Your computer network needs to be isolated from the internet. Computers with sensitive information – like financial account numbers and Social Security Numbers – need to be isolated from the rest of the network. Only employees with a need to access non-public Information should have access to it. Firewalls and Routers are the devices that separate your information from the people who want to steal it.
Think of a firewall as a locked door and only the people with a key are allowed to enter through the door. Think of a router as the security guard who determines which rooms can be accessed. Firewalls and routers have rules – access controls – that need to be set, so it knows who and what can enter and go where in your network. For the best protection you want an Application-layer firewall. Their function is to determine if a process should accept a connection. (That’s a little too deep for most of us. That’s why you need to hire an expert.) If the access control rules are not setup correctly either the bad guys can get in or the good guys are kept out. Neither is good.
Above all else, ‘Change the factory default login and password’ and make sure the password is strong – 8 characters or longer with upper and lower case letters, numbers and special characters.
Do not go cheap on the door into your network and lock the door.