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syslog-ng Open Source Edition 3.38 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng The syslog-ng OSE quick-start guide The syslog-ng OSE configuration file source: Read, receive, and collect log messages
How sources work default-network-drivers: Receive and parse common syslog messages internal: Collecting internal messages file: Collecting messages from text files wildcard-file: Collecting messages from multiple text files kubernetes: Collecting and parsing the Kubernetes CRI (Container Runtime Interface) format linux-audit: Collecting messages from Linux audit logs mqtt: receiving messages from an MQTT broker network: Collecting messages using the RFC3164 protocol (network() driver) nodejs: Receiving JSON messages from nodejs applications mbox: Converting local email messages to log messages osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes pacct: Collecting process accounting logs on Linux program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources snmptrap: Read Net-SNMP traps sun-streams: Collecting messages on Sun Solaris syslog: Collecting messages using the IETF syslog protocol (syslog() driver) system: Collecting the system-specific log messages of a platform systemd-journal: Collecting messages from the systemd-journal system log storage systemd-syslog: Collecting systemd messages using a socket tcp, tcp6, udp, udp6: Collecting messages from remote hosts using the BSD syslog protocol— OBSOLETE unix-stream, unix-dgram: Collecting messages from UNIX domain sockets stdin: Collecting messages from the standard input stream
destination: Forward, send, and store log messages
amqp: Publishing messages using AMQP collectd: sending metrics to collectd discord: Sending alerts and notifications to Discord elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API file: Storing messages in plain-text files graphite: Sending metrics to Graphite Sending logs to Graylog hdfs: Storing messages on the Hadoop Distributed File System (HDFS) Posting messages over HTTP http: Posting messages over HTTP without Java kafka: Publishing messages to Apache Kafka (Java implementation) kafka-c(): Publishing messages to Apache Kafka using the librdkafka client (C implementation) loggly: Using Loggly logmatic: Using Logmatic.io mongodb(): Storing messages in a MongoDB database mqtt() destination: sending messages from a local network to an MQTT broker network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) osquery: Sending log messages to osquery's syslog table pipe: Sending messages to named pipes program: Sending messages to external applications pseudofile() python: writing custom Python destinations redis: Storing name-value pairs in Redis riemann: Monitoring your data with Riemann slack: Sending alerts and notifications to a Slack channel smtp: Generating SMTP messages (email) from logs snmp: Sending SNMP traps Splunk: Sending log messages to Splunk sql: Storing messages in an SQL database stomp: Publishing messages using STOMP Sumo Logic destinations: sumologic-http() and sumologic-syslog() syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng(): Forward logs to another syslog-ng node tcp, tcp6, udp, udp6: Sending messages to a remote log server using the legacy BSD-syslog protocol (tcp(), udp() drivers) Telegram: Sending messages to Telegram unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal: usertty() destination Write your own custom destination in Java or Python Client-side failover
log: Filter and route log messages using log paths, flags, and filters Global options of syslog-ng OSE TLS-encrypted message transfer template and rewrite: Format, modify, and manipulate log messages parser: Parse and segment structured messages
Parsing syslog messages Parsing messages with comma-separated and similar values Parsing key=value pairs JSON parser XML parser Parsing dates and timestamps Python parser Parsing tags Apache access log parser Linux audit parser Cisco parser Parsing enterprise-wide message model (EWMM) messages iptables parser Netskope parser panos-parser(): parsing PAN-OS log messages Sudo parser MariaDB parser Websense parser Fortigate parser Check Point Log Exporter parser Regular expression (regexp) parser db-parser: Process message content with a pattern database (patterndb)
Correlating log messages Enriching log messages with external data Statistics of syslog-ng Multithreading and scaling in syslog-ng OSE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd) License The syslog-ng Open Source Edition Documentation License Glossary

koCreating syslog-ng core files

Purpose:

When syslog-ng crashes for some reason, it can create a core file that contains important troubleshooting information. To enable core files, complete the following procedure:

Steps:

  1. Core files are produced only if the maximum core file size ulimit is set to a high value in the init script of syslog-ng.Add the following line to the init script of syslog-ng:

    ulimit -c unlimited

  2. Verify that syslog-ng has permissions to write the directory it is started from, for example, /opt/syslog-ng/sbin/.

  3. If syslog-ng crashes, it will create a core file in the directory syslog-ng was started from.

  4. To test that syslog-ng can create a core file, you can create a crash manually. For this, determine the PID of syslog-ng (for example, using the ps -All|grep syslog-ng command), then issue the following command: kill -ABRT <syslog-ng pid>

    This should create a core file in the current working directory.

