Two DHCP addresses on external interface

Two DHCP addresses on external interface

[Michael Gale]

Hello,

	I have a strange question, right now I have a firewall box at home and
behind it is my web, mail and FTP server.

Plus the rest of my computers and my wife's PC.


I got a PS2 for Christmas ... I know I will never grow up really :)

So I want to play online but it uses strange ports and they do not seem
to be listed anywhere. Plus I can not host any games if I am behind a
firewall unless I forward connections on ports about 1024 to the PS2 IP
which could break FTP and other things.

So my ISP provides a second IP free of charge :0 so I have them provide
me with one. So now I can plug two PC's into a HUB and the cable modem
into the HUB and each PC gets it's own IP via DHCP. 

I would like to have my firewall get both IP's then I would be able to 
have some control as to what packets go to and from the PC also I can do
some bandwidth monitoring.

I have used virtual IP's on linux boxes before with no problems but can
I have a box get both IP's via DHCP ???

Right now it gets one:
/sbin/dhcpcd -t 60 -h CO -d eth0

I tried to get a second one by:
/sbin/dhcpcd -t 60 -h CO -d eth0:1 

But it did not work :(

.. any ideas ??? do I need to fact another MAC address ???? now I am 
thinking


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rights have been revoked !!!

Michael Gale
Slackware user :)
Bluesuperman.com 

Re: Two DHCP addresses on external interface

[Michael Gale]

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 :)

Michael.



On Sun, 28 Dec 2003 17:07:33 -0700
Michael Gale <michael@bluesuperman.com> wrote:

> Hello,
> 
> 	I have a strange question, right now I have a firewall box at
> 	home and
> behind it is my web, mail and FTP server.
> 
> Plus the rest of my computers and my wife's PC.
> 
> 
> I got a PS2 for Christmas ... I know I will never grow up really :)
> 
> So I want to play online but it uses strange ports and they do not
> seem to be listed anywhere. Plus I can not host any games if I am
> behind a firewall unless I forward connections on ports about 1024 to
> the PS2 IP which could break FTP and other things.
> 
> So my ISP provides a second IP free of charge :0 so I have them
> provide me with one. So now I can plug two PC's into a HUB and the
> cable modem into the HUB and each PC gets it's own IP via DHCP. 
> 
> I would like to have my firewall get both IP's then I would be able to
> 
> have some control as to what packets go to and from the PC also I can
> do some bandwidth monitoring.
> 
> I have used virtual IP's on linux boxes before with no problems but
> can I have a box get both IP's via DHCP ???
> 
> Right now it gets one:
> /sbin/dhcpcd -t 60 -h CO -d eth0
> 
> I tried to get a second one by:
> /sbin/dhcpcd -t 60 -h CO -d eth0:1 
> 
> But it did not work :(
> 
> .. any ideas ??? do I need to fact another MAC address ???? now I am 
> thinking
> 
> 
> -- 
> Hand over the Slackware CD's and back AWAY from the computer, your
> geek rights have been revoked !!!
> 
> Michael Gale
> Slackware user :)
> Bluesuperman.com 
> 


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

Michael Gale
Slackware user :)
Bluesuperman.com 

Re: Two DHCP addresses on external interface

[Antony Stone]

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?

                                                     Please reply to the list;
                                                           please don't CC me.

Re: Two DHCP addresses on external interface

[Michael Gale]

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?
> 
>                                                      Please reply to
>                                                      the list;
>                                                            please
>                                                            don't CC
>                                                            me.
> 
> 


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

Michael Gale
Slackware user :)
Bluesuperman.com