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syslog-ng Premium Edition 6.0.17 - Administration Guide

Preface Chapter 1. Introduction to syslog-ng Chapter 2. The concepts of syslog-ng Chapter 3. Installing syslog-ng Chapter 4. The syslog-ng PE quick-start guide Chapter 5. The syslog-ng PE configuration file Chapter 6. Collecting log messages — sources and source drivers Chapter 7. Sending and storing log messages — destinations and destination drivers Chapter 8. Routing messages: log paths, reliability, and filters Chapter 9. Global options of syslog-ng PE Chapter 10. TLS-encrypted message transfer Chapter 11. FIPS-compliant syslog-ng Chapter 12.  Reliable Log Transfer Protocol™ Chapter 13. Reliability and minimizing the loss of log messages Chapter 14. Manipulating messages Chapter 15. Parsing and segmenting structured messages Chapter 16. Processing message content with a pattern database Chapter 17. Statistics and metrics of syslog-ng Chapter 18. Multithreading and scaling in syslog-ng PE Chapter 19. Troubleshooting syslog-ng Chapter 20. Best practices and examples

Sending messages to external applications

The program() driver starts an external application or script and sends the log messages to its standard input (stdin). Usually, every message is a single line (ending with a newline character), which your script can process. Make sure that your script runs in a loop and keeps reading the standard input — it should not exit. (If your script exits, syslog-ng PE tries to restart it.)

The program() driver has a single required parameter, specifying a program name to start. The program is executed with the help of the current shell, so the command may include both file patterns and I/O redirections. For the list of available optional parameters, see the section called “program() destination options”.

Caution:

This feature is currently not available when running the syslog-ng PE application on Microsoft Windows platforms. For a complete list of limitations, see the section called “Limitations on Microsoft Windows platforms”.

Declaration: 

program(command_to_run);

NOTE:
  • The syslog-ng PE application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor, you might have to modify your AppArmor configuration to enable syslog-ng PE to execute external applications.

  • The syslog-ng PE application executes program destinations through the standard system shell. If the system shell is not bash and you experience problems with the program destination, try changing the /bin/sh link to /bin/bash.

  • If the external program exits, the syslog-ng PE application automatically restarts it. However it is not recommended to launch programs for single messages, because if the message rate is high, launching several instances of an application might overload the system, resulting in Denial of Service.

  • When the syslog-ng PE application stops, it will automatically stop the external program. To avoid restarting the application when syslog-ng PE is only reloaded, enable the keep-alive() option in the program destination.

  • Certain external applications buffer the log messages, which might cause unexpected latency and other problems. For example, if you send the log messages to an external Perl script, Perl uses a line buffer for terminal output and block buffer otherwise. You might want to disable buffering in the external application.

Example 7.26. Using the program() destination driver

The message format does not include the priority and facility values by default. To add these values, specify a template for the program destination, as shown in the following example. Make sure to end your template with a newline character (\n).

destination d_prog { program("/bin/script" template("<${PRI}>${DATE} ${HOST} ${MSG}\n") ); };

The following shell script writes the incoming messages into the /tmp/testlog file.

#!/bin/bash
while read line ; do
echo $line >> /tmp/testlog
done

program() destination options

Caution:

This feature is currently not available when running the syslog-ng PE application on Microsoft Windows platforms. For a complete list of limitations, see the section called “Limitations on Microsoft Windows platforms”.

This driver starts an external application or script and sends the log messages to its standard input (stdin).

The program() destination has the following options:

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. This option has priority over --qdisk-dir=.

Caution:

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

syslog-ng PE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file or the relevant entry 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.
quot-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 7.27. 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")
            )
        );
};

flags()
Type: no_multi_line, syslog-protocol
Default: empty set

Description: Flags influence the behavior of the destination driver.

  • no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line.

  • syslog-protocol: The syslog-protocol flag instructs the driver to format the messages according to the new IETF syslog protocol standard (RFC5424), but without the frame header. If this flag is enabled, macros used for the message have effect only for the text of the message, the message header is formatted to the new standard. Note that this flag is not needed for the syslog driver, and that the syslog driver automatically adds the frame header to the messages.

flush-lines()
Type: number (messages)
Default: Use global setting.

Description: Specifies how many lines are sent to a destination at a time. The syslog-ng PE application waits for this number of lines to accumulate and sends them off in a single batch. Setting this number high increases throughput as fully filled frames are sent to the destination, but also increases message latency.

