Re: How to invert more than one destination network?

[Antony Stone <Antony@Soft-Solutions.co.uk>]

On Monday 01 March 2004 3:58 pm, Gonzalo Parra wrote:

> Hi
>
> I have MASQUERADE in a box as a gateway using IPTABLES and I am using that
> box also for VPN... so for it to work I cant masquerade thaffic that goes
> to the other side of the VPN...
>
> This works for me:
>
> IPTABLES -t nat -A POSTROUTING -o $EXTIF -d \! 192.168.20.0/26 -j
> MASQUERADE
>
> but now I have another network at the other side of the VPN
> (192.168.40.0/26), so how can I invert two networks in the -d???

Depending on how your VPN is set up, are you sure that packets to the other 
end of it are going out through $EXTIF anyway?   I run VPNs using FreeS/WAN, 
and all the VPN traffic goes out through interface ipsec0, which I do not 
masquerade.

Anyway, assuming that you do need to do what you asked, try matching the 
packets you don't want to masquerade, first, then masquerading anything 
that's left:

iptables -A POSTROUTING -t nat -o $EXTIF -d 192.168.20.0/26 -j ACCEPT
iptables -A POSTROUTING -t nat -o $EXTIF -d 192.168.40.0/26 -j ACCEPT
iptables -A POSTROUTING -t nat -o $EXTIF -j MASQUERADE

Regards,

Antony.

-- 
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