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syslog-ng Open Source Edition 3.33 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng The syslog-ng OSE quick-start guide The syslog-ng OSE configuration file source: Read, receive, and collect log messages
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 linux-audit: Collecting messages from Linux audit logs network: Collecting messages using the RFC3164 protocol (network() driver) nodejs: Receiving JSON messages from nodejs applications mbox: Converting local email messages to log messages osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes pacct: Collecting process accounting logs on Linux program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources 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— OBSOLETE unix-stream, unix-dgram: Collecting messages from UNIX domain sockets stdin: Collecting messages from the standard input stream
destination: Forward, send, and store log messages
amqp: Publishing messages using AMQP collectd: sending metrics to collectd elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API file: Storing messages in plain-text files graphite: Sending metrics to Graphite Sending logs to Graylog hdfs: Storing messages on the Hadoop Distributed File System (HDFS) Posting messages over HTTP http: Posting messages over HTTP without Java kafka: Publishing messages to Apache Kafka (Java implementation) kafka(): Publishing messages to Apache Kafka (C implementation, using the librdkafka client) loggly: Using Loggly logmatic: Using Logmatic.io mongodb: Storing messages in a MongoDB database mqtt() destination: sending messages from a local network to an MQTT broker network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) osquery: Sending log messages to osquery's syslog table pipe: Sending messages to named pipes program: Sending messages to external applications pseudofile() python: writing custom Python destinations redis: Storing name-value pairs in Redis riemann: Monitoring your data with Riemann slack: Sending alerts and notifications to a Slack channel smtp: Generating SMTP messages (email) from logs snmp: Sending SNMP traps Splunk: Sending log messages to Splunk sql: Storing messages in an SQL database stomp: Publishing messages using STOMP Sumo Logic destinations: sumologic-http() and sumologic-syslog() syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng(): Forward logs to another syslog-ng node tcp, tcp6, udp, udp6: Sending messages to a remote log server using the legacy BSD-syslog protocol (tcp(), udp() drivers) Telegram: Sending messages to Telegram unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal: usertty() destination Write your own custom destination in Java or Python Client-side failover
log: Filter and route log messages using log paths, flags, and filters Global options of syslog-ng OSE TLS-encrypted message transfer template and rewrite: Format, modify, and manipulate log messages parser: Parse and segment structured messages db-parser: Process message content with a pattern database (patterndb) Correlating log messages Enriching log messages with external data Statistics of syslog-ng Multithreading and scaling in syslog-ng OSE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd) License Glossary

Linux audit parser

The Linux audit parser can parse the log messages of the Linux Audit subsystem (auditd). The syslog-ng OSE application can separate these log messages to name-value pairs. For details on using value-pairs in syslog-ng OSE see Structuring macros, metadata, and other value-pairs. The following is a sample log message of auditd:

type=SYSCALL msg=audit(1441988805.991:239): arch=c000003e syscall=59 success=yes exit=0 a0=7fe49a6d0e98 a1=7fe49a6d0e40 a2=7fe49a6d0e80 a3=2 items=2 ppid=3652 pid=3660 auid=1000 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=5 comm="dumpe2fs" exe="/sbin/dumpe2fs" key=(null)
type=EXECVE msg=audit(1441988805.991:239): argc=3 a0="dumpe2fs" a1="-h" a2="/dev/sda1"
type=CWD msg=audit(1441988805.991:239):  cwd="/"
type=PATH msg=audit(1441988805.991:239): item=0 name="/sbin/dumpe2fs" inode=137078 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 nametype=NORMAL
type=PATH msg=audit(1441988805.991:239): item=1 name="/lib64/ld-linux-x86-64.so.2" inode=5243184 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 nametype=NORMAL
type=PROCTITLE msg=audit(1441988805.991:239): proctitle=64756D7065326673002D68002F6465762F73646131

Certain fields of the audit log can be encoded in hexadecimal format, for example, the arch field, or the a<number> fields in the previous example. The syslog-ng OSE application automatically decodes these fields (for example, the c000003e value becomes x86_64).

The syslog-ng OSE application extracts every field into name-value pairs. It automatically decodes the following fields:

  • name

  • proctitle

  • path

  • dir

  • comm

  • ocomm

  • data

  • old

  • new

To parse the log messages of the Linux Audit subsystem, define a parser that has the linux-audit-parser() option. By default, the parser will process the ${MESSAGE} part of the log message. To process other parts of a log message, use the template() option. You can also define the parser inline in the log path.

Declaration:
parser parser_name {
    linux-audit-parser(
        prefix()
        template()
    );
};
Example: Using the linux-audit-parser() parser

In the following example, the source is a log file created by auditd. Since the audit log format is not a syslog format, the syslog parser is disabled, so that syslog-ng OSE does not parse the message: flags(no-parse). The parser inserts ".auditd." prefix before all extracted name-value pairs. The destination is a file, that uses the format-json template function. Every name-value pair that begins with a dot (".") character will be written to the file (dot-nv-pairs). The log line connects the source, the destination, and the parser.

source s_auditd {
    file(/var/log/audit/audit.log flags(no-parse));
};

destination d_json {
    file(
        "/tmp/test.json"
        template("$(format-json .auditd.*)\n")
    );
};

parser p_auditd {
    linux-audit-parser (prefix(".auditd."));
};

log {
    source(s_auditd);
    parser(p_auditd);
    destination(d_json);
};

You can also define the parser inline in the log path.

source s_auditd {
    file(/var/log/audit/audit.log);
};

destination d_json {
    file(
        "/tmp/test.json"
        template("$(format-json .auditd.*)\n")
    );
};

log {
    source(s_auditd);
    parser {
        linux-audit-parser (prefix(".auditd."));
    };
    destination(d_json);
};

Options of linux-audit-parser() parsers

The linux-audit-parser() has the following options.

prefix()
Synopsis: prefix()

Description: Insert a prefix before the name part of the parsed name-value pairs to help further processing. For example:

  • To insert the my-parsed-data. prefix, use the prefix(my-parsed-data.) option.

