The osquery application allows you to ask questions about your machine using an SQL-like language. For example, you can query running processes, logged in users, installed packages and syslog messages as well. You can make queries on demand, and also schedule them to run regularly.
The osquery() source of syslog-ng PE allows you read the results of periodical osquery queries (from the /var/log/osquery/osqueryd.results.log file) and automatically parse the messages (if you want to use syslog-ng PE to send log messages to osquery, read this blogpost). For example, you can:
-
Create filters from the fields of the messages.
-
Limit which fields to store, or create additional fields (combine multiple fields into one filed, and so on).
-
Send the messages to a central location, for example, to Elasticsearch, directly from syslog-ng PE.
The syslog-ng PE application automatically adds the .osquery. prefix to the name of the fields the extracted from the message.
The osquery() source is available in syslog-ng PE version 7.0.4 and later.
Prerequisites
The osquery() driver is actually a reusable configuration snippet configured to read the osquery log file using the file() driver, and process its JSON contents. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of this configuration snippet on GitHub.
Example: Using the osquery() driver with the default settings
The following syslog-ng PE configuration sample uses the default settings of the driver, reading osquery result logs from the /var/log/osquery/osqueryd.results.log file, and writes the log messages generated from the traps into a file.
@version: 7.0
@include "scl.conf"
source s_osquery {
osquery();
};
log {
source(s_osquery);
destination {
file("/var/log/example.log");
};
};
Filter for messages related to loading Linux kernel modules:
@version: 7.0
@include "scl.conf"
source s_osquery {
osquery();
};
log {
source(s_osquery);
filter f_modules {
"${.osquery.name}" eq "pack_incident-response_kernel_modules"
};
destination {
file("/var/log/example.log");
};
};
Example: Using the osquery() driver with custom configuration
The following syslog-ng PE configuration sample reads osquery result logs from the /tmp/osquery_input.log file, and writes the log messages generated from the traps into a file. Using the format-json template, the outgoing message will be a well-formed JSON message.
Input message
{"name":"pack_osquery-monitoring_osquery_info","hostIdentifier":"testhost","calendarTime":"Fri Jul 21 10:04:41 2017 UTC","unixTime":"1500631481","decorations":{"host_uuid":"4C4C4544-004D-3610-8043-C2C04F4D3332","username":"myuser"},"columns":{"build_distro":"xenial","build_platform":"ubuntu","config_hash":"43cd1c6a7d0c283e21e026a53e619b2e582e94ee","config_valid":"1","counter":"4","extensions":"active","instance_id":"d0c3eb0d-f8e0-4bea-868b-18a2c61b438d","pid":"19764","resident_size":"26416000","start_time":"1500629552","system_time":"223","user_time":"476","uuid":"4C4C4544-004D-3610-8043-C2C04F4D3332","version":"2.5.0","watcher":"19762"},"action":"added"}
syslog-ng PE configuration
@version: 7.0
@include "scl.conf"
source s_osquery {
osquery(
file(/tmp/osquery_input.log)
prefix(.osquery.)
);
};
destination d_file {
file("/tmp/output.txt"
template("$(format_json --key .osquery.*)\n")
);
};
log {
source(s_osquery);
destination(d_file);
flags(flow-control);
};
Outgoing message
Outgoing message; message='{"_osquery":{"unixTime":"1500631481","name":"pack_osquery-monitoring_osquery_info","hostIdentifier":"testhost","decorations":{"username":"myuser","host_uuid":"4C4C4544-004D-3610-8043-C2C04F4D3332"},"columns":{"watcher":"19762","version":"2.5.0","uuid":"4C4C4544-004D-3610-8043-C2C04F4D3332","user_time":"476","system_time":"223","start_time":"1500629552","resident_size":"26416000","pid":"19764","instance_id":"d0c3eb0d-f8e0-4bea-868b-18a2c61b438d","extensions":"active","counter":"4","config_valid":"1","config_hash":"43cd1c6a7d0c283e21e026a53e619b2e582e94ee","build_platform":"ubuntu","build_distro":"xenial"},"calendarTime":"Fri Jul 21 10:04:41 2017 UTC","action":"added"}}\x0a'
To configure a destination to send the log messages to Elasticsearch, see elasticsearch2>: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED). For other destinations, see Sending and storing log messages — destinations and destination drivers.
