Independent IT security testing company NSS Labs evaluated six network firewalls. Three of the six failed to stay operational when subjected to stability tests. Five out of six didn’t handle what is known as the “Sneak ACK attack,” that would enable attackers to side-step the firewall itself. The performance claims presented in the vendor’s data sheets “are generally grossly overstated,” the company says. An attacker can disrupt communications by sending certain sequences of content to a firewall’s external interface, causing it to crash.”]