Aliased ip's and DHCP

[Javier Ubillos]

On Nov 13, 2007 12:44 PM, Shane Kerr <Shane_Kerr at isc.org> wrote:
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> Simon Hobson wrote:
> > Javier Ubillos wrote:
> >
> >> The ips are form a /23 (or possibly a /22) subnet.
> >
> > Hmm, 5 is an odd number then !
> >
> >
> >> I have considered the "get more nics" solution, however, it would be
> >> nice to solve it using only one cable.
> >
> > The other thought was virtual nics and a bridge (as used in Xen) - I
> > don't know how hard it would be to set up an arrangement like this
> > without the overkill of also running at least one virtual machine to
> > host them.
>
> An easier way would be to manually simulate a single DHCP client that requests
> multiple leases. So, something like:
>
> - - Fire up a DHCP client with a client identifier.
> - - Get lease.
> - - Save lease information.
> - - Kill DHCP client *without* returning lease.
> - - Repeat 5 times with different client identifiers.
> - - Set the IP addresses on the same interface.
> - - Before leases expire, run the clients one at a time to renew the leases.
>
>
> If the DHCP server doesn't recognize the client identifiers, you might have to
> change the MAC address on the card ("ifconfig eth0 hw ether 00:11:22:33:44:55"
> in Linux).
>
>
> It's a bit brittle, but it just might work.
>
>
> I considered a DHCP option to allow the client to tell the server to send
> responses to a different port, which would allow multiple clients to run on a
> single interface. Mostly useful for testing, but also useful in this case. Of
> course, it entails some security problems, but not too bad since DHCP packets
> from the server go back to the MAC address that generated the packet, and DHCP
> tends to run on closed networks.
>
> - --
> Shane
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I will try that :)
If it works it'll be good enough :)

// Jav