“Meet in the middle” with SSH

machineA = home
serverB = Middle (Real IP)
machineC = work

I am machineA. I want connect machineC port 22

Machine C
ssh -R 10022:localhost:22 user@serverB
= open port 10022 on B. it mapped to machineC port 22

Machine A
ssh -L 10022:locahost:10022 user@serverB
= open localhost port 10022 mapped to serverB port 10022

To connect machineC port 22
= ssh localhost -p 10022