Re: Internal PC/external Gateway

[Jason Opperisano <opie@817west.com>]

On Sat, May 14, 2005 at 09:30:10PM +0300, Sadus . wrote:
> Before continuing, thanks alot for your help.
> 
>                                            +------------+        
>                                            |            |       |
>                                        ----+ Provider 1 +-------
> 192.168.1.2                          |   | 10.2.2.1  |     /
>    PC1__/  \_         +------+-------+ |   +------------+    |
>    _/        \__      |              | |                    /
>   /             \     | 10.2.2.253 | |                    |
>  | Local network -----+Linux GW  eth0|-                     |Internet
>   \_           __/    |192.168.0.141 |                   |
>     \__     __/       |              | |                    \
>    PC2 \___/          +------+-------+ |   +------------+    |
> 192.168.1.3                          |   |            |     \
>                                        ----+ Provider 2 +-------
>                                            |192.168.0.173     |
>                                            +------------+        
> 
> so a little reminder. i just want 192.168.1.3 to take Internet from
> 192.168.0.173
> my GW has as you see has 2 IPs in eth0, and i can reach both of my
> Providers with that setup.
> 
> btw, is there any article to read about the priority of rules while
> writing an iptables script?

yeah--first match wins for all terminating targets.  a good tutorial in
general is:

  http://iptables-tutorial.frozentux.net/iptables-tutorial.html

so it looks like we need:

  iptables -t nat -A POSTROUTING -o eth0 -s 192.168.1.2 \
    -j SNAT --to 10.2.2.253
  iptables -t nat -A POSTROUTING -o eth0 -s 192.168.1.3 \
    -j SNAT --to 192.168.0.141

  echo 202 T2 >> /etc/iproute2/rt_tables

  ip route add default via 192.168.0.173 table T2

  ip rule add from 192.168.1.3 table T2

  ip route flush cache

hope this helps...

-j

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