The osquery() driver has the following options.
file()
| Type: |
path |
| Default: |
/var/log/osquery/osqueryd.results.log |
Description: The log file of osquery that stores the results of periodic queries. The syslog-ng PE application reads the messages from this file.
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.)
Default value
.osquery. option.
The pipe driver opens a named pipe with the specified name and listens for messages. It is used as the native message delivery protocol on HP-UX.
The pipe driver has a single required parameter, specifying the filename of the pipe to open. For the list of available optional parameters, see pipe() source options.
Declaration
pipe(filename);
NOTE: As of syslog-ng Open Source Edition 3.0.2, pipes are created automatically. In earlier versions, you had to create the pipe using the mkfifo(1) command.
Pipe is very similar to the file() driver, but there are a few differences, for example, pipe() opens its argument in read-write mode, therefore it is not recommended to be used on special files like /proc/kmsg.
|
|
Caution:
-
It is not recommended to use pipe() on anything else than real pipes.
-
By default, syslog-ng PE uses the flags(no-hostname) option for pipes, meaning that syslog-ng PE assumes that the log messages received from the pipe do not contain the hostname field. If your messages do contain the hostname field, use flags(expect-hostname). For details, see flags(). |
Example: Using the pipe() driver
source s_pipe {
pipe("/dev/pipe"
pad-size(2048)
);
};
The pipe driver has the following options:
flags()
| Type: |
assume-utf8, empty-lines, expect-hostname, guess-timezone, kernel, no-hostname, no-multi-line, no-parse, sanitize-utf8, store-legacy-msghdr, store-raw-message, syslog-protocol, validate-utf8 |
| Default: |
empty set |
Description: Specifies the log parsing options of the source.
-
assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.
-
empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, syslog-ng PE removes empty lines automatically.
-
expect-hostname: If the expect-hostname flag is enabled, syslog-ng PE will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.
-
kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.
-
no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way syslog-ng PE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:
source s_dell {
network(
port(2000)
flags(no-hostname)
);
};
-
no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.
-
no-parse: By default, syslog-ng PE parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The syslog-ng PE application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.
If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, syslog-ng PE generates a new syslog header (timestamp, host, and so on) automatically. Note that since flags(no-parse) disables message parsing, it interferes with other flags, for example, disables flags(no-multi-line).
-
dont-store-legacy-msghdr: By default, syslog-ng stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (syslog-ng automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.
-
sanitize-utf8: When using the sanitize-utf8 flag, syslog-ng PE converts non-UTF-8 input to an escaped form, which is valid UTF-8.
-
store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another syslog-ng node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 7.0.9 and later.
-
syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.
-
validate-utf8: The validate-utf8 flag enables encoding-verification for messages formatted according to the new IETF syslog standard (for details, see IETF-syslog messages). If theBOMcharacter is missing, but the message is otherwise UTF-8 compliant, syslog-ng automatically adds the BOM character to the message.
follow-freq()
Description: Indicates that the source should be checked periodically. This is useful for files which always indicate readability, even though no new lines were appended. If this value is higher than zero, syslog-ng will not attempt to use poll() on the file, but checks whether the file changed every time the follow-freq() interval (in seconds) has elapsed. Floating-point numbers (for example, 1.5) can be used as well.
keep-timestamp()
| Type: |
yes or no |
| Default: |
yes |
Description: Specifies whether syslog-ng should accept the timestamp received from the sending application or client. If disabled, the time of reception will be used instead. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.
|
|
Caution:
To use the S_ macros, the keep-timestamp() option must be enabled (this is the default behavior of syslog-ng PE). |
log-fetch-limit()
Description: The maximum number of messages fetched from a source during a single poll loop. The destination queues might fill up before flow-control could stop reading if log-fetch-limit() is too high.
log-msg-size()
| Type: |
number (bytes) |
| Default: |
Use the global log-msg-size() option, which defaults to 65536 (64 KiB). |
Description: Maximum length of a message in bytes. This length includes the entire message (the data structure and individual fields). The maximum value that you can set is 268435456 bytes (256 MiB).
