syslog-ng.conf(5)
NAME
syslog-ng.conf - syslog-ng configuration file
SYNOPSIS
syslog-ng.conf
DESCRIPTION
This manual page is only an abstract; for the complete documentation of syslog-ng, see The syslog-ng Open Source Edition Administrator Guide[1] or the official syslog-ng website[2]. The syslog-ng OSE application is a flexible and highly scalable system logging application. Typically, syslog-ng is used to manage log messages and implement centralized logging, where the aim is to collect the log messages of several devices on a single, central log server. The different devices - called syslog-ng clients - all run syslog-ng, and collect the log messages from the various applications, files, and other sources. The clients send all important log messages to the remote syslog-ng server, where the server sorts and stores them. The syslog-ng application reads incoming messages and forwards them to the selected destinations. The syslog-ng application can receive messages from files, remote hosts, and other sources. Log messages enter syslog-ng in one of the defined sources, and are sent to one or more destinations. Sources and destinations are independent objects; log paths define what syslog-ng does with a message, connecting the sources to the destinations. A log path consists of one or more sources and one or more destinations; messages arriving from a source are sent to every destination listed in the log path. A log path defined in syslog-ng is called a log statement. Optionally, log paths can include filters. Filters are rules that select only certain messages, for example, selecting only messages sent by a specific application. If a log path includes filters, syslog-ng sends only the messages satisfying the filter rules to the destinations set in the log path.
CONFIGURING SYSLOG-NG
* The main body of the configuration file consists of object
definitions: sources, destinations, logpaths define which log
message are received and where they are sent. All identifiers,
option names and attributes, and any other strings used in the
syslog-ng configuration file are case sensitive. Objects must be
defined before they are referenced in another statement. Object
definitions (also called statements) have the following syntax:
object_type object_id {<options>};
* Type of the object: One of source, destination, log, filter,
parser, rewrite rule, or template.
* Identifier of the object: A unique name identifying the object.
When using a reserved word as an identifier, enclose the
identifier in quotation marks.
Tip
Use identifiers that refer to the type of the object they
identify. For example, prefix source objects with s_,
destinations with d_, and so on.
* Parameters: The parameters of the object, enclosed in braces
{parameters}.
* Semicolon: Object definitions end with a semicolon (;).
For example, the following line defines a source and calls it
s_internal.
source s_internal { internal(); };
The object can be later referenced in other statements using its
ID, for example, the previous source is used as a parameter of the
following log statement:
log { source(s_internal); destination(d_file); };
* The parameters and options within a statement are similar to
function calls of the C programming language: the name of the
option followed by a list of its parameters enclosed within
brackets and terminated with a semicolon.
option(parameter1, parameter2); option2(parameter1, parameter2);
For example, the following source statement has three options; the
first two options (file() and follow_freq()) have a single
parameter, while the third one (flags()) has two parameters:
source s_tail { file("/var/log/apache/access.log"
follow_freq(1) flags(no-parse, validate-utf8)); };
Objects may have required and optional parameters. Required
parameters are positional, meaning that they must be specified in a
defined order. Optional parameters can be specified in any order
using the option(value) format. If a parameter (optional or
required) is not specified, its default value is used. The
parameters and their default values are listed in the reference
section of the particular object.
Example 1. Using required and optional parameters The unix-stream()
source driver has a single required argument: the name of the
socket to listen on. Optional parameters follow the socket name in
any order, so the following source definitions have the same
effect:
source s_demo_stream1 {
unix-stream("/dev/log" max-connections(10) group(log)); };
source s_demo_stream2 {
unix-stream("/dev/log" group(log) max-connections(10)); };
* Some options are global options, or can be set globally, for
example, whether syslog-ng OSE should use DNS resolution to resolve
IP addresses. Global options are detailed in ???.
options { use_dns(no); };
* All identifiers, attributes, and any other strings used in the
syslog-ng configuration file are case sensitive.
* Objects can be used before definition.
* To add comments to the configuration file, start a line with # and
write your comments. These lines are ignored by syslog-ng.
# Comment: This is a stream source
source s_demo_stream {
unix-stream("/dev/log" max-connections(10) group(log)); };
The syntax of log statements is as follows:
log {
source(s1); source(s2); ...
optional_element(filter1|parser1|rewrite1); optional_element(filter2|parser2|rewrite2);...
destination(d1); destination(d2); ...
flags(flag1[, flag2...]);
};
The following log statement sends all messages arriving to the
localhost to a remote server.
source s_localhost { tcp(ip(127.0.0.1) port(1999) ); };
destination d_tcp { tcp("10.1.2.3" port(1999); localport(999)); };
log { source(s_localhost); destination(d_tcp); };
The syslog-ng application has a number of global options governing DNS
usage, the timestamp format used, and other general points. Each option
may have parameters, similarly to driver specifications. To set global
options, add an option statement to the syslog-ng configuration file
using the following syntax:
options { option1(params); option2(params); ... };
The sources, destinations, and filters available in syslog-ng are
listed below. For details, see The syslog-ng Administrator Guide[1].
