ip assignments

[Nikos Vassiliadis]

On Sunday 09 September 2007 21:50, jekillen wrote:
[snio]
> I found
> that each of the interfaces have to be assigned an address
> in a different subnet. for them to both be usable.
> Q: Is this characteristic of tcp/ip in general, or specific
>      to FreeBSD?

Imagine the following situation:
NIC0 10.0.0.1/24
NIC1 10.0.0.2/24
The kernel gets a packet from 10.0.0.3.
Where should the reply would be send from?
NIC0 or NIC1?

Situation #2
NIC0 10.0.0.1/24
NIC1 10.0.0.2/24
NIC2 192.168.0.1/24
The kernel gets a packet for 10.0.0.3.
Where this packet should be forwarded to?

So, FreeBSD does not accept such IP configurations,
to keep things sane. Other operating systems accept
such configurations, but you have to be careful
and you have to know what you are doing, in order
to prevent self foot-shooting. Of course there are
valid ways to achieve the same results without
the foot-shooting factor. Using aliases with /32
mask is one. What's wrong with IP_alias/32?

HTH

Nikos