Recommended Palo Alto Firewall Syslog Configuration

This article provides configuration recommendations for Palo Alto firewalls to ensure consistent and reliable syslog message parsing by your syslog server.

Question

What is the recommended syslog format configuration for Palo Alto firewalls when sending logs to a syslog server?

Answer

We recommend configuring Palo Alto firewalls to use IETF RFC 5424 syslog format instead of BSD

RFC 3164

format. The IETF format provides a structured, unambiguous message format that ensures consistent parsing regardless of Palo Alto firmware version or spacing differences in log messages.

Why Use IETF (RFC 5424) Format?

IETF format is recommended over BSD

RFC 3164

format for the following reasons:

1. Structured format: IETF format includes a required APP-NAME field that eliminates parsing ambiguity

2. Consistent parsing: The structured format ensures your syslog server parses messages consistently regardless of: * Palo Alto firmware version * Spacing differences in log messages * Future firmware updates that may change message formatting

3. Better compatibility: IETF format is the modern syslog standard and provides better support for SIEM systems and log analysis tools

4. Prevents parsing issues: BSD format relies on heuristics that can be affected by spacing changes, potentially causing fields like version= to be parsed incorrectly or missing from output

Note: If you’re experiencing issues where the version= field is missing from syslog output after a Palo Alto upgrade, this is typically caused by BSD format parsing ambiguity due to spacing changes. Switching to IETF format resolves this issue.

Configuration Steps

Step 1: Access Syslog Server Profile

1. Log in to the Palo Alto Networks firewall web interface

2. Navigate to: Device > Server Profiles > Syslog

   Reference: Palo Alto Documentation - Configure Syslog Monitoring

3. Either: * Edit an existing syslog server profile, or * Click Add to create a new profile

Step 2: Configure Syslog Server Settings

For each syslog server in the profile:

1. Name: Enter a unique name for the server (if creating new)

2. Syslog Server: Enter the IP address or FQDN of your syslog server

3. Transport: * Important: IETF format typically uses TCP or SSL (TLS) * Select TCP or SSL (not UDP) * If using SSL, ensure TLSv1.2 is supported

   Reference: Palo Alto Documentation - Configure Syslog Server Profile

4. Port: Enter the port number (default TCP syslog port is 514, but verify with your syslog server configuration)

5. Format: Select IETF (this is the key setting)

   Reference: Palo Alto Documentation - Configure Syslog Server Profile

6. Facility: Select the appropriate syslog facility value (default is LOG_USER)

Step 3: Verify The Syslog Service Supports RFC 5424

Before applying the changes, ensure:

1. The Syslog Service supports RFC 5424 format: Verify that RFC 5424 parsing is enabled

Ensure RFC 5424 parsing is enabled in the Syslog Server service configuration.

Step 4: Commit Configuration

1. Click OK to save the syslog server profile

2. Commit the configuration

3. Review the commit and click Commit again to confirm

   Reference: Palo Alto Documentation - Commit Changes

Step 5: Verify Configuration

After committing:

1. Check syslog messages on your syslog server

2. Verify the format: Messages should now appear in IETF format:

   <14>1 2025-10-30T13:13:04.000Z e26secgw02 paloalto - - [meta version="11.2.6"] version=11.2.6|subtype=general|...

3. Verify APP-NAME field: The paloalto field (APP-NAME) should be present and consistently parsed by your syslog server

4. Verify output format: Syslog server output should now consistently include the version= prefix

Expected Results

After configuring IETF format, you should see:

• Consistent message format: Messages appear in structured IETF format with the APP-NAME field (paloalto) consistently parsed

• Reliable field extraction: All fields, including version=, are reliably extracted regardless of Palo Alto firmware version

• Future-proof configuration: The structured format ensures consistent behavior even after firmware upgrades

• Better log analysis: The structured format provides better support for SIEM systems and log analysis tools

Benefits Summary

Using IETF (RFC 5424) format provides:

• Eliminates parsing ambiguity: The structured format with required APP-NAME field ensures consistent parsing

• Prevents version-related issues: Spacing changes in firmware updates won’t affect message parsing

• Industry standard: IETF format is the modern syslog standard recommended for enterprise environments

• Better integration: Improved compatibility with SIEM systems, log analysis tools, and centralized logging solutions

Technical Reference

• RFC 3164 (BSD)

• RFC 5424 (IETF)

• Palo Alto Documentation - Configure Syslog Monitoring

• Palo Alto Documentation - Syslog Field Descriptions

• Palo Alto Documentation - Use Syslog for Monitoring

Additional Information

For more information about syslog server configuration and RFC 5424 support, see the Syslog Server documentation in your product’s manual.