For optimal performance when sending messages to an syslog-ng PE server, make sure that the flush-lines() is smaller than the window size set using the log-iw-size() option in the source of your server.

flush-timeout() (OBSOLETE)
Type: time in milliseconds
Default: Use global setting.

Description: This is an obsolete option. Specifies the time syslog-ng waits for lines to accumulate in its output buffer. For details, see the flush-lines() option.

NOTE:

This option will be removed from the list of acceptable options. After that, your configuration will become invalid if it still contains the flush-timeout() option. To avoid future problems, remove this option from your configuration.

frac-digits()
Type: number (digits of fractions of a second)
Default: Value of the global option (which defaults to 0)

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

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

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

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

Description: Specifies whether the external program should be closed when syslog-ng PE is reloaded.

mark-freq()
Accepted values: number (seconds)
Default: 1200

Description: An alias for the obsolete mark() option, retained for compatibility with syslog-ng version 1.6.x. The number of seconds between two MARK messages. MARK messages are generated when there was no message traffic to inform the receiver that the connection is still alive. If set to zero (0), no MARK messages are sent. The mark-freq() can be set for global option and/or every MARK capable destination driver if mark-mode() is periodical or dst-idle or host-idle. If mark-freq() is not defined in the destination, then the mark-freq() will be inherited from the global options. If the destination uses internal mark-mode(), then the global mark-freq() will be valid (does not matter what mark-freq() set in the destination side).

mark-mode()
Accepted values: internal | dst-idle | host-idle | periodical | none | global
Default:

internal for pipe, program drivers

none for file, unix-dgram, unix-stream drivers

global for syslog, tcp, udp destinations

host-idle for global option

Description: The mark-mode() option can be set for the following destination drivers: file(), program(), unix-dgram(), unix-stream(), network(), pipe(), syslog() and in global option.

  • internal: When internal mark mode is selected, internal source should be placed in the log path as this mode does not generate mark by itself at the destination. This mode only yields the mark messages from internal source. This is the mode as syslog-ng PE 3.x worked. MARK will be generated by internal source if there was NO traffic on local sources:

    file(), pipe(), unix-stream(), unix-dgram(), program()

  • dst-idle: Sends MARK signal if there was NO traffic on destination drivers. MARK signal from internal source will be dropped.

    MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().

  • host-idle: Sends MARK signal if there was NO local message on destination drivers. For example MARK is generated even if messages were received from tcp. MARK signal from internal source will be dropped.

    MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().

  • periodical: Sends MARK signal perodically, regardless of traffic on destination driver. MARK signal from internal source will be dropped.

    MARK signal can be sent by the following destination drivers: network(), syslog(), program(), file(), pipe(), unix-stream(), unix-dgram().

  • none: Destination driver drops all MARK messages. If an explicit mark-mode() is not given to the drivers where none is the default value, then none will be used.

  • global: Destination driver uses the global mark-mode() setting. The syslog-ng interprets syntax error if the global mark-mode() is global.

NOTE:

In case of dst-idle, host-idle and periodical, the MARK message will not be written in the destination, if it is not open yet.

Available in syslog-ng PE 4 LTS and later.

suppress()
Type: seconds
Default: 0 (disabled)

Description: If several identical log messages would be sent to the destination without any other messages between the identical messages (for example, an application repeated an error message ten times), syslog-ng can suppress the repeated messages and send the message only once, followed by the Last message repeated n times. message. The parameter of this option specifies the number of seconds syslog-ng waits for identical messages.

template()
Type: string
Default: A format conforming to the default logfile format.

Description: Specifies a template defining the logformat to be used in the destination. Macros are described in the section called “Macros of syslog-ng PE. Please note that for network destinations it might not be appropriate to change the template as it changes the on-wire format of the syslog protocol which might not be tolerated by stock syslog receivers (like syslogd or syslog-ng itself). For network destinations make sure the receiver can cope with the custom format defined.

Make sure to end your template with a newline character (\n).

template-escape()
Type: yes or no
Default: no

Description: Turns on escaping for the ', ", and backspace characters in templated output files. This is useful for generating SQL statements and quoting string contents so that parts of the log message are not interpreted as commands to the SQL server.

throttle()
Type: number (messages per second)
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.

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

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see the section called “Date-related macros”.

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.

ts-format()
Type: rfc3164, bsd, rfc3339, iso
Default: Use the global option (which defaults to rfc3164)

Description: Override the global timestamp format (set in the global ts-format() parameter) for the specific destination. For details, see the section called “A note on timezones and timestamps”.

