New England Data Services Blog

Firewall? Do I Really Need It?

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So there is a pop up saying my firewall is not turned on, does it matter?  Yes.  Firewall is a term taken from firefighting where a firewall is used to prevent the spread of a fire.  Like the original term, a computer firewall is a barrier keeping things such as spyware or malicious software from infecting your computer or spreading the "fire".  It uses a certain criteria or set of rules to distinguish what or who can enter into your network.  Frequently, firewalls are used to exclude unauthorized Internet users from accessing your private network connected to the Internet. 

Firewalls are broken into four types, but depending on which product you use, your firewall can fall beneath more than one if not all.

Network Layers

Network layer firewalls are also known as packet filters and are very fast and transparent to their users.  Traditionally, a router is the network layer firewall.  A router typically could not make complicated decision about what a packet is talking to or where it came from, but now modern network layer firewalls maintain internal information about the state of connections passing through them.  In order to use a router though, you need a validly-assigned IP address block or a private Internet address block.

Application Layer

This type is not as transparent as the Network Layer firewall possibly decreasing performance.  Application layer do provide more detailed audit reports and tend to enforce more conservative security models.  Application layer firewalls are hosts running proxy servers that do not allow traffic between networks by performing elaborate logging and examination of the traffic passing.  These can be used as network address translators as well.

Proxy

A proxy firewall offers more security than the other types, but at the cost of speed and functionality.  With a proxy, traffic does not flow through it.  Computers instead establish a connection with the proxy which acts as the "middleman" and starts a new network connection on behalf of the request.  This prevents direct connections making it difficult for a hacker to find where a network is.  It also provides protocol-aware security analysis for the protocols they support.

Unified Threat Management

This is a valuable type of firewall for small to medium sized businesses.  This guards against intrusion, but also performs content filtering, spam filtering, intrusion detection and anti-virus.  The all-in-one approach reduces complexity and makes troubleshooting an easier process.

So, a firewall is ultimately your friend and bodyguard.  By using one, you can save yourself time and trouble from possible viruses in the future.