The Generalized TTL Security Mechanism (GTSM) is a proposed Internet data transfer security method relying on a packet's Time to Live (IPv4) or Hop limit (IPv6) thus to protect a protocol stack from an attack of packets sent in rapid succession.
Contents
Set the Access Control List (ACL) to allow packets of the given protocol to only pass to the route processor (RP). The TTL must be set to either 255 if the destination is directly connect or 255 minus the range of acceptable hops if not connect directly. This method assumes however that the ACL designated by the receive path is configured to control packets passing to the RP.
Introduction
The desired purpose of this proposal is to protect router infrastructure from overload-based attacks.
Implementation
For protocols which GTSM is enabled, the following procedure is performed.
Set the Access Control List (ACL) to allow packets of the given protocol to only pass to the route processor (RP). The TTL must be set to either 255 if the destination is directly connect or 255 minus the range of acceptable hops if not connect directly. This method assumes however that the ACL designated by the receive path is configured to control packets passing to the RP.
History
Many people have been given credit for creating the idea. Among them are Paul Traina and Jon Stewart. A similar method was also proposed by Ryan McDowell.