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syslog-ng Premium Edition 7.0.10 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng 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 wildcard-file: Collecting messages from multiple text files network: Collecting messages using the RFC3164 protocol (network() driver) osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes program: Receiving messages from external applications 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 unix-stream, unix-dgram: Collecting messages from UNIX domain sockets windowsevent: Collecting Windows event logs
Sending and storing log messages — destinations and destination drivers
elasticsearch: Sending messages directly to Elasticsearch version 1.x elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher file: Storing messages in plain-text files 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 smtp: Generating SMTP messages (e-mail) from logs Splunk: Sending log messages to Splunk sql: Storing messages in an SQL database syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng: Forwarding messages and tags 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 Parsers and segmenting 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 About us

smtp: Generating SMTP messages (e-mail) from logs

The destination is aimed at a fully controlled local, or near-local, trusted SMTP server. The goal is to send mail to trusted recipients, through a controlled channel. It hands mails over to an SMTP server, and that is all it does, therefore the resulting solution is as reliable as sending an e-mail in general. For example, syslog-ng PE does not verify whether the recipient exists.

The smtp() driver sends e-mail messages triggered by log messages. The smtp() driver uses SMTP, without needing external applications. You can customize the main fields of the e-mail, add extra headers, send the e-mail to multiple recipients, and so on.

The subject(), body(), and header() fields may include macros which get expanded in the e-mail. For more information on available macros see Macros of syslog-ng PE.

The smtp() driver has the following required parameters: host(), port(), from(), to(), subject(), and body(). For the list of available optional parameters, see smtp() destination options.

NOTE:

In order to use this destination, syslog-ng Premium Edition must run in server mode. Typically, only the central syslog-ng Premium Edition server uses this destination. For details on the server mode, see Server mode.

NOTE:

The smtp() destination driver is available only in 5 F2 and later.

Declaration:
smtp(host() port() from() to() subject() body() options());
Example: Using the smtp() driver

The following example defines an smtp() destination using only the required parameters.

destination d_smtp {
    smtp(
        host("localhost")
        port(25)
        from("syslog-ng alert service" "noreply@example.com")
        to("Admin #1" "admin1@example.com")
        subject("[ALERT] Important log message of $LEVEL condition received from $HOST/$PROGRAM!")
        body("Hi!\nThe syslog-ng alerting service detected the following important log message:\n $MSG\n-- \nsyslog-ng\n")
    );
};

The following example sets some optional parameters as well.

destination d_smtp {
    smtp(
        host("localhost")
        port(25)
        from("syslog-ng alert service" "noreply@example.com")
        to("Admin #1" "admin1@example.com")
        to("Admin #2" "admin2@example.com")
        cc("Admin BOSS" "admin.boss@example.com")
        bcc("Blind CC" "blindcc@example.com")
        subject("[ALERT] Important log message of $LEVEL condition received from $HOST/$PROGRAM!")
        body("Hi!\nThe syslog-ng alerting service detected the following important log message:\n $MSG\n-- \nsyslog-ng\n")
        header("X-Program", "$PROGRAM")
    );
};
Example: Simple e-mail alerting with the smtp() driver

The following example sends an e-mail alert if the eth0 network interface of the host is down.

filter f_linkdown {
    match("eth0: link down" value("MESSAGE"));
};
destination d_alert {
    smtp(
        host("localhost") port(25)
        from("syslog-ng alert service" "syslog@localhost")
        reply-to("Admins" "root@localhost")
        to("Ennekem" "me@localhost")
        subject("[SYSLOG ALERT]: eth0 link down")
        body("Syslog received an alert:\n$MSG")
    );
};

log {
    source(s_local);
    filter(f_linkdown);
    destination(d_alert);
};

smtp() destination options

The smtp() sends e-mail messages using SMTP, without needing external applications. The smtp() destination has the following options:

body()
Type: string
Default: n/a

Description: The BODY field of the e-mail. You can also use macros in the string. Use \n to start a new line. For example:

body("syslog-ng PE received the following alert from $HOST:\n$MSG")
bcc()
Type: string
Default: n/a

