Re: NATing a range of IPs

[Frederik Rousseau <fred@cmelectronics.be>]

> Is it possible to NAT a range of IPs?  Like for example:
>
> iptables -t nat -A PREROUTING -p tcp -s <range of IPs>  --dport 80 -j
> REDIRECT --to-port 13001
>
> As you can see what I would like to do is redirect port 80 from the
> range of IPs (in this case 65.18.71.1 - 65.18.71.240) to port 13001.
> It works great is I try one IP, or the whole block, I'm just unsure of
> how you represent a range?  I see references to a IP range in the man
> pages, but no examples.

iptables is using a netmask to define an IP range.
Exsamples: 

1) iptables -t nat -A PREROUTING -p tcp -s 10.20.1.0/24  --dport 80 -j 
REDIRECT --to-port 13001

gives you all the IPs from 10.20.1.1 to 10.20.1.254

2) iptables -t nat -A PREROUTING -p tcp -s 10.103.1.128/25  --dport 80 -j 
REDIRECT --to-port 13001

gives you all the IPs from 10.103.1.129 to 10.103.1.254


On http://jodies.de/ipcalc you find a nice tool to define the netmasks for the 
right IP ranges.

Regards,
Fred