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syslog-ng Open Source Edition 3.25 - 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 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 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

Websense parser

The Websense parser can parse the log messages of Websense Content Gateway (Raytheon|Websense, now Forcepoint). These messages do not completely comply with the syslog RFCs, making them difficult to parse. The websense-parser() of syslog-ng OSE solves this problem, and 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 parser can parse messages in the following format:

<PRI><DATE> <TIMEZONE> <IP-ADDRESS> <NAME=VALUE PAIRS>

For example:

<159>Dec 19 10:48:57 EST 192.168.1.1 vendor=Websense product=Security product_version=7.7.0 action=permitted severity=1 category=153 user=- src_host=192.168.2.1 src_port=62189 dst_host=example.com dst_ip=192.168.3.1 dst_port=443 bytes_out=197 bytes_in=76 http_response=200 http_method=CONNECT http_content_type=- http_user_agent=Mozilla/5.0_(Windows;_U;_Windows_NT_6.1;_enUS;_rv:1.9.2.23)_Gecko/20110920_Firefox/3.6.23 http_proxy_status_code=200 reason=- disposition=1034 policy=- role=8 duration=0 url=https://example.com

If you find a message that the websense-parser() cannot properly parse, open a GitHub issue so we can improve the parser.

The syslog-ng OSE application sets the ${PROGRAM} field to Websense.

By default, the websense-specific fields are extracted into name-value pairs prefixed with .websense. For example, the product_version in the previous message becomes ${.websense.product_version}. You can change the prefix using the prefix option of the parser.

Declaration:
@version: 3.25
@include "scl.conf"
log {
    source { network(flags(no-parse)); };
    parser { websense-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 websense-parser() is actually a reusable configuration snippet configured to parse websense 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, websense-parser() uses the websense. prefix. To modify it, use the following format:

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

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Check Point Log Exporter parser

The Check Point Log Exporter parser can parse Check Point log messages. These messages do not completely comply with the syslog RFCs, making them difficult to parse. The checkpoint-parser() of syslog-ng OSE solves this problem, and 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 parser can parse messages in the following formats:

<PRI><VERSION> <YYYY-MM-DD> <HH-MM-SS> <PROGRAM> <PID> <MSGID> - [key1:value1; key2:value2; ... ]

For example:

<134>1 2018-03-21 17:25:25 MDS-72 CheckPoint 13752 - [action:"Update"; flags:"150784"; ifdir:"inbound"; logid:"160571424"; loguid:"{0x5ab27965,0x0,0x5b20a8c0,0x7d5707b6}";]

Splunk format:

time=1557767758|hostname=r80test|product=Firewall|layer_name=Network|layer_uuid=c0264a80-1832-4fce-8a90-d0849dc4ba33|match_id=1|parent_rule=0|rule_action=Accept|rule_uid=4420bdc0-19f3-4a3e-8954-03b742cd3aee|action=Accept|ifdir=inbound|ifname=eth0|logid=0|loguid={0x5cd9a64e,0x0,0x5060a8c0,0xc0000001}|origin=192.168.96.80|originsicname=cn\=cp_mgmt,o\=r80test..ymydp2|sequencenum=1|time=1557767758|version=5|dst=192.168.96.80|inzone=Internal|outzone=Local|proto=6|s_port=63945|service=443|service_id=https|src=192.168.96.27|

If you find a message that the checkpoint-parser() cannot properly parse, open a GitHub issue so we can improve the parser.

By default, the Check Point-specific fields are extracted into name-value pairs prefixed with .checkpoint. For example, the action in the previous message becomes ${.checkpoint.action}. You can change the prefix using the prefix option of the parser.

Declaration:
@version: 3.25
@include "scl.conf"
log {
    source { network(flags(no-parse)); };
    parser { checkpoint-parser(); };
    destination { ... };
};

Note that the parser expects that the entire incorrectly formatted syslog message (starting with its <PRI> value) is in $MSG, which you can achieve by using flags(no-parse) on the input driver.

The checkpoint-parser() is actually a reusable configuration snippet configured to parse Check Point 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, checkpoint-parser() uses the checkpoint. prefix. To modify it, use the following format:

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

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db-parser: Process message content with a pattern database (patterndb)


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Classifying log messages

The syslog-ng application can compare the contents of the received log messages to predefined message patterns. By comparing the messages to the known patterns, syslog-ng is able to identify the exact type of the messages, and sort them into message classes. The message classes can be used to classify the type of the event described in the log message. The message classes can be customized, and for example, can label the messages as user login, application crash, file transfer, and so on events.

To find the pattern that matches a particular message, syslog-ng uses a method called longest prefix match radix tree. This means that syslog-ng creates a tree structure of the available patterns, where the different characters available in the patterns for a given position are the branches of the tree.

To classify a message, syslog-ng selects the first character of the message (the text of message, not the header), and selects the patterns starting with this character, other patterns are ignored for the rest of the process. After that, the second character of the message is compared to the second character of the selected patterns. Again, matching patterns are selected, and the others discarded. This process is repeated until a single pattern completely matches the message, or no match is found. In the latter case, the message is classified as unknown, otherwise the class of the matching pattern is assigned to the message.

To make the message classification more flexible and robust, the patterns can contain pattern parsers: elements that match on a set of characters. For example, the NUMBER parser matches on any integer or hexadecimal number (for example, 1, 123, 894054, 0xFFFF, and so on). Other pattern parsers match on various strings and IP addresses. For the details of available pattern parsers, see Using pattern parsers.

The functionality of the pattern database is similar to that of the logcheck project, but it is much easier to write and maintain the patterns used by syslog-ng, than the regular expressions used by logcheck. Also, it is much easier to understand syslog-ng pattens than regular expressions.

Pattern matching based on regular expressions is computationally very intensive, especially when the number of patterns increases. The solution used by syslog-ng can be performed real-time, and is independent from the number of patterns, so it scales much better. The following patterns describe the same message: Accepted password for bazsi from 10.50.0.247 port 42156 ssh2

A regular expression matching this message from the logcheck project: Accepted (gssapi(-with-mic|-keyex)?|rsa|dsa|password|publickey|keyboard-interactive/pam) for [^[:space:]]+ from [^[:space:]]+ port [0-9]+( (ssh|ssh2))?

A syslog-ng database pattern for this message: Accepted @QSTRING:auth_method: @ for@QSTRING:username: @from @QSTRING:client_addr: @port @NUMBER:port:@ ssh2

For details on using pattern databases to classify log messages, see Using pattern databases.


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