Chat now with support
Chat with Support

syslog-ng Premium Edition 7.0.24 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng PE The syslog-ng PE quick-start guide The syslog-ng PE configuration file Collecting log messages — sources and source drivers
How sources work default-network-drivers: Receive and parse common syslog messages internal: Collecting internal messages file: Collecting messages from text files google-pubsub: collecting messages from the Google Pub/Sub messaging service wildcard-file: Collecting messages from multiple text files linux-audit: Collecting messages from Linux audit logs mssql, oracle, sql: collecting messages from an SQL database network: Collecting messages using the RFC3164 protocol (network() driver) office365: Fetching logs from Office 365 osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources snmptrap: Read Net-SNMP traps 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 udp-balancer: Receiving UDP messages at very high rate unix-stream, unix-dgram: Collecting messages from UNIX domain sockets windowsevent: Collecting Windows event logs
Sending and storing log messages — destinations and destination drivers
elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Event Collector file: Storing messages in plain-text files google_pubsub: Sending logs to the Google Cloud Pub/Sub messaging service hdfs: Storing messages on the Hadoop Distributed File System (HDFS) http: Posting messages over HTTP kafka: Publishing messages to Apache Kafka logstore: Storing messages in encrypted files mongodb: Storing messages in a MongoDB database network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) pipe: Sending messages to named pipes program: Sending messages to external applications python: writing custom Python destinations sentinel: Sending logs to the Microsoft Azure Sentinel cloud snmp: Sending SNMP traps smtp: Generating SMTP messages (email) from logs splunk-hec: Sending messages to Splunk HTTP Event Collector sql: Storing messages in an SQL database stackdriver: Sending logs to the Google Stackdriver cloud 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) unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal — usertty() destination Client-side failover
Routing messages: log paths, flags, and filters Global options of syslog-ng PE TLS-encrypted message transfer Advanced Log Transfer Protocol Reliability and minimizing the loss of log messages Manipulating messages parser: Parse and segment structured messages Processing message content with a pattern database Correlating log messages Enriching log messages with external data Monitoring statistics and metrics of syslog-ng Multithreading and scaling in syslog-ng PE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Glossary

file() source options

The file() driver has the following options:

default-facility()
Type: facility string
Default: kern
default-priority()
Type: priority string
Default:

Description: This parameter assigns an emergency level to the messages received from the file source, if the message does not specify one. For example, default-priority(warning)

encoding()
Type: string
Default:

Description: Specifies the characterset (encoding, for example, UTF-8) of messages using the legacy BSD-syslog protocol. To list the available character sets on a host, execute the iconv -l command. For details on how encoding affects the size of the message, see Message size and encoding.

flags()
Type: assume-utf8, empty-lines, expect-hostname, guess-timezone, kernel, no-hostname, no-multi-line, no-parse, sanitize-utf8, store-legacy-msghdr, store-raw-message, syslog-protocol, validate-utf8
Default: empty set

Description: Specifies the log parsing options of the source.

  • assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.

  • empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, syslog-ng PE removes empty lines automatically.

  • expect-hostname: If the expect-hostname flag is enabled, syslog-ng PE will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.

  • kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.

  • no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way syslog-ng PE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:

    source s_dell {
        network(
            port(2000)
            flags(no-hostname)
        );
    };
  • no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.

  • no-parse: By default, syslog-ng PE parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The syslog-ng PE application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.

    If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, syslog-ng PE generates a new syslog header (timestamp, host, and so on) automatically. Note that since flags(no-parse) disables message parsing, it interferes with other flags, for example, disables flags(no-multi-line).

  • dont-store-legacy-msghdr: By default, syslog-ng stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (syslog-ng automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.

  • sanitize-utf8: When using the sanitize-utf8 flag, syslog-ng PE converts non-UTF-8 input to an escaped form, which is valid UTF-8.

  • store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another syslog-ng node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 7.0.9 and later.

  • syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.

