You can consider your router the perimeter between those machines you trust and those you don't.  When you port-forward, you are permitting access from machines you don't trust to one that you do.  This automatically lowers the trust of your machine.  This is warranted because when you are port-forwarding you are saying that it is acceptable for a machine that you don't trust to influence the behaviour of one that you do trust, each time a connection is made to it.

While you may only permit access to a specific service on your machine and so influence should be confined to a known quantity (such as serving a web page), there are no guarantees that there are no exploitable vulnerabilities in the application you are allowing to be accessed by external parties.   If a vulnerability exists and is exploited, the worst case is that someone else has control of your machine.  If they have control of your machine, then they can use it as a jumping point to probe other machines in your network for vulnerabilities.

This is why in corporate environments, efforts are made to ensure that any machine that will be directly accessed from the internet is segregated from the rest of the network via firewalls.  This can help limit the ability of an attacker to get further into the network.

So this is the risk you must accept, and help better define the risk, you would need to examine the history of the application being exposed - how frequently critical vulnerabilities are uncovered, and how quickly they are addressed.

Mitigation strategies you can employ are about reducing your exposure.  This can be done by only port-forwarding when you want to use the service, or closing the application when not needed.

Does port forwarding a port on one computer expose other computers in the network as well?
I know about mentioning Jesus died to redeem mankind in evangelical literature like:


  For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. (John 3:16)


But I suspect these are only later interpretations. Has Jesus himself ever said his dead is a sacrifice?

If so, isn't double meaning in Greek? At least in Czech, English and German you could use the phrase "he died for humans' sins" in sense of "because of" - like cause of his death was humans' fault - fault of the Romans who crucified him.

(btw I think I understand the evangelical message so I'm not asking how christians get it today, so please don't make your interpretations of the direct Jesus' quote much distant)

Thank you.
