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What is Cisco uRPF?
Another great security feature within every Cisco IOS ISR is uRPF, Unicast Reverse Path Forwarding. This nifty little feature has the router verify the source of any IP packets received is reachable via the routing table. uRPF is used to prevent common spoofing attacks and follows RFC 2827 for ingress filtering.
What is RPF failure?
PIM is known as Protocol Independent Multicast routing because it does not exchange its own information about the network topology. Instead it relies on the accuracy of an underlying unicast routing protocol like OSPF or EIGRP to maintain a loop free topology.
What is RPF check?
When creating multicast routing entries, the multicast routing protocol uses the reverse path forwarding (RPF) check to ensure the multicast data delivery along the correct paths. The RPF check also helps avoid data loops. Unicast routing table—Contains unicast routing information.
What is URFP?
uRPF is a security feature that prevents these spoofing attacks. Whenever your router receives an IP packet it will check if it has a matching entry in the routing table for the source IP address.
What is deny ICMP reverse-path check?
Event 106021 is generated when a packet that does not have a source address represented by a route is discarded by unicast RPF, which would have been enabled with ‘IP verify reverse-path’ command. …
How to protect your network with unicast RPF?
You can protect a network by applying unicast RPF check feature at the edge (on customer facing interfaces) of the network. In an ISP environment, this can impact the network which can impose on a scaled setup.
How does unicast reverse path forwarding ( RPF ) work?
Unicast Reverse Path Forwarding (RPF) functions in three distinct modes and can potentially help reduce a router’s attack vector, specifically from spoofed IP addresses. In strict mode, a router will inspect and check an incoming packet’s source IP address against it’s Forwarding Information Base (FIB) table for a matching route.
Why does unicast drop traffic in loose mode?
Dropping this legitimate traffic could occur when asymmetric routing paths are present in the network. When administrators use Unicast RPF in loose mode, the source address must appear in the routing table.
How to check unicast statistics on a firewall?
The show ip verify statistics command can provide information about Unicast RPF statistics on a PIX/ASA/FWSM firewall. The following example shows 21 drops by Unicast RPF on the outside interface and 2738 packets dropped by Unicast RPF on the inside interface.