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 the section called “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 the section called “smtp() destination options”.

NOTE:

Windows platforms are not supported. Mark mode is not supported at all, if SMTP receives a mark message, it will drop the message.

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

Declaration: 

smtp(from() to() subject() body() options());

Example 7.28. 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 7.29. 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")
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")
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. This option has priority over --qdisk-dir=.

Caution:

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

syslog-ng PE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file or the relevant entry 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.
quot-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 7.30. 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")
            )
        );
};

frac-digits()
Type: number (digits of fractions of a second)
Default: Value of the global option (which defaults to 0)

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

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.

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 (messages)
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")
retries()
Type: number
Default: 3

Description: Number of times a message send operation is retried upon failure.

sender()
Type: string
Default: n/a

Description: An alias for the from() option

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 (messages per second)
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.

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

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see the section called “Date-related macros”.

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.

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")

Error handling

If the connection fails, syslog-ng PE repeatedly attempts to reconnect in intervals specified in time-reopen().

If the connection is successful, but the message is not accepted, syslog-ng PE attempts to resend the message N times regardless of the reject being a hard or a soft reject. The number of attempts is specified with the option retries().

NOTE:

If the message was sent to two addresses and only one address fails, the retry will still apply for both addresses. The assumption is that the destination will be used with a local SMTP server acting as a relay, and the local server will handle all the edge cases.

Sending SNMP traps

The snmp() driver sends SNMP traps using the Simple Network Management Protocol version 2c or version 3. Incoming log messages can be converted to SNMP traps, as the fields of the SNMP messages can be customized using syslog-ng PE macros.

NOTE:

The snmp() driver is available in syslog-ng PE version 4 F1 and later.

NOTE:

The snmp destination driver currently supports sending SNMP traps only using the UDP transport protocol.

The snmp() driver requires the host(), trap-obj(), and snmp-obj() options to be set, as well as the engine-id() option in case the SNMPv3 protocol is used. For the list of available optional parameters, see the section called “snmp() destination options”.

Declaration: 

@module snmp
        destination d_snmp {snmp(host() trap-obj() snmp-obj() ...);};

By default, syslog-ng PE does not load the snmp() module. If you want to use the snmp() destination, include the following line in your syslog-ng PE configuration file before defining the destination to load the snmp() module. This line is needed only once, even if you use multiple SNMP destinations. For details on modules, see the section called “Loading modules”.

@module snmp

Caution:

If syslog-ng PE cannot resolve the destination hostname during startup, it will try to resolve the hostname again when the next message to be sent as an SNMP trap is received. However, if this name resolution fails, the trap will be dropped.

NOTE:

The snmp() destination driver does not generate MARK signals itself, but can receive and forward MARK signals.

Example 7.31. Using the snmp() destination driver

The following example defines an SNMP destination that uses the SNMPv2c protocol.

@module snmp

destination d_snmpv2c{
    snmp(
        version('v2c')
        host('192.168.1.1')
        trap-obj('.1.3.6.1.6.3.1.1.4.1.0', 'Objectid', '.1.3.6.1.4.1.18372.3.1.1.1.2.1')
        snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.1.0', 'Octetstring', 'Test SNMP trap')
        snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.2.0', 'Octetstring', 'admin')
        snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.3.0', 'Ipaddress', '192.168.1.1')
        );
};

The following example defines an SNMP destination that uses the SNMPv3 protocol and uses macros to fill the values of the SNMP objects.

@module snmp

destination d_snmpv3{
    snmp(
        version('v3')
        host('192.168.1.1')
        port(162)
        engine-id('0xdeadbeefde')
        auth-username('myusername')
        auth-password('password')
        enc-algorithm('AES')
        enc-password('password')
        trap-obj('.1.3.6.1.6.3.1.1.4.1.0', 'Objectid', '.1.3.6.1.4.1.18372.3.1.1.1.2.1')
        snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.1', 'Octetstring', '${MESSAGE}')
        snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.2', 'Octetstring', 'admin')
        snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.3', 'Ipaddress', '${SOURCEIP}')
        );
};

Converting Cisco syslog messages to "clogMessageGenerated" SNMP traps

Starting with version 4 F1, syslog-ng PE can convert the syslog messages sent by Cisco devices to Cisco-specific SNMP traps defined by the CISCO-SYSLOG-MIB (enterprises.cisco.ciscoMgmt.ciscoCiscoMIB) is also supported (such traps are also referred to as clogMessageGenerated notifications). That way, the incoming log messages can be forwarded to devices used to process and analyze Cisco-specific SNMP traps. For this to work correctly, the following requirements must be met:

  • The snmp module of syslog-ng PE must be loaded, that is, the syslog-ng PE configuration file must include the following line:

    @module snmp
  • The syslog-ng Source Configuration Library (SCL) must be included in the syslog-ng PE configuration file:

    @include "scl.conf"
  • The pattern database described in the section called “Parsing Cisco-specific message fields with patterndb” must be used to parse the incoming log messages.

