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SYSLOG\-NG\.CONF

Section: The syslog-ng.conf manual page (5)
Updated: 11/30/2009
Index Return to Main Contents

NAME

syslog-ng.conf - syslog-ng configuration file

SYNOPSIS

syslog-ng.conf

DESCRIPTION

NOTE: This manual page covers both editions of syslog-ng: syslog-ng Open Source Edition and the commercial syslog-ng Premium Edition. Features that are only included in the Premium Edition are marked with an asterisk (*). For details, see the official syslog-ng website: http://www.balabit.com/network-security/syslog-ng/.

This manual page is only an abstract; for the complete documentation of syslog-ng, see The syslog-ng Administrator Guide [1].

The syslog-ng 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 to 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

Global objects (e.g., sources, destinations, log paths, or filters) are defined in the syslog-ng configuration file. Object definitions consist of the following elements:

: *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 (;).

The syntax is summarized as follows:

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].

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.
program()	Opens the specified application and reads messages from its standard output.
sun-stream(), sun-streams()	Opens the specified STREAMS device on Solaris systems and reads incoming messages.
syslog()	Listens for incoming messages using the new IETF-standard syslog protocol.
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.
logstore()*	Writes messages to the specified binary logstore file. *Available only in syslog-ng Premium Edition.
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 in syslog-ng

Name	Synopsis	Description
facility()	facility(facility[,facility])	Match messages having one of the listed facility code. An alternate syntax permits the use an arbitrary facility codes.
facility()	facility(<numeric facility code>)	An alternate syntax for facility permitting the use of an arbitrary facility code. Facility codes 0-23 are predefined and can be referenced by their usual name. Facility codes above 24 are not defined but can be used by this alternate syntax.
filter()	filter(filtername)	Call another filter rule and evaluate its value.
host()	host(regexp)	Match messages by using a regular expression against the hostname field of log messages.
level() or priority()	level(pri[,pri1..pri2[,pri3]])	Match messages based on priority.
match()	match(regexp)	Match a regular expression to the headers and the message itself (i.e., the values returned by the MSGHDR and MSG macros). Note that in syslog-ng version 2.1 and earlier, the match() filter was applied only to the text of the message, excluding the headers. This functionality has been moved to the message() filter. To limit the scope of the match to a specific part of the message (identified with a macro), use the match(regexp value("$MACRO")) syntax.
message()	message(regexp)	Match a regular expression to the text of the log message, excluding the headers (i.e., the value returned by the MSG macros). Note that in syslog-ng version 2.1 and earlier, this functionality was performed by the match() filter.
netmask()	netmask(ip/mask)	Select only messages sent by a host whose IP address belongs to the specified IP subnet. Note that this filter checks the IP address of the last-hop relay (the host that actually sent the message to syslog-ng), not the contents of the HOST field of the message.
program()	program(regexp)	Match messages by using a regular expression against the program name field of log messages.
source()	string	Select messages of a source statement. This filter can be used in embedded log statements if the parent statement contains multiple source groups --- only messages originating from the selected source group are sent to the destination of the embedded log statement.
tags()	tag	Select messages labeled with the specified tag. Every message automatically has the tag of its source in .source.<id_of_the_source_statement> format. This option is available only in syslog-ng 3.1 and later.

FILES

/opt/syslog-ng/etc/syslog-ng/

/opt/syslog-ng/etc/syslog-ng/syslog-ng.conf

AUTHOR

This manual page was written by the BalaBit Documentation Team <documentation@balabit.com>.

COPYRIGHT

Copyright © 2000-2009 BalaBit IT Security Ltd. Published under the Creative Commons Attribution-Noncommercial-No Derivative Works (by-nc-nd) 3.0 license. See http://creativecommons.org/ for details. The latest version is always available at http://www.balabit.com/support/documentation.