SSH through jump server

ssh_config

#ssh_config
#use with ssh -F ssh_config user@<TARGET_SERVER_IP>
Host *
    ServerAliveInterval    60
    TCPKeepAlive           yes
    ProxyCommand           ssh -q -A gmasgras@<JUMP_SERVER_IP> nc %h %p
    ControlMaster          auto
    ControlPath            ~/.ssh/mux-%r@%h:%p
    ControlPersist         8h
    User                   ubuntu
    StrictHostKeyChecking  no