To accomplish this, syslog-ng PE has to use a special pattern database to parse the Cisco-specific syslog messages, because these messages do not comply with the standard syslog formats.

For details on the Cisco-specific SNMP trap format, see CISCO-SYSLOG-MIB on the Cisco website.

Parsing Cisco-specific message fields with patterndb

The ${PROGRAM} part of the syslog messages sent by Cisco devices contain not only the program name, but other important protocol information part as well. The ${PROGRAM} of these messages contains the Facility, Severity, and the Mnemonic (the Cisco name) of the message. The following pattern database parses these values and makes them available as the .cisco.Facility, .cisco.Severity, and .cisco.MsgName, respectively. The actual log message is available as .cisco.MsgText.

<patterndb version="4" pub_date="2011-05-03">  <ruleset name="cisco snmp ruleset1" xml:id="480de478-d4a6-4a7f-bea4-0c0245d361e3">    <description>Pattern for Cisco messages having BSD timestamps, for example: Jul 01 2010 00:32:59: %SYS-5-CONFIG_I: Configured from console by console</description>    <url>http://balabit.com</url>      <pattern>%@ESTRING:.cisco.Facility:-@@ESTRING:.cisco.Severity:-@@ANYSTRING:.cisco.MsgName@</pattern>        <rules>          <rule xml:id="09944c71-95eb-4bc0-8575-936931d85713" provider="balabit" class="system">            <patterns>              <pattern> @ANYSTRING:.cisco.MsgText@</pattern>              </patterns>          </rule>        </rules>  </ruleset>  <ruleset name="cisco snmp ruleset2" xml:id="480de478-d4a6-4a7f-bea4-0c0245d361e3">    <description>Pattern for Cisco messages having cisco-specific timestamps, for example: 18: Jan 22 10:45:44.543: %SYS-5-CONFIG_I: Configured from console by console</description>    <url>http://balabit.com</url>        <rules>          <rule xml:id="09944c71-95eb-4bc0-8575-936931d85714" provider="balabit" class="system">            <patterns>              <pattern>%@ESTRING:.cisco.Facility:-@@ESTRING:.cisco.Severity:-@@ESTRING:.cisco.MsgName::@ @ANYSTRING:.cisco.MsgText@</pattern>             </patterns>          </rule>        </rules>  </ruleset></patterndb>

Sending clogMessageGenerated SNMP traps

To send out clogMessageGenerated SNMP traps, use the cisco_snmp() destination driver. The cisco-snmp() destination is actually a modified version of the snmp() destination driver.

NOTE:

The cisco-snmp() driver is actually an element of the syslog-ng Source Configuration Library (SCL), a reusable configuration snippet tailored to handle process accounting logs. For details on using or writing SCLs, see the section called “Reusing configuration blocks”.

The cisco-snmp() driver has the same requirements and options as the snmp() destination driver, but automatically fills the clogMessageGenerated-specific fields with the data received from parsing the Cisco-specific syslog messages using the pattern database. For details on the , see the <INSTALLDIR>/ share/include/scl/snmp/plugin.conf file.

Declaration: 

destination d_cisco_snmp {cisco-snmp(host(<hostname>));};

Example 7.32. Defining a Cisco-specific SNMP destination

The following example defines an SNMP destination that sends out clogMessageGenerated messages using the SNMPv3 protocol.

destination d_cisco_snmp {cisco-snmp(host("192.168.1.1")
version("v3")
engine-id("'0xdeadbeefde'")
auth-username('myusername')
auth-password('password')
enc-password('password'));};

snmp() destination options

This driver sends SNMP traps using the SNMP v2c or v3 protocol.

The snmp() destination has the following options:

auth-algorithm()
Type: SHA|sha
Default: SHA

Description: The authentication method to use. Lowercase values (for example, sha) can be used as well.

This option is used with the SNMPv3 protocol.

auth-password()
Type: string
Default: empty string

Description: The password used for authentication. If the auth-username() option is set but the auth-password() is empty, syslog-ng PE will try to authenticate with an empty password.

