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Best practices for firewall logging

May 24, 2023 6 min read

A firewall is used to monitor and filter traffic that enters and exits a network, based on a set of predetermined rules or policies. Enabling firewall logging is thus crucial for getting visibility into network traffic. Firewall logging pertains to the process of collecting, analyzing, verifying, and auditing events to spot threats to network security. By analyzing firewall logs, security administrators can detect an attack at the intrusion stage itself.

How firewall logging helps ensure safety for your network:

Bad actors may use your network as a launching pad of sorts for attacks on other networks. Firewalls monitor outgoing traffic as well as attacks that originate from within your network. There also may be instances where you see multiple attacks originate from the same IP address. Good firewall logging practices will help identify and alert you about any security incident before it becomes a full-scale attack. For instance, repeated failed attempts to log in to your organization's network can be indicative of such attacks, something firewall logging practices will immediately pick up on.

Here are some of the best practices that your organization can follow to guarantee your firewall logging is effective.

Know what to log

Understanding important security events and how they may constitute a larger attack on your organization is the backbone of firewall logging. Incorrect password entries, unsecured connections, and requests from blacklisted or suspicious sources will help in detecting cyberattacks. Apart from this, all events that may be indicative of a potential threat or attack need to be logged. Accurately logging events is a crucial step to ensuring effective logging practices. An example of events that are usually logged include:

  • Connections permitted or denied by firewall rules
  • Intrusion detection activity
  • User activity
  • Cut-through-proxy activity
  • Protocol usage

Secure firewall log storage

When logging is enabled in a firewall, the logs get stored locally. To make the best use of the firewall logs, they should be stored and analyzed in a central server. Moving the logs away from the firewall to a more secure location prevents bad actors from tampering with them, improves logging efficiency, and ensures maximum safety and protection.

Centralized firewall logging

Once all the logs have been collected and moved to a secure storage location, it is imperative to perform logging activities like parsing and indexing to provide a uniform structure to logs collected from different sources. This will ensure that the collected logs are monitored and analyzed to provide insights into network activity, and will secure your organization's network from threats.

Correlate and understand different firewall events

Network activity, when looked at as isolated events, may be harmless, but as a whole it may be indicative of a larger threat to your network security. Correlation pertains to the process of understanding the connection between events that happen discretely in different devices of the network. Once all the logs from different sources are collected, indexed, and parsed in a central server, it's easier to correlate those logs.

Track rule changes in firewalls

A firewall is essentially a set of rules that define which devices can access the network and communicate with the other devices on that network. If there is a change in the protocols that decide whether a connection request must be accepted or denied, it must be logged. This ensures that if the change was made by a bad actor or by a malicious insider, there will be traceability. Ideally, the system administrator should be notified or alerted in the event of any changes to the rules of a firewall.

Implement a logging tool

Performing logging activities manually on the collected logs is a very time-consuming task that is prone to human error. The best way to ensure efficiency and efficacy is to implement a logging tool to automate the logging process. If there is any suspicious activity that a logging tool spots, the security administrator will immediately be notified through an alerting system. These logs will provide important information regarding traffic, its origin, its destination, the port addresses, and other critical details so that threats can be identified before they occur, and attacks can be investigated. EventLog Analyzer is a comprehensive log management solution that can collect, process, analyze, and correlate firewall logs in a central server.

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