[OT]two networks, one nic

Nikos Vassiliadis nvass at teledomenet.gr
Tue Nov 14 08:51:43 UTC 2006

On Tuesday 14 November 2006 07:52, jekillen wrote:
> Hello FreeBSD users,
> I have been operating under the assumption that
> the same network interface card cannot handle two
> different networks. But then I seem to have seen
> an example in one of the OReill¥ books on networking
> that had one interface with one assigned inet address
> and also aliased with another address that could only
> be on another network. If I understood that right, it
> seems to imply that I can use one Network interface
> card for at least two different networks, like so;
> 192.168.1.<somthing> and
> alias 172.0.0.<something>
> or;
> 192.168.1.<something>
> alias 192.168.2.<something>

or you can keep your secondary addresses to a
loopback interface:
ifconfig create lo1
ifconfig lo1
ifconfig lo1 alias
ifconfig lo1 alias
ifconfig lo1 alias
ifconfig lo1 alias

> If this is possible is it accomplished via a special routing?

No, nothing special. Your box has:

your upstream router has:

If your router is willing to forward packets to/from your
addresses, everything will be correct(read bellow though).

> My concern is that I have a laptop with one network
> interface, built in,  but would like to access it both at
> a public static address and a private network address.
> Is this possible?

Your private network address will not be routed by
your ISP. You have to use "real", routable addresses.
These are routable across the internet, the private
addresses aren't. They are for private use and should
be filtered.

Please give more information, if I didn't cover your

HTH, Nikos

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