Hi!
My question is about ARP behaviour: Why does my machine answer ARP
requests for eth1 on eth0, even if the address on eth1 has scope link and
arp_filter is on? What do I have to do to prevent this?
I am aware that this issue was already discussed, but I could not find a
solution to the problem even in the long threads. The recommendation
seems to be to turn on arp_filter, but that doesn't help a bit.
This is my setup (output beautified a bit):
======================================================================
[root@paco00 all]# ip addr show
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 brd 127.255.255.255 scope host lo
2: eth0: <BROADCAST,MULTICAST,PROMISC,UP> mtu 1500 qdisc pfifo_fast qlen
100
link/ether 00:01:02:b9:18:8b brd ff:ff:ff:ff:ff:ff
inet 129.187.154.217/24 brd 129.187.154.255 scope global eth0
inet 129.187.154.218/24 brd 129.187.154.255 scope global secondary
eth0:0
inet 129.187.154.219/24 brd 129.187.154.255 scope global secondary
eth0:1
3: eth1: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 100
link/ether 00:60:08:f5:ec:0e brd ff:ff:ff:ff:ff:ff
inet 10.187.185.12/24 brd 10.187.185.255 scope link eth1:0
inet 192.168.1.254/24 brd 192.168.1.255 scope link eth1
[root@paco00 all]# ip route show
10.187.185.11 dev eth1 scope link
129.187.154.0/24 dev eth0 proto kernel scope link src 129.187.154.217
192.168.1.0/24 dev eth1 proto kernel scope link src 192.168.1.254
10.187.185.0/24 dev eth1 proto kernel scope link src 10.187.185.12
127.0.0.0/8 dev lo scope link
default via 129.187.154.254 dev eth0
[root@paco00 all]# cat /proc/sys/net/ipv4/conf/{all,eth0,eth1}/arp_filter
1
1
1
======================================================================
This shows the problem:
======================================================================
root@pc40:/ > arping 192.168.1.254
ARPING 192.168.1.254 from 129.187.154.153 eth0
Unicast reply from 192.168.1.254 [00:01:02:B9:18:8B] 0.837ms
======================================================================
I'm using kernel 2.4.6 from Linus, machine is a dual PIII450, 512MB RAM
eth0: 3Com PCI 3c905C Tornado, PROMISC because of arpwatch running
eth1: 3Com 3C985 Gigabit Ethernet
Ciao,
Roland
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