This option is used with the SNMPv3 protocol.

auth-username()
Type: string
Default:

Description: The username used to authenticate on the SNMP server. If this parameter is set, syslog-ng PE will try to authenticate on the SNMP server.

This option is used with the SNMPv3 protocol.

community()
Type: string
Default: public

Description: The community string used for SNMPv2c authentication.

This option is used with the SNMPv2c protocol.

enc-algorithm()
Type: AES|aes
Default: AES

Description: The encryption method used to encrypt the SNMP traffic. Lowercase values (for example, aes) can be used as well.

This option is used with the SNMPv3 protocol.

enc-password()
Type: string
Default:

Description: The password used for the encryption. Encryption is used only if the enc-password() is not empty.

This option is used with the SNMPv3 protocol.

engine-id()
Type: number (hexadecimal number)
Default:

Description: The engine ID is a hexadecimal number at least 10 digits long, starting with 0x. For example 0xABABABABAB.

This option is a required parameter when using the SNMPv3 protocol.

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

Description: Hostname of the SNMP server.

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

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

port()
Type: number (port number)
Default: 162

Description: The port number to connect to.

snmp-obj()
Type: <oid_of_the_object>, <type_of_the_object>, <value_of_the_object>
Default:

Description: The snmp-obj() option can be used to create custom SNMP trap elements. To create a trap element, specify the OID, type, and value of the element in the snmp-obj() option. To send SNMP traps, at least one snmp-obj() option must be defined. The snmp-obj() option requires the following parameters. Note that syslog-ng PE does not validate the values of these elements.

  • <oid_of_the_object>: The object id of the SNMP object, for example, .1.3.6.1.4.1.18372.3.1.1.1.1.1.

  • <type_of_the_object>: The type of the object specified as an ASN.1 primitive. One of: Integer, Timeticks, Octetstring, Counter32, Ipaddress, Objectid. The type names are not case sensitive.

  • <value_of_the_object>: The value of the object as a string. The macros of syslog-ng PE can be used to set these values, making it possible to transfer the content and other metadata from the the syslog message to the SNMP trap. Note that if the value of an Integer, Counter32 or Timeticks object is not a number (for example, is an empty string or other not-number string), syslog-ng PE will automatically replace the value with 0. The values of other types of objects are not validated.

Example 7.33. Defining SNMP objects

The following are SNMP object definitions:

snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.3', 'Ipaddress', '192.168.1.1')
snmp-obj('.1.3.6.1.4.1.18372.3.1.1.1.1.2', 'Octetstring', '${MESSAGE}')

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

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see the section called “Date-related macros”.

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.

trap-obj()
Type: <oid_of_the_object>, "Objectid", <value_of_the_object>
Default:

Description: The trap-obj() is a specialized version of the snmp-obj() option that is used to identify the SNMP trap object. The type of the trap object is always Objectid. The <oid_of_the_object> and the <value_of_the_object> parameters are identical to the respective parameters of the snmp-obj() option. For details on these parameters, see the section called “snmp-obj()”.

NOTE:

Using the trap-obj() object is equivalent to using the snmp-obj() with the Objectid type.

version()
Type: v2c|v3
Default: v2c

Description: Specifies which version of the SNMP protocol to use.

NOTE:

The syslog-ng PE application will accept any valid option for the snmp() destination, but will only use the ones relevant to the selected protocol version, any other option will be ignored. For example, if the version("v2c") engine-id("0xABABABABAB") community("mycommunity") options are set, syslog-ng PE will accept every option, but process only the community() option, because engine-id() applies only to SNMPv3.

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 the section called “Server mode”.

Caution:

This feature is currently not available when running the syslog-ng PE application on Microsoft Windows platforms. For a complete list of limitations, see the section called “Limitations on Microsoft Windows platforms”.

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 the section called “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 7.34. 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"));
};

Using the sql() driver with an Oracle database

The Oracle sql destination has some special aspects that are important to note.

  • The hostname of the database server is set in the tnsnames.ora file, not in the host parameter of the sql() destination.

    If the tnsnames.ora file is not located in the /etc directory (or in the /var/opt/oracle directory on Solaris), set the following Oracle-related environment variables, so syslog-ng PE will find the file: ORACLE_BASE, ORACLE_HOME, and ORACLE_SID. For details, see the documentation of the Oracle Instant Client.

  • You cannot use the same database() settings in more than one destination, because the database() option of the SQL driver is just a reference to the connection string of the tnsnames.ora file. To overcome this problem, you can duplicate the connections in the tnsnames.ora file under a different name, and use a different table in each Oracle destination in syslog-ng PE.

