syslog-ng Open Source Edition 3.38 - Administration Guide

1. Install the syslog-ng application on the host. For details on installing syslog-ng on specific operating systems, see Installing syslog-ng.

2. Configure the network sources that collect the log messages sent by the clients.

3. Create a network destination that points to the syslog-ng server.

4. Create a log statement connecting the network sources to the syslog-ng server.

5. Configure the local sources that collect the log messages of the relay host.

6. Create a log statement connecting the local sources to the syslog-ng server.

7. Enable the keep-hostname() and disable the chain-hostnames() options. (For details on how these options work, see chain-hostnames().)

   NOTE: It is recommended to use these options on your syslog-ng OSE server as well.

8. Set filters and options (for example, TLS encryption) as necessary.

   NOTE: By default, the syslog-ng server will treat the relayed messages as if they were created by the relay host, not the host that originally sent them to the relay. In order to use the original hostname on the syslog-ng server, use the keep-hostname(yes) option both on the syslog-ng relay and the syslog-ng server. This option can be set individually for every source if needed.

   If you are relaying log messages and want to resolve IP addresses to hostnames, configure the first relay to do the name resolution.

   Example: A simple configuration for relays

   The following is a simple configuration file that collects local and incoming log messages and forwards them to a logserver using the IETF-syslog protocol.

   @version: 3.38
   @include "scl.conf"
   options {
       time-reap(30);
       mark-freq(10);
       keep-hostname(yes);
       chain-hostnames(no);
   };
   source s_local {
       system(); internal();
   };
   source s_network {
       syslog(transport(tcp));
   };
   destination d_syslog_tcp {
       syslog("192.168.1.5" transport("tcp") port(2010));
   };
   log {
       source(s_local); source(s_network);
       destination(d_syslog_tcp);
   };

Starting syslog-ng OSE

To start syslog-ng OSE, execute the following command as root.

If the service starts successfully, no output will be displayed.

The following message indicates that syslog-ng OSE can not start (see Checking syslog-ng OSE status):

Job for syslog-ng.service failed because the control process exited with error code. See systemctl status syslog-ng.service and journalctl -xe for details.

Stopping syslog-ng OSE

To stop syslog-ng OSE

1. Execute the following command as root.

   Example: command for stopping syslog-ng OSE

   systemctl stop syslog-ng

2. Check the status of syslog-ng OSE service (see Checking syslog-ng OSE status).

Restarting syslog-ng OSE

To restart syslog-ng OSE, execute the following command as root.

Reloading configuration file without restarting syslog-ng OSE

To reload the configuration file without restarting syslog-ng OSE, execute the following command as root.

Checking syslog-ng OSE status

To check the following status-related components, observe the suggestions below.

• Checking the status of syslog-ng OSE service

  To check the status of syslog-ng OSE service

  1. Execute the following command as root.

     Example: command for checking the status of syslog-ng OSE service

     systemctl --no-pager status syslog-ng

  2. Check the Active: field, which shows the status of syslog-ng OSE service. The following statuses are possible:

     • active (running) - syslog-ng OSE service is up and running

       Example: syslog-ng OSE service active

       syslog-ng.service - System Logger Daemon
       Loaded: loaded (/lib/systemd/system/syslog-ng.service; enabled; vendor preset: enabled)
       Active: active (running) since Tue 2019-06-25 08:58:09 CEST; 5s ago
       Main PID: 6575 (syslog-ng)
       Tasks: 3
       Memory: 13.3M
       CPU: 268ms
       CGroup: /system.slice/syslog-ng.service
       6575 /opt/syslog-ng/libexec/syslog-ng -F --no-caps --enable-core

     • inactive (dead) - syslog-ng service is stopped

       Example: syslog-ng OSE status inactive

       syslog-ng.service - System Logger Daemon
       Loaded: loaded (/lib/systemd/system/syslog-ng.service; enabled; vendor preset: enabled)
       Active: inactive (dead) since Tue 2019-06-25 09:14:16 CEST; 2min 18s ago
       Process: 6575 ExecStart=/opt/syslog-ng/sbin/syslog-ng -F --no-caps --enable-core $SYSLOGNG_OPTIONS (code=exited, status=0/SUCCESS)
       Main PID: 6575 (code=exited, status=0/SUCCESS)
       Status: "Shutting down... Tue Jun 25 09:14:16 2019"
       Jun 25 09:14:31 as-syslog-srv systemd: Stopped System Logger Daemon.

