A firewall, when properly configured, blocks access to your computers from outside sources. However it will still let you browse the Internet, do your on-line banking, and whatever else you need to do.
Most routers and modems that connect to the Internet have a built-in firewall. This may be the best place for your firewall, in that access attempts are blocked before they get to your computer. So they do not add any load to your system. However, if your firewall is on your router/modem, make sure that you have access to it.
Many service providers will install this hardware, and not give you access to change the configuration. If this is the case, it is better to have them turn off the firewall, and move the firewall function to your system. By having access to your firewall configuration, you can tune it to meet your needs. One of the biggest points being, you can allow access to your system for support purposes.
Whether your system is Windows, or UNIX/Linux, it has the ability for outside support to connect, and troubleshoot your system. This is to your advantage, in that help is immediately available, instead of having to schedule a time, and have someone dispatched to your site. This outside access is almost always blocked in a standard installation.
We have a great deal of experience with configuring firewalls to allow support access, but still be safeguarded from hack attempts in general, and are happy to help you. Contact CCS Retail Support to schedule an appointment.