Port forward to a port on the same machine

iptables -t nat -A PREROUTING -p tcp --dport 25570 -j REDIRECT --to-port 25565

This assumes you're not routing traffic for an entire network through this box and that if you were there's no expectation that traffic destined for other hosts will be on that port

It is worth noting the the accepted answer only applies for other network hosts connecting to the machine running iptables. It does not redirect the port for clients running on the iptables machine trying to connect to port 25570 (for example).

These entries will forward the port for connections coming from the network or from the local host running the services.

sudo iptables -t nat -I PREROUTING -p tcp --dport 443 -j REDIRECT --to-ports 8443
sudo iptables -t nat -I OUTPUT -p tcp -o lo --dport 443 -j REDIRECT --to-ports 8443