Understanding Firewalls

Understanding firewalls and why you need to protect your IT network

Firewalls in IT are a barrier blocking unauthorised access to a network or device, and the firewall is set according to rules that are set up. Firewalls affect the way networks and devices connected to the internet are protected against viruses, spam and unwanted data which will disrupt and even destroy network information, emails and data. Firewalls are software programs or hardware created with a purpose. To stop transfer of malware, viruses, worms . Unfortunately, this can sometimes cause your computer to work sloooowwly…… and can even clash with some of the software. Emails between different hosting providers can be problematic with their firewalls blocking each other. Firewalls are essential in preventing data fraud

Firewalls come in different forms:

  • Hardware – as a device that acts as a filter
  • Software installed on the network or device.
  • Installation of firewall software can be automatic installation when you purchase a computer,
  • Downloading them off the internet
  • Purchasing them according to need

To know which firewalls are appropriate for your needs, it is better to have specialist help, to prevent slowing down and clashes, but to still protect your network against malware (malicious software)

How does a firewall work?

Firewalls filter data coming through the device or program, blocking certain IP addresses, keywords, or information identified as potentially harmful. Firewalls have developed to a high standard, and is continually being updated as the hacking changes. The software can identify intent of computer instructions (up to a point). Firewalls can also look for known patterns previously experienced and implement a set of instructions to combat this information. Some look more intently at the content, others look st where the content is coming from.

Different types of Firewalls:

Packet filtering firewalls – the original firewall, functioning at junction points of routers and switches.  The firewall compares packets according to set criteria. This means that port numbers, IP addresses and packet types not following the criteria are removed.
Circuit – level gateways – Legitimate content is identified between trusted hosts and untrusted hosts, local and remote hosts. Although circuit – level gateways do not inspect the packets themselves but identify malicious content according to TCP handshakes, legitimate and illegitimate content is identified.
Application level gateways – A proxy firewall which filters packets and other characteristics such as HTTP request strings.
Stateful inspection firewall – this firewall monitors packet filtering, as well as the transaction flow across connection layers.
Dynamic firewalls – this includes deep packet inspection and stateful inspection. Deep packet inspection could track web browsing progress, identifying legitimate HTML responses. Dynamic firewalls can differentiate between new and old connections and has the lowest negative impact on network performance


Firewalls are very necessary, and need to be the type that is needed for your needs. A firewall that is weak can be worse than having no firewall, as you think you are safe, allowing unsafe content to creep in unnoticed.

Firewalls can cause interference with emails because this is an access point for malware, and this needs to be configured by the service provider and professional.

Not having a firewall could cost you all your data, and get leaked to your colleagues

Firewalls protect attacks from the outside. For confidential data, protective measures need to be added from the inside as well eg. USB carrying viruses, Trojans, worms spyware which are added straight into the system.