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Implementing Cisco Networking Solutions by Harpreet Singh

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Unicast RPF

A router takes a forwarding decision based on the destination address, without any regard for the source of the IP packet. This is used by attackers to send attack packets on the network and using spoofed source addresses.

Cisco IOS software makes it possible to have the router check the source address of the packets before it takes a routing decision. Validating the source address can be a good way of checking that the addresses not in use are not sending packets on the network. This is done by using a feature called Reverse Path Forwarding (RPF). Since a router uses RPF as a standard mechanism for forwarding multicast packets, the feature when used for unicast packets is called unicast RPF or uRPF.

uRPF can be enabled in two ...

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