  • As certain database versions limit the maximum length of table names, macros in the table names should be used with care.

  • In the current version of syslog-ng PE, the types of database columns must be explicitly set for the Oracle destination. The column used to store the text part of the syslog messages should be able to store messages as long as the longest message permitted by syslog-ng, therefore it is usually recommended to use the varchar2 or clob column type. (The maximum length of the messages can be set using the log-msg-size() option.) For details, see the following example.

  • The Oracle Instant Client used by syslog-ng PE supports only the following character sets:

    • Single-byte character sets: US7ASCII, WE8DEC, WE8MSWIN1252, and WE8ISO8859P1

    • Unicode character sets: UTF8, AL16UTF16, and AL32UTF8

Example 7.35. Using the sql() driver with an Oracle database

The following example sends the log messages into an Oracle database running on the logserver host, which must be set in the /etc/tnsnames.ora file. The messages are inserted into the LOGS database, the name of the table includes the exact date when the messages were sent. 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(oracle)
  username("syslog-ng") password("password")
  database("LOGS")
  table("msgs_${R_YEAR}${R_MONTH}${R_DAY}")
  columns("datetime varchar(16)", "host varchar(32)", "program varchar(32)", "pid varchar(8)", "message varchar2")
  values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
  indexes("datetime", "host", "program", "pid", "message"));
};

The Oracle Instant Client retrieves the address of the database server from the /etc/tnsnames.ora file. Edit or create this file as needed for your configuration. A sample is provided below.

LOGS =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)
(HOST = logserver)
(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = EXAMPLE.SERVICE)
)
)

Using the sql() driver with a Microsoft SQL database

The mssql database driver can access Microsoft SQL (MSSQL) destinations. This driver has some special aspects that are important to note.

  • The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. For details, see the following example.

  • As certain database versions limit the maximum length of table names, macros in the table names should be used with care.

  • In the current version of syslog-ng PE, the types of database columns must be explicitly set for the MSSQL destination.

    Caution:

    The following column types cannot be used in MSSQL destinations: nchar, nvarchar, ntext, and xml.

  • The column used to store the text part of the syslog messages should be able to store messages as long as the longest message permitted by syslog-ng. The varchar column type can store maximum 4096 bytes-long messages. The maximum length of the messages can be set using the log-msg-size() option. For details, see the following example.

  • Remote access for SQL users must be explicitly enabled on the Microsoft Windows host running the Microsoft SQL Server. For details, see Procedure 3.12, “Configuring Microsoft SQL Server to accept logs from syslog-ng”.

Example 7.36. Using the sql() driver with an MSSQL database

The following example sends the log messages into an MSSQL database running on the logserver host. The messages are inserted into the syslogng database, the name of the table includes the exact date when the messages were sent. 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_mssql {
sql(type(mssql) host("logserver") port("1433")
  username("syslogng") password("syslogng") database("syslogng")
  table("msgs_${R_YEAR}${R_MONTH}${R_DAY}")columns("datetime varchar(16)", "host varchar(32)",
  "program varchar(32)", "pid varchar(8)", "message varchar(4096)")
  values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
  indexes("datetime", "host", "program", "pid"));
};

The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. Edit or create this file as needed for your configuration. A sample is provided below.

[default]
date = "%Y-%m-%d %H:%M:%S"

The way syslog-ng interacts with the database

Used SQL operations by syslog-ng. 

Create table:

  • If the given table does not exist, syslog-ng tries to create it with the given column types.

  • The syslog-ng PE application automatically creates the required tables and columns, if the user account used to connect to the database has the required privileges.

  • If syslog-ng cannot create or alter a table, it tries to do it again when it reaches the next time-reopen().

Alter table:

  • If the table structure is different from given structure in an existing table, syslog-ng tries to add columns in this table but never will delete or modify an existing column.

  • If syslog-ng PE cannot create or alter a table, it tries to do it again when reach the next time-reopen().

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

Insert table:

  • Insert new records in a table.

  • Inserting the records into the database is performed by a separate thread.

  • The syslog-ng PE application automatically performs the escaping required to insert the messages into the database.

  • If insert returns with error, syslog-ng tries to insert the message +two times by default, then drops it. Retrying time is the value of time-reopen().

Encoding. 

The syslog-ng PE application uses UTF-8 by default when writes logs into database.

Start/stop and reload. 

