Firewall on Netdata

How To Check Your Firewall Logs On Windows

Thu, 01 May 2025 00:00:00 +0000

Every Windows system comes equipped with a built-in firewall, a critical component of its security posture. The Microsoft Defender Firewall (previously Windows Firewall) acts as a gatekeeper, controlling incoming and outgoing network traffic based on predefined rules. While it diligently protects your system, its default configuration doesn’t tell you much about the traffic it’s allowing or blocking.

This is where Windows Firewall logs come in. These logs record detailed information about the firewall’s activity, providing invaluable insights for troubleshooting network connectivity problems, identifying potential security threats, and ensuring compliance. For developers, DevOps engineers, and SREs, knowing how to check firewall logs is a fundamental skill for maintaining secure and reliable Windows environments, whether on workstations or Windows Server instances. This guide will walk you through enabling, locating, interpreting, and managing these essential logs.

License expiry silently disabling features: monitor days-to-expiry

Mon, 01 Jan 0001 00:00:00 +0000

Your firewall dashboard shows green. Interfaces are up, CPU and memory are normal, traffic is flowing. But at 09:00, someone reports VPN connections failing, IPS no longer blocking threats, or URL filtering not enforcing policy. A feature license expired at midnight, and the device silently stopped performing the licensed function without raising a visible alarm.

The device stays up, counters keep incrementing, throughput looks normal. The license-expiry message in syslog is low severity and gets buried under routine noise. By the time someone notices, the feature has been disabled for hours.

NAT and session-table exhaustion: catching it before connections fail

Mon, 01 Jan 0001 00:00:00 +0000

New connections fail while existing ones keep working. Applications report “connection refused” or timeouts. Open SSH sessions stay alive, but new SSH attempts hang. Your monitoring shows the firewall or NAT gateway is up, interfaces are healthy, and CPU is normal. The session or NAT translation table is full.

Session-table exhaustion is a cliff-edge failure. The table degrades gracefully until it hits its limit, then every new connection is denied. Existing flows continue because their entries are already in the table. The symptom pattern is distinctive but easy to misdiagnose as application failure, DNS issues, or upstream provider problems, because the applications are the ones reporting errors.

Redis cluster bus port blocked: the port+10000 firewall gotcha

Mon, 01 Jan 0001 00:00:00 +0000

CLUSTER INFO reports cluster_state:fail. Nodes show non-zero cluster_slots_pfail. Clients receive CLUSTERDOWN. Yet redis-cli -p 6379 PING returns PONG on every node, application connections are still accepted, and the client port shows no obvious network outage. The cluster behaves like it is partitioned, but only the bus is broken. Port 16379, or your configured client port plus 10000, is missing from a firewall rule, security group, or container port mapping. The cluster bus carries gossip, failure detection, and node discovery over this separate TCP port. When the bus is unreachable, nodes cannot synchronize the cluster map, so they mark peers as failed and withdraw slot coverage even though the data port stays healthy. Because firewall rules often cover the client port but omit the bus port, this failure mode is common after infrastructure changes, node replacements, or environment migrations.