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Linux ARPs too much

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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?

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kju on :

echo 1 > /proc/sys/net/ipv4/conf/($interface|default|all)/arp_ignore

bzw. bei Debian in /etc/sysctl.conf: net.ipv4.conf.($interface|default|all).arp_ignore = 1

1 = Reply only if tip is configured on the incoming interface 2 = Reply only if tip is configured on the incoming interface and is in same subnet as sip

Andreas Schiermeier on :

echo 1 > /proc/sys/net/ipv4/conf/($interface|default|all)/arp_filter

$KDIR/Documentation/networking/ip-sysctl.txt:

arp_filter - BOOLEAN 1 - Allows you to have multiple network interfaces on the same subnet, and have the ARPs for each interface be answered based on whether or not the kernel would route a packet from the ARP'd IP out that interface (therefore you must use source based routing for this to work). In other words it allows control of which cards (usually 1) will respond to an arp request.

    0 - (default) The kernel can respond to arp requests with addresses
    from other interfaces. This may seem wrong but it usually makes
    sense, because it increases the chance of successful communication.
    IP addresses are owned by the complete host on Linux, not by
    particular interfaces. Only for more complex setups like load-
    balancing, does this behaviour cause problems.

    arp_filter for the interface will be enabled if at least one of
    conf/{all,interface}/arp_filter is set to TRUE,
    it will be disabled otherwise

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