[NTLUG:Discuss] Routing question

[Richard Geoffrion]

would this work for you?

#add a secondary IP address to the 192.168.100.1 nic
ifconfig eth0:1 192.168.100.200 broadcast 192.168.100.255 netmask
255.255.255.0

#portforward the packet type to the new address. (in this case port 80)
 ipmasqadm portfw -a -P tcp -L 192.168.100.200 80 -R 192.168.200.2 80

ok..well I know that's not exactly what you wanted...hmm...I think you are
wanting some sort of DNAT solution.  You need to NAT an entire ip address
(all ports) to another address.

Here is this from a previous post I left.
[snip]
I found this site ( http://www.linuxports.com/howto/networking/x1522.htm )
that discussed what I thought was going to be the answer to the one-to-one
NAT thang!  In practice it didn't work. Well, *I* didn't get it working
anyway...

Here's a snippet of what I read.

<snip>
Now, to translate addresses of incoming datagrams, the following command is
used:
    ip route add nat <ext-addr>[/<masklen>] via <int-addr>

This will make an incoming packet destined to "ext-addr" (the address
visible from outside Internet) to have its destination address field
rewritten to "int-addr" (the address in your internal network, behind your
gateway/firewall). The packet is then routed according to the local routing
table. You can translate either single host addresses or complete blocks.
Examples:

ip route add nat 195.113.148.34 via 192.168.0.2
ip route add nat 195.113.148.32/27 via 192.168.0.0

The First command will make internal address 192.168.0.2 accessible as
195.113.148.34. The second example shows remapping block 192.168.0.0-31 to
195.113.148.32-63.
</snip>

The problem I had is that I couldn't figure out what I was supposed to do
with the source addresses.  Was I suppose to bind them to the NIC or leave
them alone?  I *THINK* I'm supposed to bind them to the NIC.  I was able to
successfully get NAT working to do a PING, but then that was it.  Getting
the traffic from the local machine to go back out that same IP address
didn't work.

Anyway.  Food for thought.


----- Original Message -----
From: "Jack Snodgrass" <idiotboy at cybermail.net>
To: <discuss at ntlug.org>
Sent: Saturday, June 23, 2001 11:44 AM
Subject: [NTLUG:Discuss] Routing question


> I think that I've done this in the past, but I can't seem
> to figure out how to make it work now.
>
> I've got a box with two NIC cards:
> 192.168.100.1/255.255.255.0
> and
> 192.168.200.1/255.255.255.0
>
> I've got a second box that has a single NIC card
> 192.168.200.2/255.255.255.0
> and I want it to answer for
> 192.168.100.200/255.255.255.255.
>
> So I want anyone on the 192.168.100.0/255.255.255.0 network
> to route traffic for 192.168.100.200 via 192.168.100.1 but
> I don't want to add a static route on every 192.168.100.x
> PC for the special 192.168.100.200 route that goes via the
> .1 box.
>
> I have the 2.2.19 kernel.
>
> I thought that I could do a arp publish for the .200 box
> on the .1 box but that doesn't seem to work.
>
> Does anyone know what I'm doing wrong?
>
> jack
>
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