As part of your network and data security, you must install a firewall of some sort on your system. This is a crucial part of any network or computer system that should help block unauthorized access without stopping outside communication. Creating the firewall must be done with care to ensure that it is secure. You will also need to follow best practices for managing a firewall in the future.
The Best Practices for Managing a Firewall
Document and Explain the Rules
Not everyone in your team will be aware of the details of how a firewall functions or why various rules that make up the firewall are necessary. This is completely normal but can pose a challenge, as users may feel they can skip a specific firewall-related rule if they do not understand it. To ensure that everyone in your organization understands the rules of the firewall and why they are in place, document everything as you configure it.
Every rule should have as much detail as necessary to clearly lay it out. Additionally, you should add a detailed comment that explains why the rule exists, what service it applies to, who will be affected by it, when the rule was added, if the rule is temporary or has a time limit, and who added the rule. This last part of the comment will let future administrators get more information about the rule if necessary.
Deny All Before Adding Exceptions
From a security standpoint, your best option when creating a firewall is to make a “Deny All” rule as the very first one. By prioritizing this as the most important rule, you let the system know that the most important thing is to keep out everything and everyone unless they are specifically given access. Once this rule is in place, continue to add rules to give access back to certain types of traffic.
Create a Request System with an Approval Process
During your configuration of the firewall, ensure that you set it up so that there is an official request system in place for any suggested changes to the system. You do not want to rely on a combination of emails, voicemails, and verbal requests for firewall changes, as these can be challenging to keep track of, making them hard to remember about and take care of in a timely manner. You can easily avoid this by creating an official channel for firewall requests.
This will not only assist with organization and the prioritization of requests, but it will also confirm that no individual makes overly frequent requests. To make the request system even more secure and prevent abuse of the system or requests for changes that are unsafe, consider an approval system for every request. Essentially, you want to make sure that the security or IT department approves the requests so you do not inadvertently leave your network open to a security risk.
Consider Automation for Settings Updates
Once you have established your procedure for making changes to the firewall, you need to ensure that you follow through with it. One of the simplest ways to do this is by using an automation solution. This will also prevent human-error that can lead to a vulnerability that would not otherwise exist.
Let Users Know Before Making Changes to Firewall Rules
Whether or not you use automation to make updates and changes to your firewall settings, you should make it a point to inform users and administrators about these changes ahead of time. Even something that seems like a minor adjustment on your end could lead to a major difference in terms of connectivity. Ideally, you will inform admins and users of the changes far enough in advance so that they have time to voice their concerns, if any, and your team can take a closer look to determine if those concerns are founded and whether the changes should continue as planned.
Use a Backup Firewall
Ideally, your firewall will never fail, but the world is not perfect, and mistakes or emergencies do happen. If your firewall were to fail and you do not have a backup one in place, your network would temporarily be without protection. Because of this, you should always use a backup firewall in addition to the main one, so your backup firewall can take over if the first one has connectivity or other issues. This backup firewall does not need to be active all the time. Instead, it should be set up so that it activates automatically after a given period of time with a failure from the first firewall.
You may also want to consider using several types of firewalls simultaneously to provide multiple layers of security. There are application-based firewalls, endpoint firewalls, and perimeter firewalls. While you could just use one of these, it is also possible to combine them for additional protection. Just be aware that this will require more effort, and you must check for any conflicts in rules or related problems that could negatively impact the network performance.
Regularly Review the Rules
Every once in a while, you should take the time to go through your firewall rules and review whether all of them are still necessary. If you have more rules in the firewall, the performance will slow down, particularly if they are complex in nature. Avoid this issue by removing any rules that are no longer required, such as those related to servers that are no longer within your organization.
Audit Firewall Logs
In addition to reviewing the rules of the firewall, take the time to regularly audit the logs on a regular basis. Look specifically for any anomalies or changes that can indicate that someone modified your firewall. It can also let you know which firewall rules are actually being used and which may not be necessary to have in place.
Consider Deep Packet Inspection
Depending on your organization or business, you may also want to consider adding deep packet inspection to your firewall. Simpler firewalls let data packets through even if they have falsified destination and origin tags. Firewalls with deep packet inspection actually look at what is inside the data packet to confirm it is safe before they let it through the firewall. Deep packet inspection improves the safety and effectiveness of your firewall, and there are levels of inspection.