syslog-ng Premium Edition 7.0.31 - Administration Guide

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 PE 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 PE 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

Note that not every Cisco log message conforms to this format. If you find a message that the cisco-parser() cannot properly parse, send it to documentation@balabit.com so we can improve the parser.

The syslog-ng PE 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: 7.0
@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 PE. 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.")); 
};

Linux audit parser

The Linux audit parser can parse the log messages of the Linux audit subsystem (auditd). The syslog-ng PE application can separate these log messages to name-value pairs. For details on using value-pairs in syslog-ng PE see Structuring macros, metadata, and other value-pairs. The linux-audit-parser() is available in version 7.0.13 and later.

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 PE application automatically decodes these fields (for example, the c000003e value becomes x86_64).

The syslog-ng PE 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 PE 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

Python parser

The Python log parser (available in syslog-ng PE version 7.0.2 and later) allows you to write your own parser in Python. Practically, that way you can process the log message (or parts of the log message) any way you need.

Only the default Python modules are available (that is, you cannot import external Python modules, and One Identity does not support using external Python modules).
The syslog-ng PE application uses its own Python interpreter (shipped with the default syslog-ng PE installation) instead of the system's Python interpreter.
The syslog-ng PE application is shipped with Python version 3.8.
The Python block must be a top-level block in the syslog-ng PE configuration file.
If you store the Python code in a separate Python file and only include it in the syslog-ng PE configuration file, make sure that the PYTHON_PATH environment variable includes the path to the Python file, and export the PYTHON_PATH environment variable. For example, if you start syslog-ng PE manually from a terminal and you store your Python files in the /opt/syslog-ng/etc directory, use the following command: export PYTHONPATH=/opt/syslog-ng/etc

In production, when syslog-ng PE starts on boot, you must configure your startup script to include the Python path. The exact method depends on your operating system. For recent Red Hat Enterprise Linux, Fedora, and CentOS distributions that use systemd, the systemctl command sources the /etc/sysconfig/syslog-ng file before starting syslog-ng PE. (On openSUSE and SLES, /etc/sysconfig/syslog file.) Append the following line to the end of this file: PYTHONPATH="<path-to-your-python-file>", for example, PYTHONPATH="/opt/syslog-ng/etc"

The Python object is initiated every time when syslog-ng PE is started or reloaded.

Caution:

If you reload syslog-ng PE, existing Python objects are destroyed, therefore the context and state information of Python blocks is lost. Log rotation and updating the configuration of syslog-ng PE typically involves a reload.

The Python block can contain multiple Python functions.
Using Python code in syslog-ng PE can significantly decrease the performance of syslog-ng PE, especially if the Python code is slow. In general, the features of syslog-ng PE are implemented in C, and are faster than implementations of the same or similar features in Python.
Validate and lint the Python code before using it. The syslog-ng PE application does not do any of this.
Python error messages are available in the internal() source of syslog-ng PE.
You can access the name-value pairs of syslog-ng PE directly through a message object or a dictionary.
To help debugging and troubleshooting your Python code, you can send log messages to the internal() source of syslog-ng PE. For details, see Logging from your Python code.

Support disclaimer

Caution:

This is a Preview Feature, which provides an insight to planned enhancements to functionality in the product. Consider this Preview Feature a work in progress, as it may not represent the final design and functionality.

This feature has completed QA release testing, but its full impact on production systems has not been determined yet, and potential future changes in functionality and the user interface may result in compatibility issues in your current settings.

One Identity recommends the following:

Consider the potential risks when using this functionality in a production environment.
Consider the Support Policy on Product Preview Features before using this functionality in a production environment.
Closely and regularly keep track of official One Identity announcements about potential changes in functionality and the user interface. If these potential changes affect your configuration, check the changes you have to make in your configuration, otherwise your syslog-ng PE application may not start after upgrade.
Always perform tests prior to upgrades in order to avoid the risks mentioned.

However, you are welcome to try this feature and if you have any feedback, Contact One Identity.

