Linux as a router to forward

How to make an OpenStack instance to forward route to another Linux machine which is not OpenStack instance but in the same LAN? PC_A has 192.168.1.133/27. PC_B has 192.168.1.140/27. PC_A has 10.26.14.16/25 route. PC_B has no 10.26.14.16/25 route. I want PC_B to reach 10.26.14.16/25 via PC_A. Note: PC_B is an OpenStack Instance. It's private IP is 192.168.118.10/27 and public IP is 192.168.1.140/27. FW----------PC_A--------------PC_B [192.168.1.133/27] [192.168.1.140/27] Public IP of B [192.168.118.10/27] Private IP of B PC_A has 10.26.14.16/25 route. PC_B has no 10.26.14.16/25 route. I want PC_B to reach 10.26.14.16/25 via PC_A.