Routing all data from one IP to another in linux (centos)

mmvika · 09-10-2015, 09:32 AM

I like to route all data that is coming in at one IP address of my server to another IP address somewhere else on the internet.

For example:
My server has 2 IP addresses: 1.1.1.1 and 2.2.2.2
All the data that is coming in at IP address 2.2.2.2 should be forwarded to adres 3.3.3.3 (this address it not in my network)
So if I surf with a browser to http://2.2.2.2/ this should be the same outcome as going to http://3.3.3.3/

I like to do this from within the console of a centos linux distro.

lazydog · 09-10-2015, 10:43 AM

Have a look at iptables DNAT rules.

dpcioc · 09-12-2015, 10:40 PM

Hello!
So it should be:

Code:

iptables -t nat -A PREROUTING -d 2.2.2.2 -j DNAT --to-destination 3.3.3.3

Take a look here. The information enters PREROUTING, then goes into FORWARD then exits. By default forwarding is allowed but if it isn't:

Code:

iptables -A FORWARD -d 3.3.3.3 -j ACCEPT
iptables -A FORWARD -s 3.3.3.3 -j ACCEPT

Your kernel must also accept forwarding, edit /etc/sysctl.conf. Make sure you have net.ipv4.ip_forward = 1 and it should not be commented. After making changes to sysctl.conf reload it:

Code:

sysctl -p /etc/sysctl.conf