Every time syslog-ng is started, or its configuration is reloaded, it automatically logs the SHA-1 fingerprint of its configuration file using the internal() message source. That way any modification of the configuration of your syslog-ng clients is visible in the central logs. Note that the log message does not contain the exact change, nor can the configuration file be retrieved from the fingerprint. Only the fact of the configuration change can be detected.
Modular configuration files that are included in the main configuration file of syslog-ng PE are included when the fingerprint is calculated. However, other external files (for example, scripts used in program sources or destinations) are excluded, therefore their modifications do not change the fingerprint.
The fingerprint can be examined with the logchksign command-line application, which detects that the fingerprint was indeed generated by a syslog-ng application. Just paste the hashes from the log message after the logchksign command like in the following example:
bin/logchksign "cfg-fingerprint='832ef664ff79df8afc66cd955c0c8aaa3c343f31', cfg-nonce-ndx='0', cfg-signature='785223cfa19ad52b855550be141b00306347b0a9'"
The syslog-ng PE application is modular, to increase its flexibility and also to simplify the development of additional modules. Most of the functionality of syslog-ng PE is in separate modules. That way it becomes also possible to finetune the resource requirements of syslog-ng PE, for example, by loading only the modules that are actually used in the configuration, or simply omitting modules that are not used but require large amount of memory.
Each module contains one or more plugins, which add some functionality to syslog-ng PE, for example, a destination or a source driver.
To display the list of available modules, execute the syslog-ng --version command.
To the description of the available modules, execute the syslog-ng --module-registry command.
To customize which modules are loaded automatically when syslog-ng PE is started, use the --default-modules command-line option of syslog-ng PE.
To request loading a module from the syslog-ng PE configuration file, see Loading modules.
For details on the command-line parameters of syslog-ng PE mentioned in the previous list, see the syslog-ng PE man page at The syslog-ng manual page.
The syslog-ng Premium Edition application loads every available module during startup.
To load a module that is not loaded automatically, include the following statement in the syslog-ng PE configuration file:
Note the following points about the @module statement:
The @module statement is a top-level statement, that is, it cannot be nested into any other statement. Usually it is used immediately after the @version statement.
Every @module statement loads a single module: loading multiple modules requires a separate @module statement for every module.
In the configuration file, the @module statement of a module must be earlier than the module is used.
To disable loading every module automatically, set the autoload-compiled-modules global variable to 0 in your configuration file:
@define autoload-compiled-modules 0
Note that in this case, you have to explicitly load the modules you want to use.
The following sections describe some methods that can be useful to simplify the management of large-scale syslog-ng installations.