Description: The BCC recipient of the e-mail (contents of the BCC field). You can specify the e-mail address, or the name and the e-mail address. Set the bcc() option multiple times to send the e-mail to multiple recipients. For example: bcc("admin@example.com") or bcc("Admin" "admin@example.com") or bcc("Admin" "admin@example.com") bcc("Admin2" "admin2@example.com")

You can also use macros to set the value of this parameter.

cc()
Type: string
Default: n/a

Description: The CC recipient of the e-mail (contents of the CC field). You can specify the e-mail address, or the name and the e-mail address. Set the cc() option multiple times to send the e-mail to multiple recipients. For example: cc("admin@example.com") or cc("Admin" "admin@example.com") or cc("Admin" "admin@example.com") cc("Admin2" "admin2@example.com")

You can also use macros to set the value of this parameter.

disk-buffer()

Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:

reliable()
Type: yes|no
Default: no

Description: If set to yes, syslog-ng PE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng PE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.

Caution:

Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer, the messages stored in the disk-buffer will be lost.

dir()
Type: string
Default: N/A

Description: Defines the folder where the disk-buffer files are stored.

Caution:

When creating a new dir() option for a disk buffer, or modifying an existing one, make sure you delete the persist file.

syslog-ng PE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file is not deleted after modifying the dir() option, then following a restart, syslog-ng PE will look for or create disk-buffer files in their old location. To ensure that syslog-ng PE uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to.

disk-buf-size()
Type: number (bytes)
Default:

Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option.
mem-buf-length()
Type: number (messages)
Default: 10000
Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes.
mem-buf-size()
Type: number (bytes)
Default: 163840000
Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no.
qout-size()
Type: number (messages)
Default: 64
Description: The number of messages stored in the output buffer of the destination.

Options reliable() and disk-buf-size() are required options.

Example: Examples for using disk-buffer()

In the following case reliable disk-buffer() is used.

destination d_demo {
    network("127.0.0.1"
        port(3333)
        disk-buffer(
            mem-buf-size(10000)
            disk-buf-size(2000000)
            reliable(yes)
            dir("/tmp/disk-buffer")
        )
    );
};

In the following case normal disk-buffer() is used.

destination d_demo {
    network("127.0.0.1"
        port(3333)
        disk-buffer(
            mem-buf-length(10000)
            disk-buf-size(2000000)
            reliable(no)
            dir("/tmp/disk-buffer")
        )
    );
};
from()
Type: string
Default: n/a

Description: The sender of the e-mail (contents of the FROM field). You can specify the e-mail address, or the name and the e-mail address. For example:

from("admin@example.com")
or
from("Admin" "admin@example.com")

If you specify the from() option multiple times, the last value will be used. Instead of the from() option, you can also use sender(), which is just an alias of the from() option.

You can also use macros to set the value of this parameter.

header()
Type: string
Default: n/a

Description: Adds an extra header to the e-mail with the specified name and content. The first parameter sets the name of the header, the second one its value. The value of the header can contain macros. Set the header() option multiple times to add multiple headers. For example:

header("X-Program", "$PROGRAM")

When using the header option, note the following points:

  • Do not use the header() option to set the values of headers that have dedicated options. Use it only to add extra headers.

  • If you set the same custom header multiple times, only the first will be added to the e-mail, other occurrences will be ignored.

  • It is not possible to set the DATE, Return-Path, Original-Recipient, Content-*, MIME-*, Resent-*, Received headers.

host()
Type: hostname or IP address
Default: n/a

Description: Hostname or IP address of the SMTP server.

NOTE:

If you specify host="localhost", syslog-ng PE will use a socket to connect to the local SMTP server. Use host="127.0.0.1" to force TCP communication between syslog-ng PE and the local SMTP server.

log-fifo-size()
Type: number
Default: Use global setting.

