Technical Documentation

Specifying the Facility and Severity of Messages to Include in the Log

Each system log message belongs to a facility, which groups together messages that either are generated by the same source (such as a software process) or concern a similar condition or activity (such as authentication attempts). Each message is also preassigned a severity level, which indicates how seriously the triggering event affects routing platform functions.

When you configure logging for a facility and destination, you specify a severity level for each facility. Messages from the facility that are rated at that level or higher are logged to the following destination:

[edit system syslog]
(console | file filename | host destination | user username) {
	facility severity ;

For more information about the destinations, see Directing Messages to a User Terminal,Directing Messages to a User Terminal, Directing Messages to the Console.

To log messages belonging to more than one facility to a particular destination, specify each facility and associated severity as a separate statement within the set of statements for the destination.

Table 1 lists the facilities that you can specify in configuration statements at the [edit system syslog] hierarchy level.

Table 1: JUNOS System Logging Facilities

FacilityType of Event or Error


All (messages from all facilities)


Authentication and authorization attempts


Changes to the JUNOS configuration


Specified configuration is invalid on the routing platform type


Actions performed or errors encountered by system processes


Events related to dynamic flow capture


Packet filtering actions performed by a firewall filter


Actions performed or errors encountered by the FTP process


Commands issued at the JUNOS command-line interface (CLI) prompt or invoked by a client application such as a JUNOScript or NETCONF client


Actions performed or errors encountered by the JUNOS kernel


Actions performed or errors encountered by the Packet Forwarding Engine


Actions performed or errors encountered by user-space processes

Table 2 lists the severity levels that you can specify in configuration statements at the [edit system syslog] hierarchy level. The levels from emergency through info are in order from highest severity (greatest effect on functioning) to lowest.

Unlike the other severity levels, the none level disables logging of a facility instead of indicating how seriously a triggering event affects routing functions. For more information, see Disabling Logging of a Facility.

Table 2: System Log Message Severity Levels

Severity LevelDescription


Includes all severity levels


Disables logging of the associated facility to a destination


System panic or other condition that causes the routing platform to stop functioning


Conditions that require immediate correction, such as a corrupted system database


Critical conditions, such as hard drive errors


Error conditions that generally have less serious consequences than errors in the emergency, alert, and critical levels


Conditions that warrant monitoring


Conditions that are not errors but might warrant special handling


Events or nonerror conditions of interest

Published: 2010-04-28