For messages using the IETF-syslog message format (RFC5424), the maximal size of the value of an SDATA field is 64 KiB.
NOTE: In most cases, you do not need to set log-msg-size() higher than 10 MiB.
For details on how encoding affects the size of the message, see Message size and encoding.
You can use human-readable units when setting configuration options. For details, see Notes about the configuration syntax.
Uses the value of the global option if not specified.
log-prefix() (DEPRECATED)
Description: A string added to the beginning of every log message. It can be used to add an arbitrary string to any log source, though it is most commonly used for adding kernel: to the kernel messages on Linux. NOTE: This option is deprecated. Use program-override() instead.
multi-line-garbage()
| Type: |
regular expression |
| Default: |
empty string |
Description: Use the multi-line-garbage() option when processing multi-line messages that contain unneeded parts between the messages. Specify a string or regular expression that matches the beginning of the unneeded message parts. If the multi-line-garbage() option is set, syslog-ng PE ignores the lines between the line matching the multi-line-garbage() and the next line matching multi-line-prefix(). See also the multi-line-prefix() option.
When receiving multi-line messages from a source when the multi-line-garbage() option is set, but no matching line is received between two lines that match multi-line-prefix(), syslog-ng PE will continue to process the incoming lines as a single message until a line matching multi-line-garbage() is received.
To use the multi-line-garbage() option, set the multi-line-mode() option to prefix-garbage.
|
|
Caution:
If the multi-line-garbage() option is set, syslog-ng PE discards lines between the line matching the multi-line-garbage() and the next line matching multi-line-prefix(). |
multi-line-mode()
| Type: |
indented|regexp |
| Default: |
empty string |
Description: Use the multi-line-mode() option when processing multi-line messages. The syslog-ng PE application provides the following methods to process multi-line messages: multi-line-mode(indented), and multi-line-mode(prefix-garbage).
-
The indented mode can process messages where each line that belongs to the previous line is indented by whitespace, and the message continues until the first non-indented line. For example, the Linux kernel (starting with version 3.5) uses this format for /dev/log, as well as several applications, like Apache Tomcat.
Example: Processing indented multi-line messages
source s_tomcat {
file("/var/log/tomcat/xxx.log"
multi-line-mode(indented)
);
};
-
The prefix-garbage mode uses a string or regular expression (set in multi-line-prefix()) that matches the beginning of the log messages, ignores newline characters from the source until a line matches the regular expression again, and treats the lines between the matching lines as a single message. For details on using multi-line-mode(prefix-garbage), see the multi-line-prefix() and multi-line-garbage() options.
-
The prefix-suffix mode uses a string or regular expression (set in multi-line-prefix()) that matches the beginning of the log messages, ignores newline characters from the source until a line matches the regular expression set in multi-line-suffix(), and treats the lines between multi-line-prefix() and multi-line-suffix() as a single message. Any other lines between the end of the message and the beginning of a new message (that is, a line that matches the multi-line-prefix() expression) are discarded. For details on using multi-line-mode(prefix-suffix), see the multi-line-prefix() and multi-line-suffix() options.
The prefix-suffix mode is similar to the prefix-garbage mode, but it appends the garbage part to the message instead of discarding it.
TIP:
-
To make multi-line messages more readable when written to a file, use a template in the destination and instead of the ${MESSAGE} macro, use the following: $(indent-multi-line ${MESSAGE}). This expression inserts a tab after every newline character (except when a tab is already present), indenting every line of the message after the first. For example:
destination d_file {
file ("/var/log/messages"
template("${ISODATE} ${HOST} $(indent-multi-line ${MESSAGE})\n")
);
};
For details on using templates, see Templates and macros.
