Quite a simple one:
ssh -f USER@INTERMEDIATE_DEVICE -L LOCAL_PORT:DESTINATION_DEVICE:DESTINATION_PORT -N
-f tells ssh to go to background -L binds a local port to a remote device and port -N tells ssh not to execute any commands
So use this to tunnel from local port 8000 in to a remote machine on port 22 you’d use
ssh -f firstname.lastname@example.org -L 8000:server.destination.com:22 -N
Once the tunnel is open you can use the following to ssh or scp data around
ssh localhost -p 8000
scp -P 8000 /path/to/local/file user@localhost:~
scp -P 8000 user@localhost:/path/to/remote/file .
I use ssh tunnels all the time to remote access and use one of our Solr servers that is blocked behind a firewall.