PlayingExperimenting with arping, I found the following behavior:
$ sudo arping -c 1 10.202.202.254 ARPING 10.202.202.254 60 bytes from 00:0f:20:d4:07:e0 (10.202.202.254): index=0 time=196.934 usec --- 10.202.202.254 statistics --- 1 packets transmitted, 1 packets received, 0% unanswered $ sudo arping -c 1 10.101.2.1 ARPING 10.101.2.1 60 bytes from 00:0f:20:d4:07:e0 (10.101.2.1): index=0 time=168.085 usec --- 10.101.2.1 statistics --- 1 packets transmitted, 1 packets received, 0% unanswered $
wtf? 10.101.2.1 is my default gateway (running a recent Linux 2.6 kernel), so it is ok to answer ARP requests. 10.202.202.254 is bound on the same box, but on a different interface, so I don't think it is ok to answer ARP requests for that IP address on "my" interface, as it confuses some "what network segment am I on today" mechanisms.
Is there some /proc setting where I can disable this rather generous ARP behavior?