Hi,
> > >>> In contrast, on Linux (by default), it
> > >>> responds as long as the target IP address in ARP Request matches with
> > >>> any "local" IP address on the system, which is not necessarily an IP
> > >>> address assigned to the interface through which the ARP request is
> > >>> received.
> > >>
> > >> This sounds like "proxy ARPing" is enabled by default on your
> > >> particular flavor of Linux. I don't think they all do that,
> > >> hopefully, any more than ipforwarding should be enabled by default
> > >> just because a machine has two NICs.
> > >
> > > What Motonori Shindo described is actually the default behaviour for
> > > Linux kernels (at least my 2.6.8-kernel does it by default).
>
> It seems that it has been so for a long time since 2.2 kernel days.
>
> > > It could be
> > > seen as a sort of proxy-arp, but only for the host itself, not other
> > > systems. Let me try to describe when it happens. Say you have
> > > 192.168.42.42 bound on eth0 and have eth1 connected to some ethernet
> > > LAN. When a host on that eth1-connected LAN sends an 'arp who-has
> > > 192.168.42.42', a Linux system will answer that arp-request with it's
> > > eth1 MAC-address, although the IP-address is bound on eth0 and the arp
> > > request comes in on eth0. FreeBSD obviously doesn't do this.
FYI, proxy ARPing for a whole subnet might be enabled on Linux with
the following sysctl, in order to create what they call a "pseudo-bridge" :
/proc/sys/net/ipv4/conf/<iface>/proxy_arp
When a Linux box is a router between two subnets A and B, if a host on A
issues an ARP request about a host on B (because they think to be on
the same physical network), the Linux box will reply with its own MAC
address, and conversely.
> > > Incoming traffic on
> > > the 'wrong' interface will gladly be accepted, too. This broke things
> > > for me, because I didn't want to have that certain IP-address accessible.
This behaviour can be controlled with :
/proc/sys/net/ipv4/conf/<iface>/rp_filter
These sysctl are explained in the Linux kernel source :
linux/Documentation/networking/ip-sysctl.txt
Please, don't blame me because this is not FreeBSD-centric.
Regards,
--
Jeremie Le Hen
< jeremie at le-hen dot org >< ttz at chchile dot org >
_______________________________________________
freebsd-net@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-net
To unsubscribe, send any mail to "[EMAIL PROTECTED]"