• Checking the process of syslog-ng OSE

  To check the process of syslog-ng OSE, execute one of the following commands.

  • Example: command ps u `pidof syslog-ng`

    ps u `pidof syslog-ng`

    Expected output example:

    USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

    syslogng 6709 0.0 0.6 308680 13432 ? Ss 09:17 0:00 /opt/syslog-ng/libexec/syslog-ng -F --no-caps --enable-core

  • Example: command ps axu | grep syslog-ng | grep -v grep

    ps axu | grep syslog-ng | grep -v grep

    Expected output example:

    syslogng 6709 0.0 0.6 308680 13432 ? Ss 09:17 0:00 /opt/syslog-ng/libexec/syslog-ng -F --no-caps --enable-core

• Checking the internal logs of syslog-ng OSE

  The internal logs of syslog-ng OSE contains informal, warning and error messages.

  By default, syslog-ng OSE log messages (generated on the internal() source) are written to /var/log/messages.

  Check the internal logs of syslog-ng OSE for any issue.

• Message processing

  The syslog-ng OSE application collects statistics about the number of processed messages on the different sources and destinations.

  NOTE: When using syslog-ng-ctl stats, consider that while the output is generally consistent, there is no explicit ordering behind the command. Consequently, One Identity does not recommend creating parsers that depend on a fix output order.

  If needed, you can sort the output with an external application, for example, | sort.

  • Central statistics

    To check the central statistics, execute the following command to see the number of received and queued (sent) messages by syslog-ng OSE.

    Example: command for checking central statistics

    watch "/opt/syslog-ng/sbin/syslog-ng-ctl stats | grep ^center"

    The output will be updated in every 2 seconds.

    If the numbers are changing, syslog-ng OSE is processing the messages.

    Example: output example

    Every 2.0s: /opt/syslog-ng/sbin/syslog-ng-ctl stats | grep ^center       Tue Jun 25 10:33:25 2019
    center;;queued;a;processed;112
    center;;received;a;processed;28

  • Source statistics

    To check the source statistics, execute the following command to see the number of received messages on the configured sources.

    Example: command for checking central statistics

    watch "/opt/syslog-ng/sbin/syslog-ng-ctl stats | grep ^source"

    The output will be updated in every 2 seconds.

    If the numbers are changing, syslog-ng OSE is receiving messages on the sources.

    Example: output example

    Every 2.0s: /opt/syslog-ng/sbin/syslog-ng-ctl stats | grep ^source      Tue Jun 25 10:40:50 2019
    source;s_null;;a;processed;0
    source;s_net;;a;processed;0
    source;s_local;;a;processed;90

  • Destination statistics

    To check the source statistics, execute the following command to see the number of received messages on the configured sources.

    Example: command for checking destination statistics

    watch "/opt/syslog-ng/sbin/syslog-ng-ctl stats | grep ^source"

    The output will be updated in every 2 seconds.

    If the numbers are changing, syslog-ng OSE is receiving messages on the sources.

    Example: output example

    Every 2.0s: /opt/syslog-ng/sbin/syslog-ng-ctl stats | grep ^destination      Tue Jun 25 10:41:02 2019
    destination;d_logserver2;;a;processed;90
    destination;d_messages;;a;processed;180
    destination;d_logserver;;a;processed;90
    destination;d_null;;a;processed;0