http://www.theregister.co.uk/content/5/21284.html [...] Because the handshake is a necessary part of normal Net traffic, malicious SYN packets are difficult to filter. You can cope with an attack by changing the number of times your machine will re-try the SYN/ACK response, but you'll also deny legitimate connections if you get too aggressive. With this difficulty in mind, TechMavens' http://www.tech-mavens.com Ross Oliver decided to benchmark several hardware solutions, all in roughly the same price range, using a homebrew kit to simulate SYN floods against them. He released his results at last week's USENIX Security Symposium in Washington. He established a baseline for his test server (Apache over Red Hat 7.1), which, when unprotected, crashed at 100 SYNs/sec. The worst performers were the Cisco PIX firewall http://www.cisco.com/warp/public/cc/pd/fw/sqfw500 and Checkpoint's Firewall-1 http://www.checkpoint.com/products/firewall-1/index.html equipped with the SYNDefender module. The Cisco kit showed no advantage whatsoever, crashing at the baseline 100 SYNs/sec. Firewall-1 showed only marginally better results, breaking down (i.e., dropping connections) at a lame 500 SYNs/sec, which can be exceeded by only two or three boxes connected by T1, cable or DSL lines. It's fair to note that while one expects at least some protection from any firewall, the Cisco kit isn't marketed for SYN flood protection as the Checkpoint kit obviously is. Netscreen's Netscreen-100 http://www.netscreen.com/products/appliances.html#ns100 fared better, breaking down after 14,000 SYNs/sec for a 28-fold performance improvement at roughly the same price. Only the Top Layer AppSafe switch http://www.toplayer.com/products/hardware/index.html exceeded the test's limits, showing no sign of stress while sustaining 22,000 SYNs/sec, the maximum Oliver could throw at it with his rig. This would work out to about one dollar per SYN during a fairly severe attack, which strikes us as rather economical protection. Of course we asked Top Layer if they had any idea where the AppSafe's performance might top out. Marketing Director Dennis Anglin told us they're currently benchmarking it (and, we'll bet, tweaking it), but haven't got any solid numbers just yet. The switch distinguishes 'normal', 'suspicious' and 'malicious' traffic according to user-defined rules, and can be configured to lock out troublesome IPs for anywhere from fifteen seconds to over a week. We look forward to learning just how much punishment it can take. If any of our readers using it have anecdotal data to pass along, we'd love to see it. ®
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