  • To refer to a particular data that has a prefix, use the prefix in the name of the macro, for example, ${my-parsed-data.name}.

  • If you forward the parsed messages using the IETF-syslog protocol, you can insert all the parsed data into the SDATA part of the message using the prefix(.SDATA.my-parsed-data.) option.

Names starting with a dot (for example, .example) are reserved for use by syslog-ng OSE. If you use such a macro name as the name of a parsed value, it will attempt to replace the original value of the macro (note that only soft macros can be overwritten, see Hard versus soft macros for details). To avoid such problems, use a prefix when naming the parsed values, for example, prefix(my-parsed-data.)

By default, linux-audit-parser() uses the .auditd. prefix. To modify it, use the following format:

parser {
    linux-audit-parser(prefix("myprefix."));
};
template()
Synopsis: template("${<macroname>}")

Description: The macro that contains the part of the message that the parser will process. It can also be a macro created by a previous parser of the log path. By default, the parser processes the entire message (${MESSAGE}).

Cisco parser

The Cisco parser can parse the log messages of various Cisco devices. The messages of these devices often do not completely comply with the syslog RFCs, making them difficult to parse. The cisco-parser() of syslog-ng OSE solves this problem, and can separate these log messages to name-value pairs, extracting also the Cisco-specific values, for example, the mnemonic. For details on using value-pairs in syslog-ng OSE see Structuring macros, metadata, and other value-pairs. The parser can parse variations of the following message format:

<pri>(sequence: )?(origin-id: )?(timestamp? timezone?: )?%msg

For example:

<189>29: foo: *Apr 29 13:58:40.411: %SYS-5-CONFIG_I: Configured from console by console
<190>30: foo: *Apr 29 13:58:46.411: %SYS-6-LOGGINGHOST_STARTSTOP: Logging to host 192.168.1.239 stopped - CLI initiated
<190>31: foo: *Apr 29 13:58:46.411: %SYS-6-LOGGINGHOST_STARTSTOP: Logging to host 192.168.1.239 started - CLI initiated
<189>32: 0.0.0.0: *Apr 29 13:59:12.491: %SYS-5-CONFIG_I: Configured from console by console
<189>32: foo: *Apr 29 13:58:46.411: %SYSMGR-STANDBY-3-SHUTDOWN_START: The System Manager has started the shutdown procedure.

Note that not every Cisco log message conforms to this format. If you find a message that the cisco-parser() cannot properly parse, open a GitHub issue so we can improve the parser.

The syslog-ng OSE application normalizes the parsed log messages into the following format:

${MESSAGE}=%FAC-SEV-MNEMONIC: message
${HOST}=origin-id

By default, the Cisco-specific fields are extracted into the following name-value pairs:${.cisco.facility}, ${.cisco.severity}, ${.cisco.mnemonic}. You can change the prefix using the prefix option.

Declaration:
@version: 3.33
@include "scl.conf"
log {
    source { udp(flags(no-parse)); };
    parser { cisco-parser(); };
    destination { ... };
};

Note that you have to disable message parsing in the source using the flags(no-parse) option for the parser to work.

The cisco-parser() is actually a reusable configuration snippet configured to parse Cisco messages. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of this configuration snippet on GitHub.

prefix()
Synopsis: prefix()

Description: Insert a prefix before the name part of the parsed name-value pairs to help further processing. For example:

  • To insert the my-parsed-data. prefix, use the prefix(my-parsed-data.) option.

  • To refer to a particular data that has a prefix, use the prefix in the name of the macro, for example, ${my-parsed-data.name}.

  • If you forward the parsed messages using the IETF-syslog protocol, you can insert all the parsed data into the SDATA part of the message using the prefix(.SDATA.my-parsed-data.) option.

Names starting with a dot (for example, .example) are reserved for use by syslog-ng OSE. If you use such a macro name as the name of a parsed value, it will attempt to replace the original value of the macro (note that only soft macros can be overwritten, see Hard versus soft macros for details). To avoid such problems, use a prefix when naming the parsed values, for example, prefix(my-parsed-data.)

By default, cisco-parser() uses the .cisco. prefix. To modify it, use the following format:

parser {
    cisco-parser(prefix("myprefix."));
};

Parsing enterprise-wide message model (EWMM) messages

The ewmm-parser() can be used to parse messages sent by another syslog-ng host using the enterprise-wide message model (EWMM) format. Available in version 3.16 and later. Note that usually you do not have to use this parser directly, because the default-network-drivers() source automatically parses such messages.

Declaration:
parser parser_name {
    ewmm-parser();
};
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