Re: Two DHCP addresses on external interface

[Michael Gale <michael@bluesuperman.com>]

Ok ... here is the scoop ....

Originally I ran /sbin/dhcpcd -R -N -t 60 -h CO -d eth0

on my external interface to get a IP via DHCP from my ISP.

Now I want to run my PS2 behind the firewall and want the PS2 rules to
not be part of the standard firewall set.

So I get the MAC address of my PS2 and ran:
/sbin/dhcpcd -R -N -t 60 -h CO -I MAC-of-PS2 -d eth0:1

The out put was:
dhcpcd: MAC address = EXT NIC MAC 

but then BAM !!

dhcpcd: your IP address = Second IP via DHCP

So now if I run ifconfig I see

eth0 IP
eth0:1 second IP

Michael.


On Mon, 29 Dec 2003 01:31:57 +0000
Antony Stone <Antony@Soft-Solutions.co.uk> wrote:

> On Monday 29 December 2003 12:26 am, Michael Gale wrote:
> 
> > Hello,
> >
> > 	I think I have the answer, first I will find out the MAC address
> > 	of my
> > PS2 (packet sniffer) and then use dhcpcd w/ -I:
> > --snip-- man dhcpcd
> > -I <ClientID>
> >               Specifies the client identifier string.  dhcpcd uses
> >               the
> > default client identifier (MAC address of              the network
> > interface) if it is not specified.
> > --snip--
> >
> > I will specify the MAC of my PS2 ... then I can DNAT the traffic
> > back and forth to and from the PS2 :)
> >
> > Oh ... I think it will work :)
> 
> I'm not so sure - sorry.
> 
> The option you have found sends a client ID to the DHCP server, and if
> you don't specify the ID you want, it uses the MAC address.   However,
> I don't think that sending a different MAC address will give you the
> second DHCP client lease, because you can specify anything you like
> for the client ID (hostname is common), and you don't have to specify
> one at all, yet you still get a lease.
> 
> I wonder if maybe you have to do something unpleasant like acquire a
> lease, rename the /etc/dhcpc/dhcpcd-eth0.* files, and acquire another
> one, this time faking the MAC address (but I'm not sure how...)?
> 
> Another horrible suggestion is to put another ethernet card in your
> firewall, plug it into the hub alongside your existing external
> interface, then acquire leases on both eth0 and eth1 (which just
> happen to be connected to each other through the hub).   Normally I
> would say to people "No! Don't have two interfaces on the same subnet,
> and don't connect two interfaces to the same hub" but in this case it
> might be a workable solution?
> 
> Regards,
> 
> Antony.
> 
> -- 
> A: Because it messes up the order in which people normally read text.
> Q: Why is top-posting such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing on usenet and in e-mail?
> 
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> 
> 


-- 
Hand over the Slackware CD's and back AWAY from the computer, your geek
rights have been revoked !!!

Michael Gale
Slackware user :)
Bluesuperman.com