into consideration:

Many businesses and governmental agencies are required by law to log, archive, and produce reports on all electronic messages. Since, again, Skype is strongly encrypted—essentially undecipherable—there's no way that conversations or message threads carried on using it can be compliant with such regulation.

But even where legal mandates are not an issue, organizations are understandably reluctant to have their employees communicating outside the enterprise using facilities over which they have no control whatsoever. File transfers using Skype, for example, cannot be detected.

Morganti told VoIPplanet.com that their Skype Asynchronous Filter was an extremely simple software. "It recognizes Skype or other P2P flows". "The policy enforcement is likewise simple; you can do anything, from blocking SkypeOut and allowing Skype2Skype and SkypeChat, to allowing little bandwidth to overall Skype traffic. " he said.

These policy options let a company, for example, opt to allow the use of Skype by international employees and branch offices, while blocking it for finance, marketing and manufacturing departments. In other words, keeping its use confined to instances in which there is some rationale for that use. Alternatively, they can block it altogether.

The Skype Asynchronous Filter provides further insight by logging and reporting on inbound and outbound Skype traffic, and flagging blocked attempts at its unauthorized use, so the IT department has an accurate idea of how much activity there is, and can verify that policies are in fact being enforced.

According to Dominique Morganti, the idea for Skype Asynchronous Filter really came from Lynanda customers: "We had customers evaluating the Skype filter who told us—when they heard that it detected Skype—' What I really need is just a very transparent software, opensource, easy to configure, easy to deploy, that can detect Skype and other unwanted P2P traffic.' Every IT manager we were talking to was telling me the exact same thing, that they want total control over their network and the filtering system they use, so it made me say to myself, 'Well, maybe it's time to release this software to the masses'. And that's precisely what we did."

The system is reported to be used successfully by the chinese local ISP, China Telecom. Skype will be blocked in Shenzhen, Shanghai, Beijing and Guangzhou using this filter, a blockade for commercial reasons, as China has not released VoIP licenses yet. According to the Financial Times, Wang Leilei, the head of the Hong Kong-based Internet provider Tom Online, confirmed that China would not be issuing any voice over Internet protocol licenses until 2008. The press report for China block with the asynchronous filter is there http://tech.sina.com.cn/i/2005-09-08/0239714544.shtml .

The ability to provide an universal software able to detect and filter Skype and P2P traffic, independently of the software version, was critical for businesses and ISPs. The release of this software under an opensource licensing scheme will undoubtly open a new window in the traffic management scene.