  • validate-utf8: The validate-utf8 flag enables encoding-verification for messages formatted according to the new IETF syslog standard (for details, see IETF-syslog messages). If theBOM1character is missing, but the message is otherwise UTF-8 compliant, syslog-ng automatically adds the BOM character to the message.

follow-freq()
Type: number
Default: 1

Description: Indicates that the source should be checked periodically. This is useful for files which always indicate readability, even though no new lines were appended. If this value is higher than zero, syslog-ng will not attempt to use poll() on the file, but checks whether the file changed every time the follow-freq() interval (in seconds) has elapsed. Floating-point numbers (for example, 1.5) can be used as well.

keep-timestamp()
Type: yes or no
Default: yes

Description: Specifies whether syslog-ng should accept the timestamp received from the sending application or client. If disabled, the time of reception will be used instead. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

Caution:

To use the S_ macros, the keep-timestamp() option must be enabled (this is the default behavior of syslog-ng PE).

log-fetch-limit()
Type: number
Default: 10

Description: The maximum number of messages fetched from a source during a single poll loop. The destination queues might fill up before flow-control could stop reading if log-fetch-limit() is too high.

log-iw-size()
Type: number
Default: 10000

Description: The size of the initial window, this value is used during flow control. Make sure that log-iw-size() is larger than the value of log-fetch-limit().

log-msg-size()
Type: number (bytes)
Default: Use the global log-msg-size() option, which defaults to 65536 (64 KiB).

Description: Maximum length of a message in bytes. This length includes the entire message (the data structure and individual fields). The maximal value that can be set is 268435456 bytes (256 MiB).

For messages using the IETF-syslog message format (RFC5424), the maximal size of the value of an SDATA field is 64 KiB.

NOTE: In most cases, log-msg-size() does not need to be set higher than 10 MiB.

For details on how encoding affects the size of the message, see Message size and encoding.

Uses the value of the global option if not specified.

log-prefix() (DEPRECATED)
Type: string
Default:

Description: A string added to the beginning of every log message. It can be used to add an arbitrary string to any log source, though it is most commonly used for adding kernel: to the kernel messages on Linux. NOTE: This option is deprecated. Use program-override() instead.

multi-line-garbage()
Type: regular expression
Default: empty string

Description: Use the multi-line-garbage() option when processing multi-line messages that contain unneeded parts between the messages. Specify a string or regular expression that matches the beginning of the unneeded message parts. If the multi-line-garbage() option is set, syslog-ng PE ignores the lines between the line matching the multi-line-garbage() and the next line matching multi-line-prefix(). See also the multi-line-prefix() option.

When receiving multi-line messages from a source when the multi-line-garbage() option is set, but no matching line is received between two lines that match multi-line-prefix(), syslog-ng PE will continue to process the incoming lines as a single message until a line matching multi-line-garbage() is received.

To use the multi-line-garbage() option, set the multi-line-mode() option to prefix-garbage.

Caution:

If the multi-line-garbage() option is set, syslog-ng PE discards lines between the line matching the multi-line-garbage() and the next line matching multi-line-prefix().

multi-line-mode()
Type: indented|regexp
Default: empty string

Description: Use the multi-line-mode() option when processing multi-line messages. The syslog-ng PE application provides the following methods to process multi-line messages: multi-line-mode(indented), and multi-line-mode(prefix-garbage).

  • The indented mode can process messages where each line that belongs to the previous line is indented by whitespace, and the message continues until the first non-indented line. For example, the Linux kernel (starting with version 3.5) uses this format for /dev/log, as well as several applications, like Apache Tomcat.

    Example: Processing indented multi-line messages
    source s_tomcat {
        file("/var/log/tomcat/xxx.log"
            multi-line-mode(indented)
        );
    };
  • The prefix-garbage mode uses a string or regular expression (set in multi-line-prefix()) that matches the beginning of the log messages, ignores newline characters from the source until a line matches the regular expression again, and treats the lines between the matching lines as a single message. For details on using multi-line-mode(prefix-garbage), see the multi-line-prefix() and multi-line-garbage() options.

  • The prefix-suffix mode uses a string or regular expression (set in multi-line-prefix()) that matches the beginning of the log messages, ignores newline characters from the source until a line matches the regular expression set in multi-line-suffix(), and treats the lines between multi-line-prefix() and multi-line-suffix() as a single message. Any other lines between the end of the message and the beginning of a new message (that is, a line that matches the multi-line-prefix() expression) are discarded. For details on using multi-line-mode(prefix-suffix), see the multi-line-prefix() and multi-line-suffix() options.

    The prefix-suffix mode is similar to the prefix-garbage mode, but it appends the garbage part to the message instead of discarding it.

TIP:
  • To make multi-line messages more readable when written to a file, use a template in the destination and instead of the ${MESSAGE} macro, use the following: $(indent-multi-line ${MESSAGE}). This expression inserts a tab after every newline character (except when a tab is already present), indenting every line of the message after the first. For example:

    destination d_file {
        file ("/var/log/messages"
            template("${ISODATE} ${HOST} $(indent-multi-line ${MESSAGE})\n")
        );
    };

    For details on using templates, see Templates and macros.

