Setting up syslog support

This document will explain how to send syslog data to LibreNMS.

Syslog server installation

syslog-ng

For Debian / Ubuntu:

apt-get install syslog-ng

For CentOS / RedHat

yum install syslog-ng

Once syslog-ng is installed, edit the relevant config file (most likely /etc/syslog-ng/syslog-ng.conf) and paste the following:

@version: 3.5
@include "scl.conf"
@include "`scl-root`/system/tty10.conf"

# First, set some global options.
options {
        chain_hostnames(off);
        flush_lines(0);
        use_dns(no);
        use_fqdn(no);
        owner("root");
        group("adm");
        perm(0640);
        stats_freq(0);
        bad_hostname("^gconfd$");
};

########################
# Sources
########################
source s_sys {
       system();
       internal();
};

source s_net {
        tcp(port(514) flags(syslog-protocol));
        udp(port(514) flags(syslog-protocol));
};

########################
# Destinations
########################
destination d_librenms {
        program("/opt/librenms/syslog.php" template ("$HOST||$FACILITY||$PRIORITY||$LEVEL||$TAG||$YEAR-$MONTH-$DAY $HOUR:$MIN:$SEC||$MSG||$PROGRAM\n") template-escape(yes));
};

########################
# Log paths
########################
log {
        source(s_net);
        source(s_sys);
        destination(d_librenms);
};

###
# Include all config files in /etc/syslog-ng/conf.d/
###
@include "/etc/syslog-ng/conf.d/*.conf"

Next start syslog-ng:

service syslog-ng restart

Add the following to your LibreNMS config.php file to enable the Syslog extension:

$config['enable_syslog'] = 1;

rsyslog

If you prefer rsyslog, here are some hints on how to get it working.

Add the following to your rsyslog config somewhere (could be at the top of the file in the step below, could be in rsyslog.conf if you are using remote logs for something else on this host)

# Listen for syslog messages on UDP:514
$ModLoad imudp
$UDPServerRun 514

Create a file called something like /etc/rsyslog.d/30-librenms.conf containing:

# Feed syslog messages to librenms
$ModLoad omprog

$template librenms,"%fromhost%||%syslogfacility%||%syslogpriority%||%syslogseverity%||%syslogtag%||%$year%-%$month%-%$day% %timereported:8:25%||%msg%||%programname%\n"

*.* action(type="omprog" binary="/opt/librenms/syslog.php" template="librenms")

& stop

Ancient versions of rsyslog may require different syntax.

This is an example for rsyslog 5 (default on Debian 7):

# Feed syslog messages to librenms
$ModLoad omprog
$template librenms,"%FROMHOST%||%syslogfacility-text%||%syslogpriority-text%||%syslogseverity%||%syslogtag%||%$YEAR%-%$MONTH%-%$DAY% %timegenerated:8:25%||%msg%||%programname%\n"

$ActionOMProgBinary /opt/librenms/syslog.php
*.* :omprog:;librenms

If your rsyslog server is recieving messages relayed by another syslog server, you may try replacing %fromhost% with %hostname%, since fromhost is the host the message was received from, not the host that generated the message. The fromhost property is preferred as it avoids problems caused by devices sending incorrect hostnames in syslog messages.

Add the following to your LibreNMS config.php file to enable the Syslog extension:

$config['enable_syslog'] = 1;

Client configuration

Below are sample configurations for a variety of clients. You should understand the config before using it as you may want to make some slight changes.

Replace librenms.ip with IP or hostname of your LibreNMS install.

Replace any variables in with the relevant information.

syslog

*.*     @librenms.ip

rsyslog

*.* @librenms.ip:514

Cisco ASA

logging enable
logging timestamp
logging buffer-size 200000
logging buffered debugging
logging trap notifications
logging host <outside interface name> librenms.ip

Cisco IOS

logging trap debugging
logging facility local6
logging librenms.ip

Cisco NXOS

logging server librenms.ip 5 use-vrf default facility local6

If you have permitted udp and tcp 514 through any firewall then that should be all you need. Logs should start appearing and displayed within the LibreNMS web UI.