A beginner’s guide to firewalls

A beginner’s guide to firewalls

Thursday, 21 March, 2019

Despite their dynamic name, firewalls are a mundane yet essential element of online security.

They sit between domestic networks and the internet, acting as gatekeepers by monitoring everything that passes along your broadband connection in either direction.

Their primary role is to identify and block harmful data before it reaches individual devices, preventing them being taken over or corrupted.

However, they also stop unauthorised network traffic flowing out if a device is compromised.

How does a firewall work?

In essence, it scans online data and blocks anything it perceives to be malicious or suspicious.

Its main role is to protect individual networks against the malicious threats that are constantly evolving in cyberspace.

These are identified in various ways, including from source IP addresses or specific code fragments.

There are two distinct types:

  • Hardware – either a standalone appliance, or integrated into the routers and servers used to channel online content into our homes
  • Software – available as a standalone utility, or built into third-party programs like Windows 10.

The former are intended to block access to devices from outwith a local network.

The latter are primarily used to stop information being distributed to the wider world, which often happens through keystroke logging or hard drive hacking.

Both act like digital security guards – unseen in normal circumstances, yet ready to defuse potential threats.

Why are firewalls beneficial?

Simply put, because they minimise certain risks, including the following:

  1. Spyware. If a criminal gains access to your network, or even an individual device, they could acquire personal information and then commit identity fraud or theft.
  2. Ransomware. Users are prevented from using hijacked devices by software that’s unlocked once a ransom is paid. Even then, many systems remain compromised.
  3. Botnets. Devices are harnessed into gigantic online networks. These are used to spread malware or flood network servers with service requests, forcing them offline.
  4. Viruses. Although antivirus software now protects against all the threats listed above, it initially focused on relatively meaningless viruses designed to corrupt or delete data.
  5. Collectively, these threats are known as malicious software, or malware.

Are firewalls difficult to install or maintain?

From operating systems to broadband routers, many devices already have firewalls integrated and turned on by default.

Check the specifications of your hardware devices (in particular desktop computers and WiFi routers) to see if you’re already protected.

If not, it might be worth investing in either a standalone appliance (often costing less than £100), or a software solution.

An old PC could become a router with its hard drive wiped and the Linux operating system installed. Linux is more impervious to attack than Windows.

Finally, install antivirus software on desktop computers for belt-and-braces protection.

PCs are especially prone to malware attacks, though Apple’s OS X operating system is increasing being targeted as well.

Neil Cumins author picture


Neil is our resident tech expert. He's written guides on loads of broadband head-scratchers and is determined to solve all your technology problems!