Re: NAT setup

["Søren Kent Jensen" <soren@familie-jensen.dk>]

What you need is:
arp -s <Outside IP> <Outside MAC> pub
and a route to the <Outside IP> via the internal interface.

That should do the trick.

Regards
Søren Kent Jensen


----- Original Message -----
From: "Ramin Dousti" <ramin@cannon.eng.us.uu.net>
To: "Ben Becker" <bbecker2@cfl.rr.com>
Cc: <netfilter@lists.netfilter.org>
Sent: Saturday, December 20, 2003 1:30 AM
Subject: Re: NAT setup


> Hi Ben,
>
> Very interesting concept. There are two major parts to this:
>
> 1) Outbound packets from those static IP's to your gateway.
>    this can be done by enabling proxy-arp on your gateway
>    to answer to any arp request. This way the clients would
>    hand over their traffic to your gateway. Subsequently
>    your gateway would SNAT them and throw it on the Internet.
>
> 2) Inbound reply packets coming from the outside. This is a bit
>    tricky because, once they're in and de-SNATed, your gateway
>    must know where to send them to.  Since your gateway has only
>    one default route and no knowledge about those static IP's
>    behind it, it would automatically send the reply packets back
>    to the Internet. You might overcome this by blindly forwarding
>    these ESTABLISHED incoming packets through your internal interface
>    but you still need to somehow do an ARP for an IP outside your
>    LAN segment. At this point I don't have any simple solution
>    for that. But there are some very sharp ARP people here on the
>    list who could hack something together for you or give you
>    a pointer to an already hacked solution.
>
>
> Ramin
>
>
> On Fri, Dec 19, 2003 at 05:21:29PM -0500, Ben Becker wrote:
>
> > Hello everybody,
> >
> > I'm trying to figure out a way to set up basic NAT, but with the ability
> > to allow users on the local side to use any static IP configuration.
> > Quick Example: somebody has a static IP configured on their laptop,
> > stays at a hotel with Internet access, and will be able to browse the
> > Internet without changing their IP settings.
> >
> > My first question is: does anybody know what this feature is called?
> > Second question: Is it possible to do this with netfilter?  I'm thinking
> > this would require creating a new virtual interface for each user's
> > configuration to match their gateway (among other things), but I'm
> > hoping netfilter has some magical way of doing this (hoping).  If not,
> > does anybody know of any software that can do this?
> >
> > Regards,
> > Ben Becker
> >
>
>