  • To actually convert the lines of multi-line messages to single line (by replacing the newline characters with whitespaces), use the flags(no-multi-line) option in the source.

multi-line-prefix()
Type: regular expression starting with the ^ character
Default: empty string

Description: Use the multi-line-prefix() option to process multi-line messages, that is, log messages that contain newline characters (for example, Tomcat logs). Specify a string or regular expression that matches the beginning of the log messages (always start with the ^ character). Use as simple regular expressions as possible, because complex regular expressions can severely reduce the rate of processing multi-line messages. If the multi-line-prefix() option is set, syslog-ng PE ignores newline characters from the source until a line matches the regular expression again, and treats the lines between the matching lines as a single message. See also the multi-line-garbage() option.

TIP:
  • To make multi-line messages more readable when written to a file, use a template in the destination and instead of the ${MESSAGE} macro, use the following: $(indent-multi-line ${MESSAGE}). This expression inserts a tab after every newline character (except when a tab is already present), indenting every line of the message after the first. For example:

    destination d_file {
        file ("/var/log/messages"
            template("${ISODATE} ${HOST} $(indent-multi-line ${MESSAGE})\n")
        );
    };

    For details on using templates, see Templates and macros.

  • To actually convert the lines of multi-line messages to single line (by replacing the newline characters with whitespaces), use the flags(no-multi-line) option in the source.

Example: Processing Tomcat logs

The log messages of the Apache Tomcat server are a typical example for multi-line log messages. The messages start with the date and time of the query in the YYYY.MM.DD HH:MM:SS format, as you can see in the following example.

2010.06.09. 12:07:39 org.apache.catalina.startup.Catalina start
SEVERE: Catalina.start:
LifecycleException:  service.getName(): "Catalina";  Protocol handler start failed: java.net.BindException: Address already in use null:8080
       at org.apache.catalina.connector.Connector.start(Connector.java:1138)
       at org.apache.catalina.core.StandardService.start(StandardService.java:531)
       at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
       at org.apache.catalina.startup.Catalina.start(Catalina.java:583)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
       at java.lang.reflect.Method.invoke(Method.java:597)
       at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
       at java.lang.reflect.Method.invoke(Method.java:597)
       at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:177)
2010.06.09. 12:07:39 org.apache.catalina.startup.Catalina start
INFO: Server startup in 1206 ms
2010.06.09. 12:45:08 org.apache.coyote.http11.Http11Protocol pause
INFO: Pausing Coyote HTTP/1.1 on http-8080
2010.06.09. 12:45:09 org.apache.catalina.core.StandardService stop
INFO: Stopping service Catalina

To process these messages, specify a regular expression matching the timestamp of the messages in the multi-line-prefix() option. Such an expression is the following:

source s_file{file("/var/log/tomcat6/catalina.2010-06-09.log" follow-freq(0) multi-line-prefix("[0-9]{4}\.[0-9]{2}\.[0-9]{2}\.") flags(no-parse));};
};

Note that flags(no-parse) is needed to prevent syslog-ng PE trying to interpret the date in the message.

multi-line-suffix()
Type: regular expression
Default: empty string

Description: Use the multi-line-suffix() option when processing multi-line messages. Specify a string or regular expression that matches the end of the multi-line message.

To use the multi-line-suffix() option, set the multi-line-mode() option to prefix-suffix. See also the multi-line-prefix() option.

multi-line-timeout()
Type: number [seconds]
Default:

[0 == disable]

Description: If any multi-line option is enabled, there are two possible scenarios:

  • the requirement specified in any multi-line option is met, which results in syslog-ng PE sending the full message (even multi-line messages)
  • the number of seconds specified in multi-line-timeout() passes, which results in syslog-ng PE sending the current message, which could be partial

NOTE: One Identity recommends that you set multi-line-timeout() to a higher value than (preferably a multiple of) follow-freq().

The recommended minimum value is 10 seconds.

pad-size()
Type: number
Default: 0

Description: Specifies input padding. Some operating systems (such as HP-UX) pad all messages to block boundary. This option can be used to specify the block size. The syslog-ng PE application will pad reads from the associated device to the number of bytes set in pad-size(). Mostly used on HP-UX where /dev/log is a named pipe and every write is padded to 2048 bytes. If pad-size() was given and the incoming message does not fit into pad-size(), syslog-ng will not read anymore from this pipe and displays the following error message:

Padding was set, and couldn't read enough bytes
program-override()
Type: string
Default:

Description: Replaces the ${PROGRAM} part of the message with the parameter string. For example, to mark every message coming from the kernel, include the program-override("kernel") option in the source containing /proc/kmsg.

tags()
Type: string
Default:

Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in syslog-ng 3.1 and later.

time-zone()
Type: name of the timezone, or the timezone offset
Default:

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 as using the name of the (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.

google-pubsub: collecting messages from the Google Pub/Sub messaging service

From version 7.0.22, syslog-ng Premium Edition (syslog-ng PE) can collect messages from the Google Pub/Sub messaging service using the google-pubsub() source.

