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Using IPsec and Web authentication methods for securing WLAN

This tip, which is part of a two-part series, focuses on using Web authentication methods and IPsec for securing wireless LANs.

At the Spring 2004 Information Security Decisions conference Joel Snyder, senior partner of Opus One, outlined several wireless security strategies. This tip is based on the highlights from his session.

The first part of this series exposed the myth surrounding wireless insecurity and focused on several strategies -- WEP, 802.1X and 802.11i/WPA -- for locking down WLANs. So, now that you're "ready" or more willing to consider deploying a wireless LAN, here are two more strategies to consider. The second part of this two-part series focuses on Web authentication methods and IPsec for securing a WLAN.

Web authentication
Described as "firewall-style AAA," Web authentication is the most compatible and very easy to use, according to Snyder. It is also a popular choice in environments where the burden of security is on the end user (for example, students at a university) and not the network administrator. Basically, before a user passes through the firewall either to the corporate network or the Internet, a pop-up authenticates the user with either a password or a secure ID token (the technology doesn't specify a method).


However, Web authentication isn't without its share of security shortcomings. Snyder cautioned, "[Users of Web authentication] assume the link between the user and access point is secure." It's easy for someone to steal your MAC address and take over your connection reminded Snyder. The real problem, warned Snyder, is that "It's not just that you can grab someone's MAC address, it's that there are more esoteric attacks that can be carried out." You can increase security, however, if you can make the access point aware of activity. For the most part though, Web authentication has weak security and is prone to hijacking and eavesdropping.

For more information on wireless security: 

  • May 2004 Information Security magazine: Securing Air
  • Live editorial Webcast on June 8, noon ET: New developments in wireless LAN access control

    This option offers the most robust security, according to Snyder. IPsec enables positive bi-directional authentication of the user and gateway; per-packet encryption and authentication; a high re-key rate and selector-based firewall rules.

    The drawback to IPsec is that implementation and updating are difficult. Plus, IPsec requires expensive hardware investments.

    Finally, there is an interesting feature of IPsec, Snyder added: You can either terminate the tunnel at the access point directly or back haul it to a VPN security gateway behind the access point. The second option is a good way for organizations to recycle investment in IPsec by using the same model for wireless as Internet remote-access users. If you're looking to reuse expensive hardware investments, IPsec might be a good solution to consider.

    So, which wireless security strategy is right for you? Of course, that all depends on a balance between your organization's needs, budget, resources and time. Any one of these strategies -- including WEP, 802.1X and 802.11i/WPA from part one -- can help you implement a secure wireless LAN.

    About the author
    Mia Shopis is assistant editor for You can e-mail her here at

This was last published in May 2004

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