Syslog

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.

Logging

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 UDP/TCP.

Console

set system syslog console facility <keyword> level <keyword>

Log syslog messages to /dev/console, for an explanation on Facilities keywords and Severity Level keywords see tables below.

Custom File

set system syslog file <filename> facility <keyword> level <keyword>

Log syslog messages to file specified via <filename>, for en explanation on Facilities keywords and 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 logiles after a number of gives bytes. We keep as many as <number> rotated file before they are deleted on the system.

Remote Host

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 en explanation on Facilities keywords and 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.

Local User Account

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 en explanation on Facilities keywords and Severity Level keywords see tables below.

Facilities

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	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	use 6 (local6)
23	local7	local use 7 (local7)

Severity Level

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.

Display Logs

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. Thos 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 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.