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Port Knocking

Post date: April 16, 2005, 10:04 Category: Views: 3118 Comments
Tutorial quote: Firewall administrators are challenged to balance flexibility and security when designing a comprehensive rule set. A firewall should provide protection against malfeasants, while allowing trusted users to connect. Unfortunately, it is not always possible to filter out the bad guys, because filtering on the basis of IP addresses and ports does not distinguish connecting users. Bad guys can and do come from trusted IP addresses. Open ports remain a necessary vulnerability: they allow connections to applications but also may turn into open doors for attack. This article presents a new security system, termed port knocking, in which trusted users manipulate firewall rules by transmitting information across closed ports.


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