syslog-ng Open Source Edition 3.22 - Administration Guide

system: Collecting the system-specific log messages of a platform

Starting with version 3.2, syslog-ng OSE can automatically collect the system-specific log messages of the host on a number of platforms using the system() driver. If the system() driver is included in the syslog-ng OSE configuration file, syslog-ng OSE automatically adds the following sources to the syslog-ng OSE configuration.

The system() driver is also used in the default configuration file of syslog-ng OSE. For details on the default configuration file, see Example: The default configuration file of syslog-ng OSE. Starting with syslog-ng OSE version 3.6, you can use the system-expand command-line utility (which is a shell script, located in the modules/system-source/ directory) to display the configuration that the system() source will use.

Starting with version 3.6, syslog-ng OSE parses messages complying with the Splunk Common Information Model (CIM) and marked with @cim as JSON messages (for example, the ulogd from the netfilter project can emit such messages). That way, you can forward such messages without losing any information to CIM-aware applications (for example, Splunk).

unix-dgram("/dev/log");

unix-dgram("/var/run/log");

unix-dgram("/var/run/logpriv" perm(0600));

file("/dev/klog" follow-freq(0) program-override("kernel") flags(no-parse));

unix-dgram("/var/run/log");

file("/dev/klog" follow-freq(0) program-override("kernel"));

pipe("/dev/log" pad-size(2048));

unix-dgram("/dev/log");

file("/proc/kmsg" program-override("kernel") flags(kernel));

sun-streams("/dev/log");

sun-streams("/dev/log" door("/etc/.syslog_door"));

sun-streams("/dev/log" door("/var/run/syslog_door"));

system() source options

The system() driver has the following options:

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

Using the hook-commands() when syslog-ng OSE starts or stops

To execute an external program when syslog-ng OSE starts or stops, use the following options:

Using the hook-commands() when syslog-ng OSE reloads

To execute an external program when the syslog-ng OSE configuration is initiated or torn down, for example, on startup/shutdown or during a syslog-ng OSE reload, use the following options:

source {
   network(transport(udp)
	hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};

systemd-journal: Collecting messages from the systemd-journal system log storage

The systemd-journal() source is used on various Linux distributions, such as RHEL (from RHEL7) and CentOS. The systemd-journal() source driver can read the structured name-value format of the journald system service, making it easier to reach the custom fields in the message. By default, syslog-ng OSE adds the .journald. prefix to the name of every parsed value. For a list and description of name-value pairs that journald provides, see the documentation of journald for your platform (for example, man systemd.journal-fields).

The systemd-journal() source driver is designed to read only local messages through the systemd-journal API. It is not possible to set the location of the journal files, or the directories.

systemd-journal(options);

@version: 3.22

source s_journald {
    systemd-journal(prefix(".SDATA.journald."));
};

destination d_network {
    syslog("server.host");
};

log {
    source(s_journald);
    destination(d_network);
};

@version: 3.22

source s_journald {
    systemd-journal(prefix(".SDATA.journald."));
};

filter f_uid {"${.SDATA.journald._UID}" eq "1000"};

destination d_network {
    syslog("server.host");
};

log {
    source(s_journald);
    filter(f_uid);
    destination(d_network);
};

@version: 3.22

source s_local {
    systemd-journal(prefix("journald."));
};

destination d_network {
    network("server.host" template("$(format_json --scope rfc5424 --key journald.*)\n"));
};

log {
    source(s_local);
    destination(d_network);
};

The journal contains credential information about the process that sent the log message. The syslog-ng OSE application makes this information available in the following macros:

systemd-journal() source options

The systemd-journal() driver has the following options:

default-facility()

Description: The default facility value if the SYSLOG_FACILITY entry does not exist.

default-level()

Description: The default level value if the PRIORITY entry does not exist.

default-level()

Description: The default level value if the PRIORITY entry does not exist.

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

Using the hook-commands() when syslog-ng OSE starts or stops

To execute an external program when syslog-ng OSE starts or stops, use the following options:

Using the hook-commands() when syslog-ng OSE reloads

To execute an external program when the syslog-ng OSE configuration is initiated or torn down, for example, on startup/shutdown or during a syslog-ng OSE reload, use the following options:

source {
   network(transport(udp)
	hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};

host-override()

Description: Replaces the ${HOST} part of the message with the parameter string.

keep-hostname()

Description: Enable or disable hostname rewriting.

• If enabled (keep-hostname(yes)), syslog-ng OSE will retain the hostname information read from the systemd journal messages.

• If disabled (keep-hostname(no)), syslog-ng OSE will use the hostname that has been set up for the operating system instance that syslog-ng is running on. To query or set this value, use the hostnamectl command.

This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

max-field-size()

Description: The maximum length of a field's value.

prefix()

Description: If this option is set, every non-built-in mapped names get a prefix (for example: ".SDATA.journald."). By default, syslog-ng OSE adds the .journald. prefix to every value.

read-old-records()

Description: If set to yes, syslog-ng OSE will start reading the records from the beginning of the journal, if the journal has not been read yet. If set to no, syslog-ng OSE will read only the new records. If the source has a state in the persist file, this option will have no effect.

time-zone()

Description: The default timezone for messages read from the source. Applies only if no timezone is specified within the message itself.

The timezone can be specified by using the name, for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format, for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.

use-fqdn()

Description: Add Fully Qualified Domain Name instead of short hostname. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.