On Sunday 07 July 2002 12:51 pm, Thomas Hilgert wrote:

> Here is a small picture and the iptables commands
>
> #  ETH1: External
> #  ETH2: DMZ 10.2.0.1
> #  ETH0: LAN 10.1.0.1

> # SNAT all outgoing traffic
> #
> iptables -t nat -A POSTROUTING -o  eth1 -j MASQUERADE
> #
> # DNAT all incoming traffic to out DMZ WEB and MAIL Server (10.2.0.2)
> #
> iptables -t nat -A PREROUTING -i eth1 -j DNAT --to 10.2.0.2

I suggest you change that last rule so that it is specific to the services 
you actually want to be accessed:

1. It might solve your problem
2. It's an *awful* lot more secure - at present you're making the whole 
machine 10.2.0.2 accessible to the Internet with no filtering

iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 25 -j DNAT --to 10.2.0.2
iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j DNAT --to 10.2.0.2

Add more rules with appropriate port numbers if you want to make your ftp, 
ssh, dns, https and http-proxy servers accessible to the outside as well.

By the way, whilst you're at it, you might like to tidy up your name server 
configuration - it seems to have an awful lot of redundant entries in it....

 

Antony.

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