Description: The number of messages that the output queue can store.

port()
Type: number
Default: 25

Description: The port number of the SMTP server.

reply-to()
Type: string
Default: n/a

Description: Replies of the recipient will be sent to this address (contents of the REPLY-TO field). You can specify the e-mail address, or the name and the e-mail address. Set the reply-to() option multiple times to send the e-mail to multiple recipients. For example: reply-to("admin@example.com") or reply-to("Admin" "admin@example.com") or reply-to("Admin" "admin@example.com") reply-to("Admin2" "admin2@example.com")

You can also use macros to set the value of this parameter.

retries()
Type: number (of attempts)
Default: 3

Description: The number of times syslog-ng PE attempts to send a message to this destination. If syslog-ng PE could not send a message, it will try again until the number of attempts reaches retries, then drops the message.

subject()
Type: string
Default: n/a

Description: The SUBJECT field of the e-mail. You can also use macros. For example:

subject("[SYSLOG ALERT]: Critical error message received from $HOST")

If you specify the subject() option multiple times, the last value will be used.

throttle()
Type: number
Default: 0

Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using disk-buffer as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.

to()
Type: string
Default: localhost

Description: The recipient of the e-mail (contents of the TO field). You can specify the e-mail address, or the name and the e-mail address. Set the to() option multiple times to send the e-mail to multiple recipients. For example: to("admin@example.com") or to("Admin" "admin@example.com") or to("Admin" "admin@example.com") to("Admin2" "admin2@example.com")

You can also use macros to set the value of this parameter.

Splunk: Sending log messages to Splunk

Although syslog-ng PE currently does not have any built-in integration with Splunk, the existing message-formatting features and flexibility of syslog-ng PE allows you to forward your log messages to Splunk. In syslog-ng PE version 7.0.4 or later, you can use the http() destination. In earlier versions, you can use the program() destination.

For details on forwarding log messages to Splunk with syslog-ng PE see the following posts on the Splunk blog:

sql: Storing messages in an SQL database

The sql() driver sends messages into an SQL database. Currently the Microsoft SQL (MSSQL), MySQL, Oracle, PostgreSQL, and SQLite databases are supported.

NOTE:

In order to use this destination, syslog-ng Premium Edition must run in server mode. Typically, only the central syslog-ng Premium Edition server uses this destination. For details on the server mode, see Server mode.

Declaration:
sql(database_type host_parameters database_parameters [options]);

The sql() driver has the following required parameters: type(), database(), table(), columns(), and values().

Caution:

The syslog-ng application requires read and write access to the SQL table, otherwise it cannot verify that the destination table exists.

Currently the syslog-ng application has default schemas for the different databases and uses these defaults if the database schema (for example columns and column types) is not defined in the configuration file. However, these schemas will be deprecated and specifying the exact database schema will be required in later versions of syslog-ng.

NOTE:

In addition to the standard syslog-ng packages, the sql() destination requires database-specific packages to be installed. These packages are automatically installed by the binary syslog-ng installer.

The sql() driver is currently not available for every platform that is supported by syslog-ng. For a list of platforms that support the sql() driver, visit this link.

The table and value parameters can include macros to create tables and columns dynamically (for details, see Macros of syslog-ng PE).

Caution:

When using macros in table names, note that some databases limit the maximum allowed length of table names. Consult the documentation of the database for details.

Inserting the records into the database is performed by a separate thread. The syslog-ng application automatically performs the escaping required to insert the messages into the database.

Example: Using the sql() driver

The following example sends the log messages into a PostgreSQL database running on the logserver host. The messages are inserted into the logs database, the name of the table includes the exact date and the name of the host sending the messages. The syslog-ng application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges.

destination d_sql {
    sql(
        type(pgsql)
        host("logserver")
        username("syslog-ng")
        password("password")
        database("logs")
        table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
        columns("datetime", "host", "program", "pid", "message")
        values("{$R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
        indexes("datetime", "host", "program", "pid", "message")
    );
};

The following example specifies the type of the database columns as well:

destination d_sql {
    sql(
        type(pgsql)
        host("logserver")
        username("syslog-ng")
        password("password")
        database("logs")
        table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
        columns("datetime varchar(16)", "host varchar(32)", "program  varchar(20)", "pid varchar(8)", "message  varchar(200)")
        values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
        indexes("datetime", "host", "program", "pid", "message")
    );
};
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