NAT vs Public IP Range info needed, please

[Stacey Roberts]

Hi Kevin,
    Thanks for replying.

----- Original Message -----
From: "Kevin Stevens <freebsd at pursued-with.net>"
To: To Stacey Roberts
Date: Sat, 12 Jun, 2004 20:11 BST
Subject: Re: NAT vs Public IP Range info needed, please

> 
> On Jun 12, 2004, at 09:46, Stacey Roberts wrote:
> 
> >The ISP's DSL package includes 8 static ip addresses: -
> >1 - network addr
> >1 - broadcast addr
> >1 "router" address
> >5 usable ip addresses
> 
> >The -redirect_address syntax is as follows:
> >-redirect_address localIP publicIP
> >localIP         The internal IP address of the LAN client.
> >publicIP        The external IP address corresponding to the LAN 
> >client.
> 
> >What I would like to know is if it is possible to do to following: -
> >Given that the 5 usable public IP's are: 1.1.1.4, 1.1.1.5, 1.1.1.6, 
> >1.1.1.7 & 1.1.1.8
> >1] G'Way host is assigned its own public IP - 1.1.1.3
> >2] LAN hosts' (all) traffic is NAT'd using one of the other public 
> >IP's - 1.1.1.4
> >3] Remaining 4 public IP addresses are left to be used other purposes 
> >(eg: "true" address redirection to a DMZ-host, that is not a member of 
> >the internal LAN subnet)
> 
> Not sure I understand (it would help if you used a real public /29 to 
> illustrate, your example doesn't follow legal subnet rules).  in 1) 
> above, the gateway host ip has to come out of the usable address pool, 
> which you designate .4 - .8.  So in 1) you could have the gateway IP as 
> .4.  In 2) You have .5 assigned for many-one NATing (in the Linux world 
> they'd call this ip masquerading).  In 3) you'd have THREE public 
> addressed left that could be used for one-one NAT.

Well.., despite the actual IP addresses used, you've got the general picture correct there. What I'm after is to be able to define an IP address that is *not* that which is assigned to the publicly-facing interface of the gateway as the nat ip address for internal lan hosts.

> 
> >As you see, the g'way's public ip is not being used for NAT'ing 
> >internal hosts' outgoing traffic, but another ip from within the 
> >assignied public ip address range. My reading of the NAT chapter does 
> >not suggest that there is a way to define the public IP with which 
> >traffic is to be translate. Is this functionality not supported, or 
> >have I missed something when reading the various sections?
> 
> It is AFAIK, they just don't use it in the example.

I've seen your follow-up mail arrive, where you've included the pointer to the alias -switch to natd(8). Cheers for that.., I'll have a read and try to work this out.

Thanks again for taking the time.

Regards,

Stacey

> 
> KeS
> 
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