V-283821

Discussion

When Proxy ARP is enabled on a router, it allows that router to extend the network (at layer 2) across multiple interfaces (local area network [LAN] segments). Because proxy ARP allows hosts from different LAN segments to look like they are on the same segment, proxy ARP is safe only when used between trusted LAN segments. Attackers can leverage the trusting nature of proxy ARP by spoofing a trusted host and then intercepting packets. Proxy ARP should always be disabled on router interfaces that do not require it unless the router is being used as a LAN bridge.

Check Content

This requirement is not applicable for the DODIN Backbone.

Review the router configuration to determine if IP Proxy ARP is enabled on any external interfaces, as shown in the example below.

For each interface, use the command below, and in the "Proxy ARP Details" section, verify "Rem Proxy ARP" and "Local Proxy ARP" are disabled:

- show router interface "TO-PE2" detail | match Proxy

Proxy ARP Details
Rem Proxy ARP    : Disabled             Local Proxy ARP   : Disabled

Note: Proxy ARP is disabled by default. 

If IP Proxy ARP is enabled on any external interface, this is a finding.