Re: First line in /etc/hosts
On Fri, 18 Feb 2005, Blars Blarson wrote:
> In article <firstname.lastname@example.org> email@example.com writes:
> >> > > Machines don't have IP numbers. Interfaces have IP numbers. Every machine
> >> >
> >> > Actually, that's not quite the case (as a number of users of Linux's ARP
> >> > implementation have found), though it's a good approximation.
> >This portion is unclear to me; could you shed some light ?
> >Do you mean:
> [wrong guesses omitted]
> A machine may use the same IP on multiple interfaces.
> A machine may use multiple IP addresses on a single interface.
> The two may be combined.
> A router may use proxy arp.
> A machine may use the same ethernet address on multiple interfaces on
> different physical networks. This tends not to work well with vlans.
> (switches pretending to be multiple networks)
Also: As far as the kernel is concerned, any local IP is local to *all*
interfaces, and it will happly reply to it (ARP and so on) if allowed to.
The rp_filter will often avoid trouble here, BUT routers often have to
disable rp_filter. So add some rules to the firewall make sure nothing gets
into 127.0.0.0/8 unless it is a local packet.
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot