Here’s a helpful overview and reference “paper” (structured guide) regarding pfSense serial numbers — what they are, where to find them, how they’re used, and why they matter.
Understanding pfSense Serial Numbers: A Technical Guide 1. What is a pfSense Serial Number? In pfSense software, a serial number is a unique identifier automatically generated during installation. It is not a license key or hardware ID (unless running on official Netgate hardware, where the device’s serial number may be used).
Software (CE – Community Edition) installation : A random 16-character hex string (e.g., a1b2c3d4e5f67890 ). Netgate hardware (Plus) : The hardware’s actual chassis serial number (e.g., NG-12345XYZ ).
2. Where to Find the Serial Number | Method | Steps | |--------|-------| | WebGUI | System > General Setup → Look for “Serial Number” field (read‑only) | | Dashboard | System > Dashboard → System Information widget shows “Serial Number” | | Console / SSH | Run pfSense-upgrade -d or cat /etc/version (some versions) | | Shell command (Unix) | sqlite3 /conf/config.xml "SELECT value FROM system WHERE attribute='serial';" | | Backup file | Inspect /conf/config.xml – search for <serial> tag | 3. Common Uses of the Serial Number pfsense serial number
Support & licensing (Netgate Plus) – Required for support tickets, TAC access, and Auto‑Config Backup (ACB). Device identification – Distinguish multiple firewalls in monitoring tools or logs. Configuration management – Match backups to specific instances. Auto‑Config Backup – The serial number is the key used to sync configs to Netgate’s cloud.
4. Changing or Regenerating the Serial Number
⚠️ Warning : Do not change the serial number on Netgate hardware. It voids support and ACB functionality. In pfSense software, a serial number is a
For pfSense CE (software only):
The serial number is generated on first boot and stored in /conf/config.xml . To regenerate (not recommended without need): pfSsh.php $config['system']['serial'] = strtoupper(bin2hex(openssl_random_pseudo_bytes(8))); write_config("Regenerated serial number"); exit
Then reboot.
5. Troubleshooting Serial Number Issues | Issue | Likely Cause | Solution | |-------|--------------|----------| | Serial number missing in WebGUI | Old config from pre‑2.3 version | Run config.xml upgrade via CLI | | Duplicate serial numbers | Cloned VM or disk image | Regenerate on each instance (CE only) | | ACB fails with “invalid serial” | Netgate Plus on non‑Netgate HW | This is unsupported; use CE instead | | Serial changes after reboot | Corrupt /conf/config.xml or R/W failure | Restore from backup, check filesystem | 6. Best Practices
Backup your config.xml – Contains the serial number; losing it may break cloud sync. Do not clone pfSense Plus VMs – Each must have unique hardware serial (set in hypervisor). For CE in HA (CARP) clusters – Keep serial numbers unique to avoid confusion in logs. Automate retrieval – Use: php -r "require('/etc/inc/config.lib.inc'); echo get_system_serial();"