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Firewalls are crucial in securing networks and keeping digital threats outside of them.
By acting as a security guard that always watches over the network traffic and keeps the bad actors out of the network, firewalls are considered one of the best tools against cyber criminals.
You probably already know what a firewall does, but do you know about firewall logs?
In this guide, we aim to help you learn more about firewall logs, basically the detailed records of all network activities, by explaining it so that even non-techies can grasp it.
This guide lets you understand these logs’ importance and value in fortifying your network against cyberattacks.
What are Firewall Logs? A Simple Explanation
Firewall logs are simply comprehensive records about the network traffic monitored by the firewall, and they include vital information for insights and better security.
They are similar to detailed diaries with the history of every interaction between a network and the outside Internet.
So how does a firewall work? This is important to understand how the logs are created.
First, whenever data packets want to enter a private network, firewalls evaluate it based on the rules determined by the administrators and decide whether it is allowed.
Once this interaction happens, all the information about this attempt is saved in firewall logs. Logs usually have the IP addresses, port numbers, and the action taken by the firewall.
Reviewing firewall logs and analyzing the actions taken in these interactions are critical for network administrators to identify potential vulnerabilities and see the overall security posture of their networks.
These logs are like breadcrumbs that professionals can use to track back a potential attack or emerging threats.
Common Terminology in Firewall Logs
Now that we know what a firewall log is let’s see what terms are used in this field so you understand it better when you hear something about this practice. Some of the common terminology include;
Source/Destination IP Address: Source IP addresses belong to the data packets or users trying to communicate with your network, while the destination IP address is one of the intended recipients.
Port Number: A numerical identifier assigned to different network services on a specific IP address.
Protocol: It refers to the communication protocol used by the network packet, such as TCP (Transmission Control Protocol).
Action: Used to define what the firewall did when it came across a data package. Firewalls can either deny or allow it to go through the network traffic.
Connection/Event Timestamp: The date and time of the specific event logged by the firewall.
Attack Signatures: Certain patterns and signs that shows a potential cyberattack; firewalls use these to detect and respond to security incidents.
Knowing these terms will give you more insights into your firewall logs and help you understand everything in your network.
How to Read a Firewall Log: Step-by-Step Guide
Reading a firewall log may seem highly complex for a non-techy, but dividing the process into a few steps gets much easier. Here is a small guide for you:
#1 Understanding the Log Format
Firewall logs can come in different variations in terms of format.
For example, they can simply be plain text, but they can also be written in comma-separated values (CSV). You need to know different formats to understand them.
#2 Reviewing the Header
The log’s header is essential to understand the initial information about the log, such as the time range and the firewall’s identity. Checking the header information first will help you understand the context better.
#3 Examining Each Entry
This step allows you to analyze every little detail about the interaction. Check key fields such as port numbers, IP addresses, time stamps, and the action taken by the firewall.
#4 Interpreting Actions
Check your firewall’s actions, but especially pay attention to denied entries.
These will indicate potential threats and unfriendly sources. Check the source IP addresses and the port numbers to gain insights about the risks.
#5 Identifying Patterns
Finally, look for common patterns in the access attempts, and compare the source IP addresses to see if you have too many attempts from a single source.
These usually indicate a brute force attack. Patterns will help also help you identify other threats.
Identifying Unusual Activities in Firewall Logs
Each network has its own “normal” in terms of activities. But some common signs indicate potential web security breaches.
The first two things to look for are unfamiliar source IP addresses and unusual destination ports, which may signify an unauthorized access attempt.
Other activities to look for are instant spikes in traffic, repetitive access attempts by unknown sources, and abnormal data transfer values, as these usually indicate a DDoS attack.
But other than these, you need to be able to identify when something does not fit with the usual activities in your network.
Understanding the Role of Firewall Logs in Incident Response
Firewall logs are critical in incident response as they provide valuable insights about emerging threats and potential incidents that admins don’t know yet.
First, firewall logs enable real-time threat detection by recording all the activities.
They also help after an incident by letting IT teams find the root cause of an attack. They can trace the path of the attack using firewall logs and then implement patches to prevent it in the future.
Additionally, firewall logs are great for compliance requirements when an incident occurs.
They can be used as legal evidence of a cyber attack to support investigations, identify the attackers, or build a case for prosecution.
Practical Tips for Managing and Reviewing Firewall Logs
We gathered practical tips for managing firewall logs to detect threats properly beforehand. Here is the list of best practices for reviewing firewall logs:
- Utilize automated tools to review firewall logs in real-time. They will save you time and resources when identifying patterns.
- Set log retention policies according to security regulations and organization policies. This will facilitate historical analysis of security incidents.
- Make sure to monitor user activities as well. Some threats are internal, and the logs from internal access attempts may provide insights into internal risks.
- Set up alarms for unusual activities or suspicious attempts in firewall logs. This will ensure that your incident response team is notified immediately.
- Make sure to train your IT teams on how to analyze firewall logs properly and how to respond to a security incident. Expertise is a must to make use of firewall logs.
Conclusion: Empowering Yourself with Firewall Log Knowledge
Firewall logs are essential resources when it comes to detecting threats and unauthorized access attempts to your network.
While firewalls do a great job of preventing any external attack, IT personnel needs insights from the logs to fix vulnerabilities and improve the overall security posture.
The good thing is firewall logs can be understood and analyzed even by non-techies with simple steps. Understanding these processes will empower you to protect a private network against cyber risks.
