ssh connect over ssh tunnel
ssh -o ProxyCommand="ssh -W %h:%p root@jump.example.org" root@target.example.org
or write it to ssh config file
Host xxx
HostName target.example.org
User root
IdentityFile ~/.ssh/id_rsa
ProxyCommand ssh -W %h:%p root@jumphost.example.org
another
ssh -L local_Port:target.example.org:22 root@jumphost.example.org
write it to ssh config file using LocalForward