Start:

  • The syslog-ng PE application will connect to database automatically after starting regardless existing incoming messages.

Stop:

  • The syslog-ng PE application will close the connection to database before shutting down.

Possibility of losing logs:

  • The syslog-ng PE application cannot lose logs during shutting down if disk buffer was given and it is not full yet.

  • The syslog-ng PE application cannot lose logs during shutting down if disk buffer was not given.

Reload:

  • The syslog-ng PE application will close the connection to database if it received SIGHUP signal (reload).

  • It will reconnect to the database when it tries to send a new message to this database again.

Macros: 

The value of ${SEQNUM} macro will be overrided by sql driver regardless of local or relayed incoming message.

It will be grown continously.

MySQL-specific interaction methods

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.

MsSQL-specific interaction methods

In SQL Server 2005 this restriction is lifted - kind of. The total length of all key columns in an index cannot exceed 900 bytes.

If you are using null() in your configuration, be sure that the columns allow NULL to insert. Give the column as the following example: "datetime varchar(16) NULL".

The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. [default] date = "%Y-%m-%d %H:%M:%S".

Supported SQL destinations by platform

Table 7.2. Supported SQL destinations by platform

Platform \ Database MSSQL MySQL PgSQL SQLite Oracle
AIX -
Linux (linux_glibc236): CentOS 5
Linux (linux_glibc236): CentOS 6
Linux (linux_glibc236): CentOS 7
Linux (linux_glibc236): Debian 7
Linux (linux_glibc236): openSUSE 11
Linux (linux_glibc236): Oracle Linux 5
Linux (linux_glibc236): Oracle Linux 6
Linux (linux_glibc236): Oracle Linux 7
Linux (linux_glibc236): SLES 11
Linux (linux_glibc236): Red Hat EL 5
Linux (linux_glibc236): Red Hat EL 6
Linux (linux_glibc236): Red Hat EL 7
Linux (linux_glibc236): Ubuntu 12.04
Linux (linux_glibc236): Ubuntu 14.04
FreeBSD 8 -
FreeBSD 9 -
FreeBSD 10 -
HP-UX 11v2_on IA64 -
Solaris 10 on SPARC and SPARC64
Solaris 11 on SPARC and SPARC64
Solaris 10 on x86_64 -
Solaris 11 on x86_64 -

sql() 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 the section called “Server mode”.

Caution:

This feature is currently not available when running the syslog-ng PE application on Microsoft Windows platforms. For a complete list of limitations, see the section called “Limitations on Microsoft Windows platforms”.

This driver sends messages into an SQL database. The sql() destination has the following options:

columns()
Type: string list
Default: "date", "facility", "level", "host", "program", "pid", "message"

Description: Name of the columns storing the data in fieldname [dbtype] format. The [dbtype] parameter is optional, and specifies the type of the field. By default, syslog-ng PE creates text columns. Note that not every database engine can index text fields.

Caution:

The following column types cannot be used in MSSQL destinations: nchar, nvarchar, ntext, and xml.

database()
Type: string
Default: logs

Description: Name of the database that stores the logs. Macros cannot be used in database name. Also, when using an Oracle database, you cannot use the same database() settings in more than one destination.

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. This option has priority over --qdisk-dir=.

Caution:

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

syslog-ng PE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file or the relevant entry 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.
quot-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 7.37. 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")
            )
        );
};

flags()
Type: list of flags
Default: empty string

Description: Flags related to the sql() destination.

  • dont-create-tables: Enable this flag to prevent syslog-ng PE from creating non-existing database tables automatically. The syslog-ng PE application typically has to create tables if you use macros in the table names. Available in syslog-ng PE version 4.0 and later.

  • explicit-commits: By default, syslog-ng PE commits every log message to the target database individually. When the explicit-commits option is enabled, messages are committed in batches. This improves the performance, but results in some latency, as the messages are not immediately sent to the database. The size and frequency of batched commits can be set using the flush-lines() parameter. The explicit-commits option is available in syslog-ng PE version 4.0 and later.

Example 7.38. Setting flags for SQL destinations

The following example sets the dont-create-tables and explicit-commits flags for an sql() destination.

flags(dont-create-tables,explicit-commits)

flush-lines()
Type: number (messages)
Default: Use global setting.

Description: Specifies how many lines are sent to a destination at a time. The syslog-ng PE application waits for this number of lines to accumulate and sends them off in a single batch. Setting this number high increases throughput as fully filled frames are sent to the destination, but also increases message latency.