Collecting debugging information with strace, truss, or tusc

To properly troubleshoot certain situations, it can be useful to trace which system calls syslog-ng OSE performs. How this is performed depends on the platform running syslog-ng OSE. In general, note the following points:

  • When syslog-ng OSE is started, a supervisor process might stay in the foreground, while the actual syslog-ng daemon goes to the background. Always trace the background process.

  • Apart from the system calls, the time between two system calls can be important as well. Make sure that your tracing tool records the time information as well. For details on how to do that, refer to the manual page of your specific tool (for example, strace on Linux, or truss on Solaris and BSD).

  • Run your tracing tool in verbose mode, and if possible, set it to print long output strings, so the messages are not truncated.

  • When using strace, also record the output of lsof to see which files are accessed.

The following are examples for tracing system calls of syslog-ng on some platforms. The output is saved into the /tmp/syslog-ng-trace.txt file, sufficed with the PID of the related syslog-ng process.The path of the syslog-ng binary may be different for your installation, as distribution-specific packages may use different paths.

  • Linux: strace -o /tmp/trace.txt -s256 -ff -ttT /opt/syslog-ng/sbin/syslog-ng -f /opt/syslog-ng/etc/syslog-ng.conf -Fdv

  • HP-UX: tusc -f -o /tmp/syslog-ng-trace.txt -T /opt/syslog-ng/sbin/syslog-ng

  • IBM AIX and Solaris: truss -f -o /tmp/syslog-ng-trace.txt -r all -w all -u libc:: /opt/syslog-ng/sbin/syslog-ng -d -d -d

TIP: To execute these commands on an already running syslog-ng OSE process, use the -p <pid_of_syslog-ng> parameter.

Running a failure script

Purpose:

You can create a failure script that is executed when syslog-ng OSE terminates abnormally, that is, when it exits with a non-zero exit code. For example, you can use this script to send an automatic email notification.

Prerequisites:

The failure script must be the following file: /opt/syslog-ng/sbin/syslog-ng-failure, and must be executable.

To create a sample failure script, complete the following steps.

Steps:

  1. Create a file named /opt/syslog-ng/sbin/syslog-ng-failure with the following content:

    #!/usr/bin/env bash
cat >>/tmp/test.txt <<EOF
$(date)
Name............$1
Chroot dir......$2
Pid file dir....$3
Pid file........$4
Cwd.............$5
Caps............$6
Reason..........$7
Argbuf..........$8
Restarting......$9

EOF

  2. Make the file executable: chmod +x /opt/syslog-ng/sbin/syslog-ng-failure

  3. Run the following command in the /opt/syslog-ng/sbin directory: ./syslog-ng --process-mode=safe-background; sleep 0.5; ps aux | grep './syslog-ng' | grep -v grep | awk '{print $2}' | xargs kill -KILL; sleep 0.5; cat /tmp/test.txt

    The command starts syslog-ng OSE in safe-background mode (which is needed to use the failure script) and then kills it. You should see that the relevant information is written into the /tmp/test.txt file, for example:

    Thu May 18 12:08:58 UTC 2017
Name............syslog-ng
Chroot dir......NULL
Pid file dir....NULL
Pid file........NULL
Cwd.............NULL
Caps............NULL
Reason..........signalled
Argbuf..........9
Restarting......not-restarting

  4. You should also see messages similar to the following in system syslog. The exact message depends on the signal (or the reason why syslog-ng OSE stopped):

    May 18 13:56:09 myhost supervise/syslog-ng[10820]: Daemon exited gracefully, not restarting; exitcode='0'
May 18 13:57:01 myhost supervise/syslog-ng[10996]: Daemon exited due to a deadlock/signal/failure, restarting; exitcode='131'
May 18 13:57:37 myhost supervise/syslog-ng[11480]: Daemon was killed, not restarting; exitcode='9'

    The failure script should run on every non-zero exit event.

Stopping syslog-ng

To avoid problems, always use the init scripts to stop syslog-ng (/etc/init.d/syslog-ng stop), instead of using the kill command. This is especially true on Solaris and HP-UX systems, here use /etc/init.d/syslog stop.

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