syslog-ng Open Source Edition 3.25 - Administration Guide

smtp() destination options

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

body()

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

body("syslog-ng OSE received the following alert from $HOST:\n$MSG")

bcc()

Description: The BCC recipient of the email (contents of the BCC field). You can specify the email address, or the name and the email address. Set the bcc() option multiple times to send the email 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()

Description: The CC recipient of the email (contents of the CC field). You can specify the email address, or the name and the email address. Set the cc() option multiple times to send the email 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:

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

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")
        )
    );
};

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")
        )
    );
};

batch-lines()

Description: Specifies how many lines are flushed to a destination in one batch. The syslog-ng OSE application waits for this number of lines to accumulate and sends them off in a single batch. Increasing this number increases throughput as more messages are sent in a single batch, but also increases message latency.

For example, if you set batch-lines() to 100, syslog-ng OSE waits for 100 messages.

If the batch-timeout() option is disabled, the syslog-ng OSE application flushes the messages if it has sent batch-lines() number of messages, or the queue became empty. If you stop or reload syslog-ng OSE or in case of network sources, the connection with the client is closed, syslog-ng OSE automatically sends the unsent messages to the destination.

Note that if the batch-timeout() option is enabled and the queue becomes empty, syslog-ng OSE flushes the messages only if batch-timeout() expires, or the batch reaches the limit set in batch-lines().

For optimal performance, make sure that the syslog-ng OSE source that feeds messages to this destination is configured properly: the value of the log-iw-size() option of the source must be higher than the batch-lines()*workers() of the destination. Otherwise, the size of the batches cannot reach the batch-lines() limit.

batch-timeout()

Description: Specifies the time syslog-ng OSE waits for lines to accumulate in the output buffer. The syslog-ng OSE application sends batches to the destinations evenly. The timer starts when the first message arrives to the buffer, so if only few messages arrive, syslog-ng OSE sends messages to the destination at most once every batch-timeout() milliseconds.

from()

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

from("admin@example.com")

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()

Description: Adds an extra header to the email 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 email, other occurrences will be ignored.

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

hook-commands()

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

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

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

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

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

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

host()

Description: Hostname or IP address of the SMTP server.

log-fifo-size()

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

port()

Description: The port number of the SMTP server.

reply-to()

Description: Replies of the recipient will be sent to this address (contents of the REPLY-TO field). You can specify the email address, or the name and the email address. Set the reply-to() option multiple times to send the email 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()

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

subject()

Description: The SUBJECT field of the email. 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()

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()

Description: The recipient of the email (contents of the TO field). You can specify the email address, or the name and the email address. Set the to() option multiple times to send the email 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.

snmp: 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 OSE macros.

The snmp() driver is available in syslog-ng OSE version 3.22 and later.

The snmp() driver requires the host(), trap-obj(), and snmp-obj() options to be set, as well as the engine-id() and version() options when using the SNMPv3 protocol. For the list of available optional parameters, see snmp() destination options.

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

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')
        );
};

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}')
        );
};

snmp() destination options

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

The snmp() destination has the following options:

log-fifo-size()

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

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()

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 Date-related macros.

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

Splunk: Sending log messages to Splunk

Although syslog-ng OSE currently does not have any built-in integration with Splunk, the existing message-formatting features and flexibility of syslog-ng OSE allows you to forward your log messages to Splunk. In syslog-ng OSE version 3.8 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 OSE see the following posts on the Splunk blog:

• syslog-ng and HEC: Scalable Aggregated Data Collection in Splunk

• Using Syslog-ng with Splunk

Note that the syslog-ng Premium Edition application has a dedicated Splunk destination. For details, see splunk-hec: Sending messages to Splunk HTTP Event Collector.