Example SSH config file.
Host intermediary
User foobar
Hostname 100.100.121.33
Port 14500
ServerAliveInterval 60
ServerAliveCountMax 30
Host target
User foobar
Hostname 100.100.232.44
Port 22
ForwardAgent yes
LocalForward 9000 localhost:80
ProxyCommand ssh -W %h:%p intermediary
ServerAliveInterval 60
ServerAliveCountMax 30