localfile

This configuration section is used to configure the collection of log data from files, Windows events, and from the output of commands.

Options

location
command
alias
frequency
only-future-events
query
label
log_format

location

This indicates the location of a log or wild-carded group of logs to be read. strftime format strings may be used for log file names.

For instance, a log file named file.log-2017-01-22 could be referenced with file.log-%Y-%m-%d (assuming today is Jan 22nd, 2017).

Wildcards may be used on non-Windows systems, however, the log file must exist at the time ossec-logcollector is started as it will not automatically begin monitoring new log files.

Note that strftime format strings and wildcards cannot be used on the same entry.

Default value	n/a
Allowed values	Any log file

command

This designates a command to be run. All output from this command will be read as one or more log messages depending on whether command or full_command is used.

Default value	n/a
Allowed values	any command line, optionally including arguments

alias

This is used to assign an alias to a command that will replace the command name in the log message.

Default value	n/a
Allowed values	any string

For example <alias>usb-check</alias> would replace:

ossec: output: 'reg QUERY HKLM\SYSTEM\CurrentControlSet\Enum\USBSTOR':

with:

ossec: output: 'usb-check':

frequency

The specifies the minimum amount of time in seconds between command runs. The command will likely not repeat in the exact the number of seconds specified, however, the time between runs will be no less than the number of seconds specified.

This can be used with command or full_command.

Default value	n/a
Allowed values	any positive number of seconds

only-future-events

This is only to be used with the eventchannel log format. By default, when Wazuh starts, it will read all log content from a given Windows Event Channel since the last time Wazuh was stopped.

If this is set to yes Wazuh would then only receive events that occurred after the agent was started.

Default value	n/a
Allowed values	yes or no

query

This is also only to be used with the eventchannel log format. With this option, you can identify an XPATH query following the event schema that will filter the events that Wazuh will process.

Default value	n/a
Allowed values	Any XPATH query following the event schema

For example, the following configuration will only process events with an ID of 7040:

<localfile>
   <location>System</location>
   <log_format>eventchannel</log_format>
   <query>Event/System[EventID=7040]</query>
</localfile>

label

New in version 3.0.0.

This option allows for the addition of custom data in JSON events and is available when log_format is set to json.

Labels can be nested in JSON formatted alerts by separating the "key" terms by a period.

This option can be used as follows to identify the source of each log entry when monitoring several files simultaneously:

<localfile>
  <location>/var/log/myapp/log.json</location>
  <log_format>json</log_format>
  <label key="@source">myapp</label>
  <label key="agent.type">webserver</label>
</localfile>

This is a sample JSON object from the log file:

{
  "event": {
    "type": "write",
    "destination": "sample.txt"
  },
  "agent": {
    "name": "web01"
  }
}

The additional fields configured above would appear in the resulting event as below:

{
  "event": {
    "type": "write",
    "destination": "sample.txt"
  },
  "agent": {
    "name": "web01",
    "type": "webserver"
  },
  "@source": "myapp"
}

Note

If a label key already exists in the log data, the configured field value will not be included. It is recommended that a unique label key be defined by using a symbol prior to the key name as in @source.

log_format

This specifies the format of the log being read.

Note

For most of the text log files that only have one entry per line, syslog may be used.

Default value	syslog
Allowed values	syslog	Used for plain text files in a syslog-like format.
	json	Used for single-line JSON files and allows for customized labels to be added to JSON events. See also the tag label for more information. New in version 3.0.0.
	snort-full	Used for Snort’s full-output format.
	snort-fast	Used for Snort's fast-output format.
	squid	Used for squid logs.
	iis	Used for IIS logs.
	eventlog	Used for the classic Microsoft Windows event log format.
	eventchannel	Used for Microsoft Windows event logs, using the new EventApi. This can be used to monitor standard “Windows” event logs and "Application and Services" logs.
	audit	Used for events from Auditd. This format chains consecutive logs with the same ID into a single event.
	mysql_log	Used for `MySQL` logs, however, this value does not support multi-line logs.
	postgresql_log	Used for `PostgreSQL` logs, however, this value does not support multi-line logs.
	nmapg	Used for monitoring files conforming to the grep-able output from `nmap`.
	apache	Used for Apache's default log format.
	command	Used to read output from the command (as run by root) specified by the command tag. Each line of output is be treated as a separate log.
	full_command	Used to read output from the command (as run by root) specified by the command tag. The entire output will be treated as a single log item.
	djb-multilog	Used to read files in the format produced by the multilog service logger in daemontools.
	multi-line	Used to monitor applications that log multiple lines per event. The number of lines must be consistent in order to use this value. The number of lines in each log entry must be specified following the `multi-line:` value. Each line will be combined with the previous lines until all lines are gathered which means there may be multiple timestamps in the final event. The format for this value is: <log_format>multi-line: NUMBER</log_format>

Warning

The eventchannel log format cannot be used on Windows agents prior to the Vista OS as they do not produce this type of log.

Warning

Agents will ignore command and full_command log sources unless they have logcollector.remote_commands=1 set in their /var/ossec/etc/internal_options.conf or /var/ossec/etc/local_internal_options.conf file. This is a security precaution to prevent the Wazuh Manager from running arbitrary commands on agents in their root security context.

Sample of Multi-line log message in original log file:

Aug 9 14:22:47 hostname log line one
Aug 9 14:22:47 hostname log line two
Aug 9 14:22:47 hostname log line four
Aug 9 14:22:47 hostname log line three
Aug 9 14:22:47 hostname log line five

Sample Log message as analyzed by ossec-analysisd:

Aug 9 14:22:47 hostname log line one Aug 9 14:22:47 hostname log line two Aug 9 14:22:47 hostname log line three Aug 9 14:22:47 hostname log line four Aug 9 14:22:47 hostname log line five

Configuration examples

Linux configuration:

<!-- For monitoring log files -->
<localfile>
  <log_format>syslog</log_format>
  <location>/var/log/syslog</location>
</localfile>

<!-- For monitoring command output -->
<localfile>
  <log_format>command</log_format>
  <command>df -P</command>
  <frequency>360</frequency>
</localfile>

Windows configuration:

<!-- For monitoring Windows eventchannel -->
<localfile>
  <location>Security</location>
  <log_format>eventchannel</log_format>
  <only-future-events>yes</only-future-events>
  <query>Event/System[EventID != 5145 and EventID != 5156]</query>
</localfile>