Support Policy on Product Preview Features

The One Identity Support Team will:

Accept and review each service request opened regarding a Preview Feature.
Consider all service requests relating to a Preview Features as severity level 3.
Provide best effort support to resolve any issues relating to a Preview Feature.
Work with customers to log any product defects or enhancements relating to Preview Features.
Not accept requests for escalations regarding Preview Features.
Not provide after-hours support for Preview Features.

Using Python in syslog-ng PE is recommended only if you are familiar with both Python and syslog-ng PE. One Identity is not responsible for the quality, resource requirements, or any bugs in the Python code, nor any syslog-ng PE crashes, message losses, or any other damage caused by the improper use of this feature, unless explicitly stated in a contract with One Identity.

Declaration

Python parsers consist of two parts. The first is a syslog-ng PE parser object that you use in your syslog-ng PE configuration, for example, in the log path. This parser references a Python class, which is the second part of the Python parsers. The Python class processes the log messages it receives, and can do virtually anything that you can code in Python.

parser <name_of_the_python_parser>{
  python(
    class("<name_of_the_python_class_executed_by_the_parser>")
  );
};

python {
class MyParser(object):
    def init(self, options):
        '''Optional. This method is executed when syslog-ng is started or reloaded.'''
        return True
    def deinit(self):
        '''Optional. This method is executed when syslog-ng is stopped or reloaded.'''
        pass
    def parse(self, msg):
        '''Required. This method receives and processes the log message.'''
        return True
};

Methods of the python() parser

The init (self, options) method (optional)

The syslog-ng PE application initializes Python objects only when it is started or reloaded. That means it keeps the state of internal variables while syslog-ng PE is running. The init method is executed as part of the initialization. You can perform any initialization steps that are necessary for your parser to work. For example, if you want to perform a lookup from a file or a database, you can open the file or connect to the database here, or you can initialize a counter that you will increase in the parse() method.

The return value of the init() method must be True. If it returns False, or raises an exception, syslog-ng PE will not start.

options: This optional argument contains the contents of the options() parameter of the parser object as a Python dict.

parser my_python_parser{
  python(
    class("MyParser")
    options("regex", "seq: (?P<seq>\\d+), thread: (?P<thread>\\d+), runid: (?P<runid>\\d+), stamp: (?P<stamp>[^ ]+) (?P<padding>.*$)")
  );
};
class MyParser(object):
    def init(self, options):
        pattern = options["regex"]
        self.regex = re.compile(pattern)
        self.counter = 0
        return True

The parse(self, log_message) method

The parse() method processes the log messages it receives, and can do virtually anything that you can code in Python. This method is required, otherwise syslog-ng PE will not start.

The return value of the parse() method must be True. If it returns False, or raises an exception, syslog-ng PE will drop the message.

To reference a name-value pair or a macro in the Python code, use the following format. For example, if the first argument in the definition of the function is called log-message, the value of the HOST macro is log-message['HOST'], and so on. (The log-message contains the entire log message (not just the text body) in a structure similar to a Python dict, but it is actually an object.)
You can define new name-value pairs in the Python function. For example, if the first argument in the definition of the function is called log-message, you can create a new name-value pair like this: log_message["new-macro-name"]="value". This is useful when you parse a part of the message from Python, or lookup a value based on data extracted from the log message.

Note that the names of the name-value pairs are case-sensitive. If you create a new name-value pair called new-macro-name in Python, and want to reference it in another part of the syslog-ng PE configuration file (for example, in a template), use the ${new-macro-name} macro.
You cannot override hard macros (see Hard versus soft macros).
To list all available keys (names of name-value pairs), use the log_message.keys() function.

The deinit(self) method (optional)

This method is executed when syslog-ng PE is stopped or reloaded.

Caution:

Example: Parse loggen logs

The following sample code parses the messages of the loggen tool (for details, see The loggen manual page). The following is a sample loggen message:

<38>2017-04-05T12:16:46 localhost prg00000[1234]: seq: 0000000000, thread: 0000, runid: 1491387406, stamp: 2017-04-05T12:16:46 PADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADDPADD

The syslog-ng PE parser object references the LoggenParser class and passes a set of regular expressions to parse the loggen messages. The init() method of the LoggenParser class compiles these expressions into a pattern. The parse method uses these patterns to extract the fields of the message into name-value pairs. The destination template of the syslog-ng PE log statement uses the extracted fields to format the output message.

