Example 1

Connect to a host that it is not in your network via said host’s gateway

from:   local machine (192.168.122.1)
to:     10.10.10.3
via:    gateway (192.168.122.77 | 10.10.10.1)

user@local: ssh -L 22003:10.10.10.3:22 user2@192.168.22.77 # connects to gateway
user@local: ssh -p 22003 user2@localhost                   # connects to 10.10.10.3

Example 2

Connect to PostgreSQL in a host in your network

from:   local machine (192.168.1.126)
to:     192.168.1.196
via:    local machine (192.168.1.126 | localhost)

user@local: ssh -L 5555:localhost:5432 root@192.168.1.196

Example 3

Connect to a web page at port 8443 in a host in your network

from:   local machine (192.168.1.126)
to:     192.168.1.193
via:    local machine (192.168.1.126 | localhost)

user@local: ssh -L 8000:localhost:8443 root@192.168.1.193

Going to http://127.0.0.1:8000 will take you to http://192.168.1.193:8443.

Example 4

Connect to a host that is not in your network via another host that is not in your network either

from:   local machine (192.168.1.126)
to:     devops1 (82.223.1.1)
via:    proxy (82.223.1.2)

user@local: ssh -A -t proxy ssh -A -t devops1

Or:

.ssh/config:
------------
Host proxy
    Hostname 82.223.1.1

Host devops1_tun
    ProxyCommand ssh -W %h:%p user@proxy