Proxy Arp

iproute2 deprecated command

# -- this is deprecated; use arp or kernel proxy_arp instead -- #
ip neighbor add proxy 192.168.100.1 dev eth0
# -- this is deprecated; use arp or kernel proxy_arp instead -- #

# -- this is the equivalent command that should be used instead -- #
arp -s 192.168.100.1 -i eth0 -D eth0 pub
# -- this is the equivalent command that should be used instead -- #

For a long discussion of this topic, see this discussion on the kernel mailing list.