Using a firewall is an important part of securing any Linux system. As a Linux user, you want to check on the status of your firewall regularly to make sure it is running properly and blocking unauthorized access.

Don't worry, checking your firewall status is easy once you know a few basic commands!

Why Checking Firewall Status Matters

Having an active firewall protecting your Linux environment is essential these days. Linux firewalls like iptables and firewalld create security rules that filter inbound and outbound network traffic. This protects your system from exploits and unauthorized access that could lead to data breaches or malware.

Regularly verifying your firewall status ensures:

• Existing firewall rules are still active and haven't been accidentally disabled or deleted.

• No vulnerabilities or misconfigurations have crept in over time as your system changes.

• No stealthy malware has tried to disable your firewall without you realizing it.

Catching such issues early prevents problems down the road. So be sure to check in on your firewall periodically.

Also read - How to Install NVIDIA Drivers on Linux Debian

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How to Check iptables Firewall Status

Many Linux servers still rely on iptables as their primary firewall solution. Below are the top methods for verifying iptables is active and configured properly.

1. Check if iptables service is active

bashCopy codesudo systemctl status iptables

• This command displays whether the iptables service is running, gives recent log entries, and shows any errors.

• Look for “active (running)” in the output to confirm it’s working correctly.

2. List current iptables rules

bashCopy codesudo iptables -L

• This shows all chains, rules, priorities, and more.

• Review the list to ensure your expected rules are present and that no suspicious ones have appeared.

• Alternatively, you can use sudo iptables -S for a different listing format.

3. Check iptables logging

bashCopy codesudo less /var/log/messages | grep iptables

• Scans the system logs for iptables activity.

• Reveals blocked or allowed traffic, helping you detect unauthorized connection attempts.

Tip: If you’re using nftables (the successor to iptables), similar checks apply. You can run sudo nft list ruleset to view the current nftables rules.

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How to Check firewalld Status

If you’re running a Red Hat-based system (RHEL, CentOS, Fedora) or other distributions that ship with firewalld, you can manage your firewall dynamically with these commands:

1. Is firewalld running?

bashCopy codesudo systemctl status firewalld

• Confirms whether firewalld is active and lists any recent log messages or errors.

2. List all configured firewall rules

bashCopy codesudo firewall-cmd --list-all-zones

• Shows each zone, the sources, services, and ports allowed in that zone.

• Double-check that these align with your intended security posture.

3. Check the firewalld log

bashCopy codesudo less /var/log/firewalld

• Displays recent inbound and outbound traffic that firewalld has processed or blocked.

• Any unexpected IP addresses or blocked ports here could indicate malicious activity.

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Other Quick Ways to Verify Your Firewall

Sometimes you need a high-level check of your firewall status. Here are a couple of quick tests:

1. UFW Check

    bashCopy codesudo ufw status
   

   • If you’re on Ubuntu or a similar distro, this shows whether UFW is enabled and the current list of rules.

2. Nmap localhost

    bashCopy codenmap localhost
   

   • This runs a local port scan on your machine.

   • Any open ports you weren’t expecting? That might be a sign your firewall rules need adjusting.

3. Port Testing with netcat or telnet

   • From another machine on the network, try:

       bashCopy codenc -zv <server-ip> <port>
     

     or

       bashCopy codetelnet <server-ip> <port>
     

   • If the connection succeeds when it shouldn’t, your firewall might not be blocking the port as intended.

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How to Inspect Your Firewall Logs

Regular log reviews can reveal intrusion attempts, traffic anomalies, and misconfigurations. Depending on distribution and configuration, firewall events typically appear in:

• /var/log/messages (CentOS, Fedora, RHEL)

• /var/log/syslog (Debian, Ubuntu)

• Dedicated files like /var/log/firewalld

Use commands like:

bashCopy codesudo grep "BLOCK" /var/log/syslog

or

bashCopy codesudo grep "REJECT" /var/log/messages

to quickly find critical firewall actions.

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Linux Firewall Best Practices

1. Enable Only One Firewall Service – Avoid conflicts by ensuring you’re only running iptables or firewalld (or UFW), not multiple frameworks simultaneously.

2. Restrict Unused Ports – Disable or block every port you’re not actively using.

3. Implement Logging & Alerts – Enable detailed logging and set up alerts for repeated blocked requests.

4. Regular Audits – Periodically check for new or removed rules that might compromise security.

5. Backup Your Rules – Always keep a backup of your working rules before making changes.

By regularly auditing and reviewing logs, you’ll detect stealthy changes before they become major vulnerabilities.

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Firewall Policy Manager for Ongoing Security

A set-and-forget approach to firewalls rarely works over the long term. As your system expands with more apps and services, your firewall rules should evolve, too.

If you need a robust way to monitor and refine your policies at scale, consider a Firewall Policy Manager like FireMon. Tools like this allow you to:

• Visualize firewall rules and identify duplicates or conflicts.

• Automate policy compliance for regulatory requirements.

• Simplify rule management across multiple Linux servers or hybrid environments.

Conclusion

Maintaining a secure Linux environment starts with knowing that your firewall is active and properly configured. By regularly checking the status of iptables, firewalld, or UFW—and diligently reviewing the logs—you’ll stay ahead of malicious actors trying to breach your system.

Key Takeaways:

• Verify your firewall’s active status with systemctl status commands.

• List firewall rules (iptables -L, firewall-cmd --list-all-zones, or ufw status) to ensure everything is correct.

• Inspect your logs frequently for suspicious activity.

• Adopt best practices like restricting unused ports and running only one firewall service.

• Consider using a firewall policy manager for ongoing rule maintenance at scale.

With regular checks and a proactive approach, you can uphold robust Linux firewall protection in 2025 and beyond, safeguarding your system against evolving threats.