NOTE: The rest of this section and its subsections assume that you are familiar with the Google Pub/Sub messaging service, and its concepts and terminology.

For more information about Google Pub/Sub's messaging service, see What Is Pub/Sub?.

For more information about setting up your Google Pub/Sub messaging service system, see Quickstart: building a functioning Pub/Sub system.

For more information about how the syslog-ng PE application sends logs to the Google Pub/Sub messaging service through the google_pubsub() destination, see google_pubsub: Sending logs to the Google Cloud Pub/Sub messaging service.

Caution:

This is a Preview Feature, which provides an insight to planned enhancements to functionality in the product. Consider this Preview Feature a work in progress, as it may not represent the final design and functionality.

This feature has completed QA release testing, but its full impact on production systems has not been determined yet, and potential future changes in functionality and the user interface may result in compatibility issues in your current settings.

One Identity recommends the following:

  • Consider the potential risks when using this functionality in a production environment.
  • Consider the Support Policy on Product Preview Features before using this functionality in a production environment.
  • Closely and regularly keep track of official One Identity announcements about potential changes in functionality and the user interface. If these potential changes affect your configuration, check the changes you have to make in your configuration, otherwise your syslog-ng PE application may not start after upgrade.
  • Always perform tests prior to upgrades in order to avoid the risks mentioned.

However, you are welcome to try this feature and if you have any feedback, Contact One Identity.

Support Policy on Product Preview Features

The One Identity Support Team will:

  • Accept and review each service request opened regarding a Preview Feature.

  • Consider all service requests relating to a Preview Features as severity level 3.

  • Provide best effort support to resolve any issues relating to a Preview Feature.

  • Work with customers to log any product defects or enhancements relating to Preview Features.

  • Not accept requests for escalations regarding Preview Features.

  • Not provide after-hours support for Preview Features.

Topics:

Prerequisites

To configure the google-pubsub() source on syslog-ng Premium Edition (syslog-ng PE), you must have each of the following:

Google Cloud Platform side prerequisites
Google Pub/Sub Subscription prerequisites
Example: Google Pub/Sub

The following example shows a Google Pub/Sub with all necessary parameters configured.

Figure 26: A Google Pub/Sub subscription with all necessary parameters configured

Limitations

The current implementation of the google-pubsub() source has the following limitations:

  • The At-Least-Once delivery behavior takes effect after creating your subscription.

    NOTE: The At-Least-Once delivery behavior (which means that if an error occurs, it is more acceptable to duplicate messages than to lose any of them) only takes effect after you create your Google Pub/Sub subscription.

    The At-Least-Once delivery behavior is intentional, and its purpose is to avoid potential log loss.

    For more information, see Preventing message duplication resulting from the At-Least-Once delivery behavior.

  • The Google Pub/Sub service cannot guarantee message ordering.

    As a result of the At-Least-Once delivery behavior, messages may be delivered out of order, especially if an outstanding message is not acknowledged by the subscriber before the Acknowledgement deadline passes. In this case, the Google Pub/Sub service will attempt to redeliver the message. As a result, the Google Pub/Sub service cannot guarantee message ordering.

  • The syslog-ng PE application retains acknowledgements on the source side and either acknowledges an ack-tracker-batch-size() number of messages in a batch, or sends acknowledgements after the ack-tracker-timeout() expires. If the value of your ack-tracker-timeout() is larger than the value of your Acknowledgement deadline, it may result in message duplication.

    NOTE: In case you encounter message duplication, One Identity recommends that you check the following parameters in your configuration:

    • log-fetch-limit(): if it set to a high value, it is possible that syslog-ng PE can not process the fetched messages within the configured Acknowledgement deadline.

    • ack-tracker-timeout(): if it set to a higher value than the Acknowledgement deadline configured on the Google Cloud Platform, set it to a lower value.

    For more information about message duplication, see Preventing message duplication resulting from the At-Least-Once delivery behavior.

Related Documents

The document was helpful.

Select Rating

I easily found the information I needed.

Select Rating