-
To actually convert the lines of multi-line messages to single line (by replacing the newline characters with whitespaces), use the flags(no-multi-line) option in the source.
multi-line-prefix()
| Type: |
regular expression starting with the ^ character |
| Default: |
empty string |
Description: Use the multi-line-prefix() option to process multi-line messages, that is, log messages that contain newline characters (for example, Tomcat logs). Specify a string or regular expression that matches the beginning of the log messages (always start with the ^ character). Use as simple regular expressions as possible, because complex regular expressions can severely reduce the rate of processing multi-line messages. If the multi-line-prefix() option is set, syslog-ng PE ignores newline characters from the source until a line matches the regular expression again, and treats the lines between the matching lines as a single message. See also the multi-line-garbage() option.
TIP:
-
To make multi-line messages more readable when written to a file, use a template in the destination and instead of the ${MESSAGE} macro, use the following: $(indent-multi-line ${MESSAGE}). This expression inserts a tab after every newline character (except when a tab is already present), indenting every line of the message after the first. For example:
destination d_file {
file ("/var/log/messages"
template("${ISODATE} ${HOST} $(indent-multi-line ${MESSAGE})\n")
);
};
For details on using templates, see Templates and macros.
-
To actually convert the lines of multi-line messages to single line (by replacing the newline characters with whitespaces), use the flags(no-multi-line) option in the source.
Example: Processing Tomcat logs
The log messages of the Apache Tomcat server are a typical example for multi-line log messages. The messages start with the date and time of the query in the YYYY.MM.DD HH:MM:SS format, as you can see in the following example.
2010.06.09. 12:07:39 org.apache.catalina.startup.Catalina start
SEVERE: Catalina.start:
LifecycleException: service.getName(): "Catalina"; Protocol handler start failed: java.net.BindException: Address already in use null:8080
at org.apache.catalina.connector.Connector.start(Connector.java:1138)
at org.apache.catalina.core.StandardService.start(StandardService.java:531)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
at org.apache.catalina.startup.Catalina.start(Catalina.java:583)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:288)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.commons.daemon.support.DaemonLoader.start(DaemonLoader.java:177)
2010.06.09. 12:07:39 org.apache.catalina.startup.Catalina start
INFO: Server startup in 1206 ms
2010.06.09. 12:45:08 org.apache.coyote.http11.Http11Protocol pause
INFO: Pausing Coyote HTTP/1.1 on http-8080
2010.06.09. 12:45:09 org.apache.catalina.core.StandardService stop
INFO: Stopping service Catalina
To process these messages, specify a regular expression matching the timestamp of the messages in the multi-line-prefix() option. Such an expression is the following:
source s_file{file("/var/log/tomcat6/catalina.2010-06-09.log" follow-freq(0) multi-line-prefix("[0-9]{4}\.[0-9]{2}\.[0-9]{2}\.") flags(no-parse));};
};
Note that flags(no-parse) is needed to prevent syslog-ng PE trying to interpret the date in the message.
multi-line-suffix()
| Type: |
regular expression |
| Default: |
empty string |
Description: Use the multi-line-suffix() option when processing multi-line messages. Specify a string or regular expression that matches the end of the multi-line message.
To use the multi-line-suffix() option, set the multi-line-mode() option to prefix-suffix. See also the multi-line-prefix() option.
optional()
Description: Instruct syslog-ng to ignore the error if a specific source cannot be initialized. No other attempts to initialize the source will be made until the configuration is reloaded. This option currently applies to the pipe(), unix-dgram, and unix-stream drivers.
pad-size()
Description: Specifies input padding. Some operating systems (such as HP-UX) pad all messages to block boundary. This option can be used to specify the block size. The syslog-ng PE application will pad reads from the associated device to the number of bytes set in pad-size(). Mostly used on HP-UX where /dev/log is a named pipe and every write is padded to 2048 bytes. If pad-size() was given and the incoming message does not fit into pad-size(), syslog-ng will not read anymore from this pipe and displays the following error message:
Padding was set, and couldn't read enough bytes
program-override()
Description: Replaces the ${PROGRAM} part of the message with the parameter string. For example, to mark every message coming from the kernel, include the program-override("kernel") option in the source containing /proc/kmsg.
tags()
Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in syslog-ng 3.1 and later.
time-zone()
| Type: |
name of the timezone, or the timezone offset |
| Default: |
|
Description: The default timezone for messages read from the source. Applies only if no timezone is specified within the message itself.
The timezone can be specified as using the name of the (for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.
