Bridge

Install tools

Depending on your OS, install:

 sudo apt install bridge-utils
 sudo zypper install bridge-utils

Edit config

Depending on your OS, call:

 sudo vi /etc/sysconfig/network-scripts/ifcfg-br0
 sudo vi /etc/sysconfig/network/ifcfg-br0

Contents should look like

 DEVICE=br0
 TYPE=Bridge
 IPADDR='192.168.178.11/24'
 BOOTPROTO='static'
 ONBOOT=yes
 STARTMODE='auto'
 ZONE=public
 BRIDGE='yes'
 BRIDGE_PORTS='eth0'
 BRIDGE_STP='off'
 BRIDGE_FORWARDDELAY='15'
 GATEWAY=192.168.178.1
 NETMASK=255.255.255.0

Note that this is a bridge, not a router. So the IP addresses of one side of the bridge must be in the same subnet as on the other side.