syslog-ng Premium Edition 7.0.24 - Administration Guide

smtp: Generating SMTP messages (email) 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 email in general. For example, syslog-ng PE does not verify whether the recipient exists.

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

The subject(), body(), and header() fields may include macros which get expanded in the email. 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.

Declaration

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

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")
    );
};

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")
    );
};

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 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 PE 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 file 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")
        )
    );
};

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")

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()

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.

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 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()

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 the disk-buffer option 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.

splunk-hec: Sending messages to Splunk HTTP Event Collector

Version 7.0.12 of syslog-ng PE can directly post log messages to a Splunk deployment using the HTTP Event Collector (HEC) over the HTTP and Secure HTTP (HTTPS) protocols.

HTTPS connection, as well as password- and certificate-based authentication is supported. The content of the events is sent in JSON format.

d_splunk_hec {
    splunk_hec(
        #mandatory
        index("<splunk-index-to-store-messages>")
        token("<event-collector-tokens>")
        url("http://your-splunk-server:8088/services/collector/event")
    );
};

d_splunk_hec {
    splunk_hec(
        # mandatory
        index("<splunk-index-to-store-messages>")
        token("<event-collector-tokens>")
        url("http://your-splunk-server:8088/services/collector/event")

        # optional
        batch_lines(25)
        workers(4)
        source("syslog-ng")
        sourcetype("${.app.name:-syslog}")
        delimiter("\n")
        time("$S_UNIXTIME.$S_MSEC")
        host("$HOST")
        event("$S_ISODATE $HOST $MSGHDR$MSG\n")
        timeout(10));
    );
};

log {
    source(s_file);
    destination(d_splunk_hec);
    flags(flow-control);
};

Batch mode and load balancing

destination d_splunk-hec {
    splunk-hec(url("http://your-splunk-server:8088/services/collector/event")
        index("<splunk-index-to-store-messages>")
        token("<event-collector-tokens>")
        url("http://your-splunk-server:8088/services/collector/event")
        batch-lines(100)
        batch-bytes(512Kb)
        batch-timeout(10000)
    );
};

destination d_splunk-hec {
    splunk-hec(url("http://your-splunk-server1:8088/services/collector/event" "http://your-splunk-server2:8088/services/collector/event" "http://your-splunk-server3:8088/services/collector/event")
        batch-lines(100)
        batch-bytes(512Kb)
        batch-timeout(20000)
        persist-name("d_splunk-hec-load-balance")
    );
};