- .sp
Table 1. Source drivers available in syslog-ng
Name Description
internal() Messages generated
internally in syslog-ng.
file() Opens the specified file
and reads messages.
pipe(), fifo Opens the specified named
pipe and reads messages.
pacct() Reads messages from the
process accounting logs on
Linux.
program() Opens the specified
application and reads
messages from its standard
output.
sun-stream(), Opens the specified
sun-streams() STREAMS device on Solaris
systems and reads incoming
messages.
syslog() Listens for incoming
messages using the new
IETF-standard syslog
protocol.
system() Automatically detects
which platform syslog-ng
OSE is running on, and
collects the native log
messages of that platform.
tcp(), tcp6() Listens on the specified
TCP port for incoming
messages using the
BSD-syslog protocol over
IPv4 and IPv6 networks,
respectively.
udp(), udp6() Listens on the specified
UDP port for incoming
messages using the
BSD-syslog protocol over
IPv4 and IPv6 networks,
respectively.
unix-dgram() Opens the specified unix
socket in SOCK_DGRAM mode
and listens for incoming
messages.
unix-stream() Opens the specified unix
socket in SOCK_STREAM mode
and listens for incoming
messages.
Table 2. Destination drivers available in syslog-ng
Name Description
file() Writes messages to the
specified file.
fifo(), pipe() Writes messages to the
specified named pipe.
program() Forks and launches the
specified program, and
sends messages to its
standard input.
sql() Sends messages into an SQL
database. In addition to
the standard syslog-ng
packages, the sql()
destination requires
database-specific packages
to be installed. Refer to
the section appropriate
for your platform in ???.
syslog() Sends messages to the
specified remote host
using the IETF-syslog
protocol. The IETF
standard supports message
transport using the UDP,
TCP, and TLS networking
protocols.
tcp() and tcp6() Sends messages to the
specified TCP port of a
remote host using the
BSD-syslog protocol over
IPv4 and IPv6,
respectively.
udp() and udp6() Sends messages to the
specified UDP port of a
remote host using the
BSD-syslog protocol over
IPv4 and IPv6,
respectively.
unix-dgram() Sends messages to the
specified unix socket in
SOCK_DGRAM style (BSD).
unix-stream() Sends messages to the
specified unix socket in
SOCK_STREAM style (Linux).
usertty() Sends messages to the
terminal of the specified
user, if the user is
logged in.
Table 3. Filter functions available in syslog-ng OSE
Name Description
facility() Filter messages based on
the sending facility.
filter() Call another filter
function.
host() Filter messages based on
the sending host.
level() or priority() Filter messages based on
their priority.
match() Use a regular expression
to filter messages based
on a specified header or
content field.
message() Use a regular expression
to filter messages based
their content.
netmask() Filter messages based on
the IP address of the
sending host.
program() Filter messages based on
the sending application.
source() Select messages of the
specified syslog-ng OSE
source statement.
tags() Select messages having the
specified tag.
FILES
/usr/ /etc/syslog-ng/syslog-ng.conf
SEE ALSO
syslog-ng(8) The syslog-ng OSE 3.3 Administrator Guide[1] If you experience any problems or need help with syslog-ng, visit visit the syslog-ng wiki[3] or the syslog-ng mailing list[4]. For news and notifications about of syslog-ng, visit the syslog-ng Insider Blog[5].
AUTHOR
This manual page was written by the BalaBit Documentation Team <documentation@balabit.com>.
COPYRIGHT
The authors grant permission to copy, distribute and/or modify this manual page under the terms of the GNU General Public License Version 2 or newer (GPL v2+).
NOTES
1. The syslog-ng Open Source Edition Administrator Guide
http://www.balabit.com/support/documentation/
2. the official syslog-ng website
http://www.balabit.com/network-security/syslog-ng/
3. visit the syslog-ng wiki
http://www.balabit.com/wiki/syslog-ng-faq
4. syslog-ng mailing list
https://lists.balabit.hu/mailman/listinfo/syslog-ng
5. syslog-ng Insider Blog
http://insider.blogs.balabit.com
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