Would a VPN prevent hackers from gaining access to my network if already breached?

Question

Hypothetically, if someone had illegal access to your network, wireless, or the like, and if you set up a VPN, would that stop the hacker from being able to see everything that you do or would him having prior access to the network trump the VPN setup?

Also, if I do setup a VPN, what protections does it give me as far as keeping people from accessing my email, what I do online, being able to convos through our phones, etc?

As an added security, is the general consensus to use something like a Tor browser or setup (not sure what the technical terms are) along with using a VPN?

Basically, I just want to take steps to the point of overkill to protect my network and any device that is using it as well.

EDIT

Thank you to whomever provided that information about the duplicate question, I looked at it and it was pretty much what I needed, but I think I needed a simpler answer to my question, as I don't know a lot of technical jargon. I did also want to know how Tor and VPN works in as close to layman's terms as possible and the commenters did a great job of helping explain that.

Answer 1

A VPN does not magically protect a network. Contrary - it opens yet another way into the network. A VPN can only increase security if it is used instead and not in addition of the previous more open access, i.e. if you deny any access from outside except authorized access using the VPN.

But even then a VPN will not magically fix a breached network. If the attacker is already inside the network a VPN will not remove the malware or backdoors he might planted in the network. At most a VPN will prevent the attacker easy access into the network. But likely even this will not be prevented: if anybody can send data out of the network the attacker can to and this way also create a tunnel from the inside to the outside which then can be used to get back into the network.

Additionally a VPN offers another path into the network. If the external VPN endpoint is an insecure system then an attacker might infiltrate this external system and use an established VPN connection from this system to get back into the network.

Also, if I do setup a VPN, what protections does it give me as far as keeping people from accessing my email, what I do online, being able to convos through our phones, etc?

It depends where the endpoints of the VPN are. If you only use some VPN with an external endpoint to protect your communication against your ISP then it will do exactly that, and only that. It does not provide any additional protection from the VPN endpoint to the mail server, web sites you visit etc. And the same is true with Tor: it does not protect the traffic to the final endpoint of the communication but only to the Tor exit node. Additionally no VPN will you protect you against phishing attacks or similar where others steal your credentials for mail and then can access your mail, no matter if you use a VPN or not.

Basically, I just want to take steps to the point of overkill to protect my network and any device that is using it as well.

VPN is not a generic network protection tool. It's goal is only protect the communication between the two VPN endpoints against sniffing and modifying. When used together with authentication it can restrict who can access the network from outside - but only if the VPN is the only way into the network.

Answer 2

Think of a VPN like a tunnel. You tunnel underground, out of your house, past a dangerous area and then out into a more trusted area. (A gross over-simplification)

Would digging this tunnel do anything to eject a squatter in your property? No. The squatter gained access and has their own methods in an out. To deal with the squatter, you need to identify it and how they got in and close the route into your home.

Tor helps to protect your anonymity when you browse. It does not protect your phone.

You appear to be looking for a single protection measure to deal with what you think is a widespread weakness across your computers, your network, your landline and your car (from your previous question). Complex problems do not have simplistic solutions. You need to get to the root of the problem, not throw technology at it.