Syslog

Syslog

Network Log Analyser

Syslog

Collect and analyse Syslog messages from network devices, servers, and appliances in real time. Cloudmon receives forwarded Syslogs on port 514, applies configurable log rules to filter and act on messages, and surfaces insights through an AI-assisted analysis engine.

Overview

Syslog is a widely used standard for forwarding event messages from network devices, operating systems, and applications to a central collector. Cloudmon acts as the Syslog receiver, collecting messages forwarded from your devices on port 514 and making them available for analysis, filtering, and alerting under Logs → Syslogs.

Once Syslog monitoring is enabled, Cloudmon processes incoming messages in real time. Log rules can be applied to tag specific entries for easy filtering, discard irrelevant messages before they reach the database, create events for significant log entries, or raise alarms when specific conditions are matched. This gives your team full control over signal-to-noise ratio without losing visibility into critical events.

Configuration

Syslog monitoring is enabled at the probe level, since it is the probe that listens for incoming Syslog messages from devices in its network segment. There are two ways to enable it:

  • Via Probe Settings: Navigate to Settings → Monitoring → Probes, select and edit the probe where Syslog monitoring needs to be enabled, and activate the Syslog monitoring toggle.
  • Via Network Device: Navigate to Network → Network Devices, select and edit the specific device, and enable Syslog monitoring at the device level.

After enabling Syslog monitoring, configure your network devices to forward Syslog messages to the Cloudmon probe on port 514. This is done on each device through its Syslog or logging configuration. Once forwarding is active, messages will appear under Logs → Syslogs.

Log Rules

Log rules let you control how Cloudmon processes incoming Syslog messages before they reach the database or trigger alerts. Navigate to Settings → Configurations → Log Rules and click Add to create a new rule. Fill in the fields as follows:

FieldDescription
EnabledDetermines whether the rule is active. Set to Off to disable the rule without deleting it.
NameA descriptive name for the rule that identifies its purpose, such as "Flag Critical Firewall Events" or "Discard SNMP Noise".
ProbeThe probe to which this rule applies. Rules are scoped per probe, so a rule created for one probe will not affect Syslogs received by another.
Log TypeSet to Syslog to apply this rule to incoming Syslog messages.
ConditionsDefines whether the rule applies to every Syslog entry or only to entries that match specific criteria such as severity level, message content, or source device.
Active Time WindowRestricts the rule to a specific time window. Useful for suppressing low-priority alerts during maintenance windows or off-hours.
Entry CountControls whether the rule fires for every matching log entry or only after a specific count is reached.
FloodWhen enabled, removes any cooldown period between rule triggers, allowing the rule to fire continuously for every matching entry.

Each rule also includes an Actions section where you define what Cloudmon does when the rule conditions are matched:

ActionDescription
Tag the EntryApplies a custom tag to the log entry. Tags can be used in later rules, searches, and dashboard visualisations to organise and categorise Syslog data. For example, tagging all entries from a specific firewall with "security-critical" makes them easy to filter.
Flag for DiscardMarks the entry as discarded so it is not saved to the database, while allowing subsequent rules to continue processing. Use this to suppress high-volume informational messages from chatty devices like UPS systems or printers.
Stop Processing RulesStops any further rules from being applied to this log entry once the current rule matches. Useful when a discard rule should prevent downstream alert rules from firing on the same entry.
Create Event for the LogGenerates a Cloudmon event record based on the matching log entry, making it available for tracking and audit without requiring a full alarm.
Raise AlarmsTriggers a Cloudmon alarm whenever the rule conditions are met. Use this for Syslog severity levels 0 to 3 (Emergency, Alert, Critical, Error) from network devices to ensure critical events always surface as alarms.

Click Save to apply the rule. Rules are evaluated in order for each incoming Syslog message.

Assistive AI for Syslog Analysis

Cloudmon integrates with Azure OpenAI to provide AI-assisted analysis of Syslog entries. When viewing a Syslog message under Logs → Syslogs, click the AI button next to the entry to trigger analysis. Cloudmon returns a structured breakdown covering an Overview of the event, its potential Impact, a plain-language Summary, and Troubleshoot and Analyse guidance, helping your team understand and respond to complex log messages without needing to look up device-specific documentation.

For example, a cryptic firewall Syslog message about an interface state change or a routing protocol adjacency loss can be decoded instantly into a clear explanation of what happened, what service may be affected, and what to investigate next.

To enable this feature, an Azure OpenAI integration must be configured under Settings → Configurations → Integrations. Enter your Target URI and API Key from your Azure OpenAI resource and click Save.

Troubleshooting

IssueWhat to check
No Syslogs appearing under Logs even after enablingConfirm Syslog monitoring is enabled at the probe level under Settings → Monitoring → Probes. Then verify the network device is configured to forward Syslog messages to the probe IP address on UDP port 514. Check that no firewall is blocking UDP 514 between the device and the probe.
Syslogs are arriving but from wrong or unknown sourceThe source IP in the Syslog message may differ from the device's management IP if the device is sending Syslogs from a loopback or a different interface. Configure the Syslog source interface on the device to match the IP address used in Cloudmon for that device.
Log rule is not tagging or discarding entries as expectedCheck that the rule is set to Enabled and that the Log Type is set to Syslog. Verify the Conditions section matches the actual content or severity of the incoming messages. If a Stop Processing Rules action is configured in a previous rule, the current rule may never be reached for matching entries.
Too many Syslog entries filling the databaseCreate a log rule with the Flag for Discard action to filter out high-volume, low-value messages such as routine informational messages from UPS systems, printers, or SNMP polling acknowledgements. Pair it with a Stop Processing Rules action to prevent the discarded entries from triggering any downstream rules.
AI analysis button not visible on log entriesThe Assistive AI feature requires an Azure OpenAI integration to be configured. Navigate to Settings → Configurations → Integrations, locate the Azure OpenAI Service widget, and confirm a Target URI and API Key have been saved. If the integration is missing, the AI button will not appear next to log entries.
    • Related Articles

    • To use Cloudmon's Syslog feature, do we need an external Syslog server?

      No, we do not need an external server to maintain the System logs. Enabling syslogs in the network device will be sufficient. 
    • Can Cloudmon alert users about threats in a device?

      Yes, you can configure SNMP trap or syslog alerts for specific messages, log types, or a certain count of logs in a given interval to notify users of potential threats.
    • Can i send all syslogs from devices and monitor at a common place?

      Yes, Cloudmon collects Syslogs from the devices, and they can be monitored from a single Cloudmon controller.
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