I had a case where I wanted to redirect traffic to my server on a specific port to a different server. In my instance, I had a machine with CentOS installed, which allowed me to use Firewalld to achieve this.
Two commands are sufficient.
First, activate masquerade in a desired zone. (I simply use public here)
sudo firewall-cmd --zone=public --add-masquerade --permanent
Second, configure the specifics.
sudo firewall-cmd --zone=public --add-forward-port=port=5000:proto=tcp:toaddr=123.456.78.9:toport=5000
Obviously, there are a few parameters that should be changed per situation. First, 'port=' should be set to the port of the incoming traffic that should be forwarded, 'toaddr=' should be the IP of the server the traffic should be forwarded to, 'toport=' determines what port on the other server the traffic will be directed to.