Per default VyOSs has minimal syslog logging enabled which is stored and rotated locally. Errors will be always logged to a local file, which includes local7 error messages, emergency messages will be sent to the console, too.
To configure syslog, you need to switch into configuration mode.
Syslog supports logging to multiple targets, those targets could be a plain file on your VyOS installation itself, a serial console or a remote syslog server which is reached via IP (Internet Protocol) UDP/TCP.
set system syslog console facility <keyword> level <keyword>
Log syslog messages to /dev/console, for an explanation on syslog_facilities keywords and syslog_severity_level keywords see tables below.
set system syslog file <filename> facility <keyword> level <keyword>
Log syslog messages to file specified via <filename>, for an explanation on syslog_facilities keywords and syslog_severity_level keywords see tables below.
set system syslog file <filename> archive size <size>
Syslog will write <size> kilobytes into the file specified by <filename>. After this limit has been reached, the custom file is "rotated" by logrotate and a new custom file is created.
set system syslog file <filename> archive file <number>
Syslog uses logrotate to rotate logfiles after a number of gives bytes. We keep as many as <number> rotated file before they are deleted on the system.
Logging to a remote host leaves the local logging configuration intact, it can be configured in parallel to a custom file or console logging. You can log to multiple hosts at the same time, using either TCP or UDP. The default is sending the messages via port 514/UDP.
set system syslog host <address> facility <keyword> level <keyword>
Log syslog messages to remote host specified by <address>. The address can be specified by either FQDN or IP address. For an explanation on syslog_facilities keywords and syslog_severity_level keywords see tables below.
set system syslog host <address> facility <keyword> protocol <udp|tcp>
Configure protocol used for communication to remote syslog host. This can be either UDP or TCP.
set system syslog vrf <name>
Specify name of the VRF (Virtual Routing and Forwarding) instance.
set system syslog user <username> facility <keyword> level <keyword>
If logging to a local user account is configured, all defined log messages are display on the console if the local user is logged in, if the user is not logged in, no messages are being displayed. For an explanation on syslog_facilities keywords and syslog_severity_level keywords see tables below.
List of facilities used by syslog. Most facilities names are self explanatory. Facilities local0 - local7 common usage is f.e. as network logs facilities for nodes and network equipment. Generally it depends on the situation how to classify logs and put them to facilities. See facilities more as a tool rather than a directive to follow.
Facilities can be adjusted to meet the needs of the user:
| Facility Code | Keyword | Description |
|---|---|---|
| all | All facilities | |
| 0 | kern | Kernel messages |
| 1 | user | User-level messages |
| 2 | Mail system | |
| 3 | daemon | System daemons |
| 4 | auth | Security/authentication messages |
| 5 | syslog | Messages generated internally by syslogd |
| 6 | lpr | Line printer subsystem |
| 7 | news | Network news subsystem |
| 8 | uucp | UUCP subsystem |
| 9 | cron | Clock daemon |
| 10 | security | Security/authentication messages |
| 11 | ftp | FTP daemon |
| 12 | ntp | NTP subsystem |
| 13 | logaudit | Log audit |
| 14 | logalert | Log alert |
| 15 | clock | clock daemon (note 2) |
| 16 | local0 | local use 0 (local0) |
| 17 | local1 | local use 1 (local1) |
| 18 | local2 | local use 2 (local2) |
| 19 | local3 | local use 3 (local3) |
| 20 | local4 | local use 4 (local4) |
| 21 | local5 | local use 5 (local5) |
| 22 | local6 |
|
| 23 | local7 | local use 7 (local7) |
| Value | Severity | Keyword | Description |
|---|---|---|---|
| all | Log everything | ||
| 0 | Emergency | emerg | System is unusable - a panic condition |
| 1 | Alert | alert | Action must be taken immediately - A condition that should be corrected immediately, such as a corrupted system database. |
| 2 | Critical | crit | Critical conditions - e.g. hard drive errors. |
| 3 | Error | err | Error conditions |
| 4 | Warning | warning | Warning conditions |
| 5 | Notice | notice | Normal but significant conditions -conditions that are not error conditions, but that may require special handling. |
| 6 | Informational | info | Informational messages |
| 7 | Debug | debug | Debug-level messages - Messages that contain information normally of use only when debugging a program. |
show log [all | authorization | cluster | conntrack-sync | ...]
Display log files of given category on the console. Use tab completion to get a list of available categories. Those categories could be: all, authorization, cluster, conntrack-sync, dhcp, directory, dns, file, firewall, https, image lldp, nat, openvpn, snmp, tail, vpn, vrrp
If no option is specified, this defaults to all.
show log image <name> [all | authorization | directory | file <file name> | tail <lines>]
Log messages from a specified image can be displayed on the console. Details of allowed parameters:
| all | Display contents of all master log files of the specified image |
| authorization | Display all authorization attempts of the specified image |
| directory | Display list of all user-defined log files of the specified image |
| file <file name> | Display contents of a specified user-defined log file of the specified image |
| tail | Display last lines of the system log of the specified image |
| <lines> | Number of lines to be displayed, default 10 |
When no options/parameters are used, the contents of the main syslog file are displayed.
Hint
Use show log | strip-private if you want to hide private data when sharing your logs.
delete log file <text>
Deletes the specified user-defined file <text> in the /var/log/user directory
Note that deleting the log file does not stop the system from logging events. If you use this command while the system is logging events, old log events will be deleted, but events after the delete operation will be recorded in the new file. To delete the file altogether, first delete logging to the file using system syslog custom-file command, and then delete the file.