Showing posts from July, 2013

uRPF - Unicast Reverse Path Forwarding

Cisco Docs: Cisco Docs: Secure DATA PLANE>Security Configuration Guide: Unicast Reverse Path Forwarding

The Unicast RPF feature helps to mitigate problems that are caused by the introduction of malformed or forged (spoofed) IP source addresses into a network by discarding IP packets that lack a verifiable IP source address

Configure the receiving interface, which allows Unicast RPF to verify the best return path before forwarding the packet on to the next destination. For example, verify if the SOURCE IP is reachable via that exact interface:
(config-subif)#ip verify unicast source reachable-via ?
any  Source is reachable via any interface
rx   Source is reachable via interface on which packet was received <-EXACT INTERFACE

#sh ip int s1/0.21 | b verify
  IP verify source reachable-via RX
   0 verification drops
   0 suppressed verification drops
   0 verification drop-rate


Zone Based Firewall

Cisco Docs: Secure DATA PLANE>Security Configuration Guide:Zone-Based Policy Firewall

To configure the Zone Based FW, the approach is somewhat similar to the MQC method in the QoS configuration.

STEP 1> Start by creating a class map of INSPECT TYPE, and match HTTP, and DROP everything else:
(config)#class-map type inspect match-any OUTSIDE
(config-cmap)#match protocol http
(config-pmap)#class type inspect OUTSIDE 

STEP 2> Create a inspect type POLICY-MAP that matches the defined CLASS-MAP, and INSPECTS:
(config)#policy-map type inspect OUTSIDE_POLICY
(config-pmap)#class OUTSIDE
(config-pmap-c)#inspect ?
  WORD  Parameter-map (inspect) name <PARAMETER MAP CAN BE DEFINED to tune the inspection

STEP 3> Define the SECURITY ZONES for the interfaces you need, and assign them to the interfaces:
(config)#zone security DMZ