@version: 7.0
@include "scl.conf"
parser my_python_parser{
  python(
    class("LoggenParser")
    options("regex", "seq: (?P<seq>\\d+), thread: (?P<thread>\\d+), runid: (?P<runid>\\d+), stamp: (?P<stamp>[^ ]+) (?P<padding>.*$)")
  );
};
log {
  source { tcp(port(5555)); };
  parser(my_python_parser);
  destination {  file("/tmp/regexparser.log.txt" template("seq: $seq thread: $thread runid: $runid stamp: $stamp my_counter: $MY_COUNTER"));};
};
python {
import re
class LoggenParser(object):
    def init(self, options):
        pattern = options["regex"]
        self.regex = re.compile(pattern)
        self.counter = 0
        return True
    def deinit(self):
        pass
    def parse(self, log_message):
        match = self.regex.match(log_message['MESSAGE'])
        if match:
            for key, value in match.groupdict().items():
                log_message[key] = value
            log_message['MY_COUNTER'] = self.counter
            self.counter += 1
            return True
        return False
};

Example: Parse Windows eventlogs in Python - performance

The following example uses regular expressions to process Windows log messages received in XML format from the syslog-ng Agent for Windows application. The parser extracts different fields from messages received from the Security and the Application eventlog containers. Using the following configuration file, syslog-ng PE could process about 25000 real-life Windows log messages per second.

@version: 7.0
options {
    keep_hostname(yes);
    keep_timestamp(no);
    stats_level(2);
    use_dns(no);
};
source s_network_aa5fdf25c39d4017a8e504cdb641b477 {
    network(flags(no-parse)
        ip(0.0.0.0)
        log_fetch_limit(1000)
        log_iw_size(100000)
        max_connections(100)
        port(514));
};
parser p_python_parser_79c31da44bb64de6b5de84be4ae15a15 {
    python(options("regex_for_security", ".* Security ID:  (?P<security_id>\\S+)   Account Name:  (?P<account_name>\\S+)   Account Domain:  (?P<account_domain>\\S+)   Logon ID:  (?P<logon_id>\\S+).*Process Name: (?P<process_name>\\S+).*EventID (?P<event_id>\\d+)", "regex_others", "(.*)EventID (?P<event_id>\\d+)")
class("EventlogParser"));
};
destination d_file_78363e1dd90c4ebcbb0ee1eff5a2e310 {
    file("/var/testdb_working_dir/fcd713a2-d48e-4025-9192-ec4a9852cafa.$HOST"
        flush_lines(1000)
        log_fifo_size(200000));
};
log {
    source(s_network_aa5fdf25c39d4017a8e504cdb641b477);
    parser(p_python_parser_79c31da44bb64de6b5de84be4ae15a15);
    destination(d_file_78363e1dd90c4ebcbb0ee1eff5a2e310);

    flags(flow-control);
};

python {
import re
class EventlogParser(object):
    def init(self, options):
        self.regex_security = re.compile(options["regex_for_security"])
        self.regex_others = re.compile(options["regex_others"])
        return True
    def deinit(self):
        pass
    def parse(self, log_message):
        security_match = self.regex_security.match(log_message['MESSAGE'])
        if security_match:
            for key, value in security_match.groupdict().items():
                log_message[key] = value
        else:
            others_match = self.regex_others.match(log_message['MESSAGE'])
            if others_match:
                for key, value in others_match.groupdict().items():
                    log_message[key] = value
        return True
};

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syslog-ng Premium Edition 7.0.31 - Administration Guide

Cisco Parser

Declaration

prefix()

Linux audit parser

Declaration

Example: Using the linux-audit-parser() parser

Options of linux-audit-parser() parsers

prefix()

template()

Python parser

Support disclaimer

Declaration

Methods of the python() parser

The init (self, options) method (optional)

The parse(self, log_message) method

The deinit(self) method (optional)

Example: Parse loggen logs

Example: Parse Windows eventlogs in Python - performance