For optimal performance when sending messages to an syslog-ng PE server, make sure that the flush-lines() is smaller than the window size set using the log-iw-size() option in the source of your server.

flush-timeout() (OBSOLETE)
Type: time in milliseconds
Default: Use global setting.

Description: This is an obsolete option. Specifies the time syslog-ng waits for lines to accumulate in its output buffer. For details, see the flush-lines() option.

NOTE:

This option will be removed from the list of acceptable options. After that, your configuration will become invalid if it still contains the flush-timeout() option. To avoid future problems, remove this option from your configuration.

frac-digits()
Type: number (digits of fractions of a second)
Default: Value of the global option (which defaults to 0)

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

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

Description: Hostname of the database server. Note that Oracle destinations do not use this parameter, but retrieve the hostname from the /etc/tnsnames.ora file.

NOTE:

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

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.

indexes()
Type: string list
Default: "date", "facility", "host", "program"

Description: The list of columns that are indexed by the database to speed up searching. To disable indexing for the destination, include the empty indexes() parameter in the destination, simply omitting the indexes parameter will cause syslog-ng to request indexing on the default columns.

The syslog-ng PE application will create the name of indexes automaticaly with the following method:

  • In case of MsSQL, PostgreSQL, MySQL or SQLite or (Oracle but tablename < 30 characters): {table}_{column}_idx.

  • In case of Oracle and tablename > 30 characters: md5sum of {table}_{column}-1 and the first character will be replaced by "i" character and the md5sum will be truncated to 30 characters.

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

Description: Sets the timezone used when expanding filename and tablename templates.

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.

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

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

null()
Type: string
Default:

Description: If the content of a column matches the string specified in the null() parameter, the contents of the column will be replaced with an SQL NULL value. If unset (by default), the option does not match on any string. For details, see the Example 7.39, “Using SQL NULL values”.

Example 7.39. Using SQL NULL values

The null() parameter of the SQL driver can be used to replace the contents of a column with a special SQL NULL value. To replace every column that contains an empty string with NULL, use the null("") option, for example

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")
    null(""));
};

To replace only a specific column (for example pid) if it is empty, assign a default value to the column, and use this default value in the null() parameter:

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:-@@NULL@@}", "${MSGONLY}")
    indexes("datetime", "host", "program", "pid", "message")
    null("@@NULL@@"));
};

Ensure that the default value you use does not appear in the actual log messages, because other occurrences of this string will be replaced with NULL as well.


password()
Type: string
Default: n/a

Description: Password of the database user.

port()
Type: number (port number)
Default: 1433 TCP for MSSQL, 3306 TCP for MySQL, 1521 for Oracle, and 5432 TCP for PostgreSQL

Description: The port number to connect to.

retries

Type: number (insertion attempts)
Default: 3

Description: The number of insertion attempts. If syslog-ng PE could not insert a message into the database, it will repeat the attempt until the number of attempts reaches retries, then drops the connection to the database. For example, syslog-ng PE will try to insert a message maximum three times by default (once for first insertion and twice if the first insertion was failed).

session-statements()
Type: comma-separated list of SQL statements
Default: empty string

Description: Specifies one or more SQL-like statement which is executed after syslog-ng PE has successfully connected to the database. For example:

session-statements("SET COLLATION_CONNECTION='utf8_general_ci'")

Caution:

The syslog-ng PE application does not validate or limit the contents of customized queries. Consequently, queries performed with a user with write-access can potentially modify or even harm the database. Use customized queries with care, and only for your own responsibility.

table()
Type: string
Default: messages

Description: Name of the database table to use (can include macros). When using macros, note that some databases limit the length of table names.

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

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see the section called “Date-related macros”.

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.

type()
Type: mssql, mysql, oracle, pgsql, or sqlite3
Default: mysql

Description: Specifies the type of the database, that is, the DBI database driver to use. Use the mssql option to send logs to an MSSQL database. For details, see the examples of the databases on the following sections.

username()
Type: string
Default: n/a

Description: Name of the database user.

values()
Type: string list
Default: "${R_YEAR}-${R_MONTH}-${R_DAY}, ${R_HOUR}:${R_MIN}:${R_SEC}", "${FACILITY}", "${LEVEL}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}"

Description: The parts of the message to store in the fields specified in the columns() parameter.

It is possible to give a special value calling: default (without quotation marks).It means that the value will be used that is the default of the column type of this value.

Example 7.40. Value: default

columns("date datetime", "host varchar(32)", "row_id serial")
values("${R_DATE}", "${HOST}", default)

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