vRtrIfDHCPAutoFilter allows the router to automatically build
anti-spoofing filter lists. When this object is set to a non-zero
value, auto-filtering is enabled and a filter allowing only
PPPoE or DHCP traffic is established on the interface. The non-zero
value indicates the maximum number of entries that the auto-filter
can have. These entries are created by the agent upon snooping a
valid DHCP Reply packet and are used to allow traffic sourced by
the given DHCP-assigned IP address.