I knew this was practically impossible. But technicaly it is. So I thought maybe 
someone has a clue about another tool, or some tricky way to do something like this. I 
personally think that this *should* be a feature in the next version of ipfilter. I 
mean, a syntax that lets users to change both source and destination IPs (and ports of 
course) with a single command. Like the following for example;

fxp0 external
fxp1 internal

napt fxp0 from any to fxp0/32 port 20032 -> from fxp1/32 to 10.21.3.1 port 23

-Ali

-----Original Message-----
From: Andrew Kopeyko [mailto:[EMAIL PROTECTED]] 
Posted At: Friday, August 16, 2002 2:23 PM
Posted To: IPFilter
Conversation: How can I do this nat?
Subject: RE: How can I do this nat?


On Fri, 16 Aug 2002, Ali (ipfilter) wrote:

> Andrew,
>
> I've read the manuals and FAQ carefully.
>
> RDR changes only the destination IP address/port in the NAT. What I 
> want is to also change the source address. This is done with MAP, but 
> I want to do both.
>
> Of course the packet is sent from 10.21.3.254 to destination IP 
> 10.21.3.1 but RDR doesn't change the source IP address (X.Y.Z.T in my
> example) of the packets.

O! I have mis-understood you.

So, the answer is very short - "seems to be impossible". IMHO, ipnat can't change 
source addr AND destination addr of the packet; only one of them can be altered.

Am I right, Darren?


To solve your problem, Ali, you should use some proxies - eg. 'delegate' or 'fwtk'

Why can't you setup 'default gateway' on your internal host? In this case you would be 
able to use RDR rule.


> -----Original Message-----
> From: Andrew Kopeyko [mailto:[EMAIL PROTECTED]]
> Posted At: Friday, August 16, 2002 11:59 AM
> Posted To: IPFilter
> Conversation: How can I do this nat?
> Subject: Re: How can I do this nat?
>
>
> On Fri, 16 Aug 2002, Ali (ipfilter) wrote:
>
> > Hi all,
> >
> > External interface: A.B.C.D
> > Internal network:   10.21.3.0/24
> > Firewall/router:    10.21.3.254
> > One special host:   10.21.3.1
> >
> > What I want is to allow outsite to telnet into my special host thru 
> > a different external port (not 23). Lets say 20023. So what I want 
> > is to map A.B.C.D:20023 to 10.21.3.1:23
>
> You must use RDR to perform this:
>
> rdr <ifname> A.B.C.D port 20023 -> 10.21.3.1 port 23 tcp
>
> >
> > But when I do this, I also need to 'map' the source address as 
> > 10.21.3.254 because the special host cannot answer to IP addresses 
> > other than 10.21.3.0/24 network (seems like it doesn't have a 
> > default gw).
>
> Connection to your "special host" will be done from 10.21.3.254 
> address.
>
> >
> > Shortly, from a given X.Y.Z.T external IP, I need to NAT something 
> > like this;
> >
> > X.Y.Z.T -> A.B.C.D:20023 will change as
> > 10.21.3.254:[some nat port] -> 10.21.3.1:23
> >
> > Can I do this?
>
> read man carefully and read FAQ
>
>
>

-- 
Best regards,
Andrew Kopeyko <[EMAIL PROTECTED]>

  Rambler Co.   http://www.rambler.ru/
  phone :       +7 095 745-3619



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