The syslog-ng application can match the contents of the log messages to a database of predefined message patterns (also called patterndb). By comparing the messages to the known patterns, syslog-ng is able to identify the exact type of the messages, tag 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 functionality of the pattern database is similar to that of the logcheck project, but the syslog-ng approach is faster, scales better, and is much easier to maintain compared to the regular expressions of logcheck.

The pdbtool application is a utility that can be used to:

• test message patterns;

• convert an older pattern database to the latest database format;

• merge pattern databases into a single file;

• dump the RADIX tree built from the pattern database (or a part of it) to explore how the pattern matching works.

--pdb or -p

Name of the pattern database file to use.

--program or -P

Displays the RADIX tree built from the patterns belonging to the $PROGRAM application.

--program-tree or -T

Display the $PROGRAM tree.

Example and sample output:

pdbtool dump -p patterndb.xml  -P 'sshd'

'p'
   'assword for'
     @QSTRING:@
       'from'
        @QSTRING:@
          'port '
            @NUMBER:@ rule_id='fc49054e-75fd-11dd-9bba-001e6806451b'
              ' ssh' rule_id='fc55cf86-75fd-11dd-9bba-001e6806451b'
                 '2' rule_id='fc4b7982-75fd-11dd-9bba-001e6806451b'
    'ublickey for'
      @QSTRING:@
        'from'
         @QSTRING:@
           'port '
             @NUMBER:@ rule_id='fc4d377c-75fd-11dd-9bba-001e6806451b'
               ' ssh' rule_id='fc5441ac-75fd-11dd-9bba-001e6806451b'
                  '2' rule_id='fc44a9fe-75fd-11dd-9bba-001e6806451b'
              

• the class assigned to the message (that is, system, violation, and so on),

• the ID of the rule that matched the message, and

• the values of the parsers (if there were parsers in the matching pattern).

The match command has the following options:

--color-out or -c

Color the terminal output to highlight the part of the message that was successfully parsed.

--debug-csv or -C

Print the debugging information returned by the --debug-pattern option as comma-separated values.

--debug-pattern or -D

Print debugging information about the pattern matching. See also the --debug-csv option.

--file=<filename-with-path> or -f

Process the messages of the specified log file with the pattern database. This option allows to classify messages offline, and to apply the pattern database to already existing logfiles. To read the messages from the standard input (stdin), specify a hyphen (-) character instead of a filename.

--filter=<filter-expression> or -F

Print only messages matching the specified syslog-ng filter expression.

--message or -M

The text of the log message to match (only the $MESSAGE part without the syslog headers).

--pdb or -p

Name of the pattern database file to use.

--program or -P

Name of the program to use, as contained in the $PROGRAM part of the syslog message.

--template=<template-expression> or -T

A syslog-ng template expression that is used to format the output messages.

Example: The following command checks if the patterndb.xml file recognizes the Accepted publickey for myuser from 127.0.0.1 port 59357 ssh2 message:

pdbtool match -p patterndb.xml -P sshd -M "Accepted publickey for myuser from 127.0.0.1 port 59357 ssh2"

The following example applies the sshd.pdb pattern database file to the log messages stored in the /var/log/messages file, and displays only the messages that received a useracct tag.

pdbtool match -p sshd.pdb \
  -file /var/log/messages \
  -filter 'tags("usracct");' 

--directory or -D

The directory that contains the pattern database XML files to be merged.

--glob or -G

Specify filenames to be merged using a glob pattern, for example, using wildcards. For details on glob patterns, see man glob. This pattern is applied only to the filenames, and not on directory names.

--pdb or -p

Name of the output pattern database file.

--recursive or -r

Merge files from subdirectories as well.

Example:

pdbtool merge --recursive --directory /home/me/mypatterns/  --pdb /var/lib/syslog-ng/patterndb.xml

Currently it is not possible to convert a file without merging, so if you only want to convert an older pattern database file to the latest format, you have to copy it into an empty directory.

--file=<path> or -f

The logfile containing the log messages to create patterns from. To receive the log messages from the standard input (stdin), use -.

--iterate-outliers or -o

Recursively iterate on the log lines to cover as many log messages with patterns as possible.

--named-parsers or -n

The number of example log messages to include in the pattern database for every pattern. Default value: 1

--samples=<number-of-samples>

Include a generated name in the parsers, for example, .dict.string1, .dict.string2, and so on.

--support=<number> or -S

A pattern is added to the output pattern database if at least the specified percentage of log messages from the input logfile match the pattern. For example, if the input logfile contains 1000 log messages and the --support=3.0 option is used, a pattern is created only if the pattern matches at least 3 percent of the log messages (that is, 30 log messages). If patternize does not create enough patterns, try to decrease the support value.

Default value: 4.0

Example:

pdbtool patternize --support=2.5 --file=/var/log/messages

--validate

Validate a pattern database XML file.

Example:

pdbtool test --validate /home/me/mypatterndb.pdb