[CentOS] How to access one machine behind iptables, on different subnet?

Jorge Fábregas jorge.fabregas at gmail.com
Fri Oct 29 08:10:06 EDT 2010


On Friday 29 October 2010 04:22:52 Rudi Ahlers wrote:
> How do I give full access to all ports on  this IP, instead of forwarding
> every port?

Sure. That's called One-to-One NAT.  You'll do something like this:

iptables -t nat -I PREROUTING -d 192.168.1.20 -j DNAT --to-destination $GREEN

...where $GREEN is one ip on your 192.168.2.x network.  Then make sure you 
have the proper "allow" rules on the INPUT chain for your LAN ip ($GREEN).

The above was for ingress traffic.  Now, for egress traffic (for this internal LAN 
ip) you'll need to perform NAT as well:

iptables -t nat -A POSTROUTING -s $GREEN -j SNAT --to-source 192.168.1.20

Check out: 

http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch14_:_Linux_Firewalls_Using_iptables


HTH,
Jorge


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