[Herefordshire] Routing two subnets

[Mark Broadbent]

On Thu, 2004-10-28 at 21:06 +0100, Chris Bond wrote:

> http://www.linuxforums.org/forum/ntopic25532.html seems to suggest you
> need to fwd the packets using iptables as the default routing is not
> doing nothing – not sure what lines need to be added in a two-subnets
> though…


They are referring to masquerading (source address rewriting).  Your
doing 'normal' routing, Box A will send a packet through the gateway
(Linux Box) to Box B and Box B will reply through through the gateway to
Box A - no address rewriting needed.

Like I said earlier we need the output of 'ipconfig'/'ifconfig' and
'route' on all three machines to see what's going on (and the output of
'cat /proc/sys/net/ipv4/ip_forward' just for a sanity check).

Thanks
Mark


>  
> 
>                                    
> ______________________________________________________________________
> 
> From:Mark Broadbent [mailto:markb at wetlettuce.com] 
> Sent: 28 October 2004 9:03 PM
> To: chris at logics.co.uk; Herefordshire Linux Users Group.
> Cc: mherbert at redhat.com
> Subject: RE: [Herefordshire] Routing two subnets
> 
> 
>  
> 
> On Thu, 2004-10-28 at 20:43 +0100, Chris Bond wrote: 
> 
> 
>  
> Might have not made it clear I can route on the linux box perfectly its on a
> remote machine that where the default gateway is set to route that segment
> that it doesn't route via the linux box.
>  
> -----Original Message-----
> From: Chris Bond [mailto:chris at logics.co.uk] 
> Sent: 28 October 2004 8:41 PM
> To: mherbert at redhat.com; herefordshire at mailman.lug.org.uk
> Subject: RE: [Herefordshire] Routing two subnets
>  
> Already done that but still doesn't route the packets!  Iptables -L shows
> default ACCEPT so its not that blocking it... aby more ideas?
> 
> 
> 
> I assume your network is laid out like somewhat like:
> 
> [Box A]<---Subnet 1-->[eth? "Linux Box" eth?]<--Subnet 2-->[Box B]
> 
> Starting with basics I'll assume your attempting to ping Box B from
> Box A.  The output from this would be useful, even more useful would
> be the packet capture whilst your pinging Box B (using tcpdump or
> ethereal).  But to start with if give us the output from the 'route'
> command on all the boxes (plus a corresponding 'ifconfig' [Linux] or
> 'ipconfig /all' [Windows]) and we can work from there.
> 
> Thanks
> Mark
> 
> 
> 
> -- 
> Mark Broadbent <markb at wetlettuce.com> 
> 
> 
> 
>  
> 
> 

-- 
Mark Broadbent <markb at wetlettuce.com>
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