Connect 2 networks together *Newb*

Networking
1

I have an ubuntu server running 16.04 There are 2 Nic cards. One is 192.168.10.9/24, this has internet access through the gateway of 192.168.10.254. My second Nic card had an ip of 192.168.25.1/24 and currently does not have a gateway or internet access. Everything on the 192.168.25.x network is using DHCPD from the ubuntu server. How do I allow internet access to the 192.168.25.x?

2

Set the server to forward packets:
echo 1 > /proc/sys/net/ipv4/ip_forward
then set the clients on the 192.168.25.X to have the server as the default gateway.

This should work, but the routes or firewall rules on the server may interfere...