2. Connection redirected from internal service X to external ssh server Y

Scenario 2.
Destination nat: internal host A connects to internal host B but gets redirected to external Y.

192.168.0.2->192.168.0.1 20025 becomes 192.168.0.2->158.110.144.168

Internal host 192.168.0.2 wants to connect to 192.168.0.1, port 20025 The gateway 192.168.0.1, redirects connection towards 158.110.144.168, port 22. Gateway's work is transparent to 192.168.0.2, who communicates to 158.110.144.168 thinking it is 192.168.0.1.

In the picture above, you can see what happens in IPFIRE nat filter gateway.

Scenario 2. Destination nat: internal host A connects to internal host B but gets redirected to external Y.

Scenario 2.
Destination nat: internal host A connects to internal host B but gets redirected to external Y.