[LARTC] Re: Routing/NAT question

[Tom Diehl <tdiehl@rogueind.com>]

On Fri, 13 Sep 2002, Martin A. Brown wrote:

Hi Martin,

First I want to apologize for my inability to explain this correctly. I feel 
pretty stupid right now. I will try again.

>  : > (or use the traditional redhat ifcfg-eth1:0 technique)
>  : > 
>  : > and tell the internal machines that the default gateway is 10.140.227.245.
>  : 
>  : OK, but as I said in the diagram below my connection to the internet is
>  : on wan0 via iptables and NAT. Will not 2 default routes confuse things?
> 
> default gateway on the linux box
> - - - - - - - - - - - - - - - - - -
> I think you missed my drift--your linux box will have one default route to 
> the T1 (wan0) peer endpoint or ISP access router.  (Yes, Greg Scott is 
> right when he mentions that linux supports multiple routing tables, but 
> you do not need them for this scenario.)
> 
> default gateway on internal machines
> - - - - - - - - - - - - - - - - - -
> Each of your internal machines which is locally connected to the same
> ethernet/IP network as the linux box will use the linux box as its default
> gateway.  Machines in the 10.140.227.224/27 network will use
> 10.140.227.245 as a default gateway.  Machines in 192.168.101.0/24 will
> use 192.168.101.5 as a default gateway.

OK, I understand this but I want the 192.168.101.0/24 machines to be able to 
talk to the 10.140.227.224/27 network also but only for the subnets listed 
below. All other traffic goes out the default route to the internet (wan0).
I am trying to eliminate the 2nd pc on some desks and to do that 
the machines on the 192.168.* net must be able to talk to the 10.* net.

> 
>  : In addition I only want traffic for 8 the following specific subnets
>  : routed down the 10.140.x.x pipe. They are 10.140.0.0/16, 10.141.0.0/16,
>  : 10.142.0.0/16, 151.193.141.0/24, 162.92.160.0/24. All other traffic
>  : should go out to the internet via wan0.
>  : Does this make sense?
> 
> Sure....seems clear to me.  You have a couple of internal networks 
> behind a router on the locally connected 10.140.227.245/27 network.  
> So, assuming that 10.140.227.254 is the gateway to your remote 
> networks*:
> 
> # route add -net 10.140.0.0 netmask 255.255.0.0 gw  10.140.227.254
> # route add -net 10.141.0.0 netmask 255.255.0.0 gw  10.140.227.254
> # route add -net 10.142.0.0 netmask 255.255.0.0 gw  10.140.227.254
> # route add -net 151.193.141.0 netmask 255.255.255.0 gw  10.140.227.254
> # route add -net 162.92.160.0 netmask 255.255.255.0 gw  10.140.227.254
> 
> And repeat as necessary up to your eight subnets.
> 
> Really though, there's nothing LARTC about this setup--sure you are using
> Sangoma's (wonderful) T1 card, but you don't need any of the fancy routing
> tricks and tips usually discussed in this forum.

I really love the wanpipe cards. We bought and deployed almost a dozen of them.
As far as the fancy tricks discussed here I think I really do need them but
I am just not good at explaining what I am trying to do. Sorry. :-(

> 
> * If I recall correctly, you are using RedHat...you can append the
>   following lines to your /etc/sysconfig/static-routes file to have these
>   routes added at network restart (boot):
> 
>     eth0 net 10.141.0.0 netmask 255.255.0.0 gw  10.140.227.254
>     eth0 net 10.142.0.0 netmask 255.255.0.0 gw  10.140.227.254
>     eth0 net 151.193.141.0 netmask 255.255.255.0 gw  10.140.227.254   
>     eth0 net 162.92.160.0 netmask 255.255.255.0 gw  10.140.227.254
> 
>   Of course, you should use the correct ethernet interface.....

Understood.

Thanks for the help everyone. I am not ready to give up yet. Your patience
is appreciated.

-- 
.............Tom	"Nothing would please me more than being able to 
tdiehl@rogueind.com	hire ten programmers and deluge the hobby market 
			with good software." -- Bill Gates 1976

   			We are still waiting ....

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