syslog-ng.conf(5)

📦
version 4.12.0 · 13 versions
, in alpine 3.24, arch rolling, fedora 44, nixpkgs unstable

💖 NAME 💖

hiii bestie, welcome to syslog-ng.conf(5) — The syslog-ng.conf manual page 🎀

syslog-ng.conf — the {{ site.product.short_name }} configuration file. that's it, that's the name section, short but iconic 💅

🦋 SYNOPSIS 🦋

syslog-ng.conf

✨ DESCRIPTION ✨

okay so first thing you need to know: this manual page is only an abstract. it's the teaser trailer, not the whole movie.

The syslog-ng OSE application is a flexible and highly scalable system logging application. no cap, it really is 💖 Typically, syslog-ng OSE 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 OSE clients — all run syslog-ng OSE, 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 OSE PE server, where the server sorts and stores them. it's giving main character energy for your whole infra ✨

🌈 BASIC CONCEPTS OF syslog-ng OSE 🌈

The syslog-ng OSE application reads incoming messages and forwards them to the selected destinations. The syslog-ng OSE application can receive messages from files, remote hosts, and other sources. so many sources, so little time 🙈

Log messages enter syslog-ng OSE 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 OSE 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 OSE is called a log statement. literally the glue holding this whole thing together 🫶

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 OSE sends only the messages satisfying the filter rules to the destinations set in the log path. filter it, bestie, only the chosen ones get through 💅

Other optional elements that can appear in log statements are parsers and rewriting rules. Parsers segment messages into different fields to help processing the messages, while rewrite rules modify the messages by adding, replacing, or removing parts of the messages. slay, we're editing messages now ✨

👑 CONFIGURING syslog-ng OSE 👑

  • 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 OSE configuration file are case sensitive. Object definitions (also called statements) have the following syntax:
type-of-the-object identifier-of-the-object {<parameters>};
  • 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 ((\"\")).

All identifiers, attributes, and any other strings used in the syslog-ng OSE configuration file are case sensitive. yes, CASE SENSITIVE, don't come crying to me when Source doesn't work 😭

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. honestly this tip is so underrated, name your stuff properly bestie 🎀
NOTE: Repeating a definition of an object (that is, defining the same object with the same id more than once) is not allowed, unless you use the @define allow-config-dups 1 definition in the configuration file. like, don't define the same thing twice unless you explicitly said it's fine, that's the rule 👑
  • 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 file() driver in the following source statement has three options: the filename (/var/log/apache/access.log), follow-freq(), and flags(). The follow-freq() option also has a parameter, while the flags() option 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. so if you're lazy (no judgement) the defaults got you 🫶

Example: 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("<path-to-socket>"
    max-connections(10) group(log));
};

source s_demo_stream2 {
    unix-stream("<path-to-socket>"
    group(log) max-connections(10));
};

same thing, different order, both ate 💅

  • Some options are global options, or can be set globally, for example, whether syslog-ng OSE should use DNS resolution to resolve IP addresses.
options { use-dns(no); };
  • Objects can be used before definition.
  • Objects can be defined inline as well. This is useful if you use the object only once (for example, a filter).
  • To add comments to the configuration file, start a line with # and write your comments. These lines are ignored by syslog-ng OSE.
# Comment: This is a stream source

source s_demo_stream {
unix-stream("<path-to-socket>" 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 { network(ip(127.0.0.1) port(1999)); };
destination d_tcp { network("10.1.2.3" port(1999) localport(999)); };
log { source(s_localhost); destination(d_tcp); };

The syslog-ng OSE 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 OSE configuration file using the following syntax:

options { option1(params); option2(params); ... };

For example:

To disable domain name resolving, add the following line to the syslog-ng OSE configuration file:

options { use-dns(no); };

The sources, destinations, and filters available in syslog-ng OSE are listed below. 👀

TABLE 1: SOURCE DRIVERS AVAILABLE IN syslog-ng OSE

okay bestie, here's the whole lineup of source drivers — every single one, no skips, no cap. 💅✨

  • file() — opens the file you specified and reads messages from it. literally file-to-message pipeline. 📂💖
  • wildcard-file() — reads messages from multiple files and directories. it's giving "scavenger hunt but make it logs". 🦋🔍
  • internal() — messages generated internally inside syslog-ng OSE. the software's own little diary entries. 📓✨
  • network() — receives messages from remote hosts using the BSD-syslog protocol over IPv4 and IPv6. supports the TCP, UDP, and TLS network protocols. versatile queen, fr fr. 🌐👑
  • nodejs() — receives JSON messages from nodejs applications. node girlies, this one's for you. 🟢💜
  • mbox() — reads e-mail messages from local mbox files, and converts them to multi-line log messages. inbox but make it logs. 📧➡️📜
  • osquery() — runs osquery queries, and converts their results into log messages. query results but they're serving log realness. 🔎✨
  • pacct() — reads messages from the process accounting logs on Linux. Linux process receipts, periodt. 🐧💅
  • pipe() — opens the specified named pipe and reads messages. named pipe says "let me in". 🚰😭
  • program() — opens the specified application and reads messages from its standard output. app's stdout gets its main character moment. 🎬🔥
  • snmptrap() — reads and parses the SNMP traps of the Net-SNMP's snmptrapd application. trap queen behavior. 🪤👑
  • sun-stream(), sun-streams() — opens the specified STREAMS device on Solaris systems and reads incoming messages. Solaris-only, iconic and niche. ☀️🌊
  • syslog() — listens for incoming messages using the new IETF-standard syslog protocol. modern syslog protocol energy. 📡✨
  • system() — automatically detects which platform syslog-ng OSE is running on, and collects the native log messages of that platform. auto-detect slay. 🖥️💖
  • systemd-journal() — collects messages directly from the journal of platforms that use systemd. straight from the journal, no middleman. 📔🫶
  • systemd-syslog() — collects messages from the journal using a socket on platforms that use systemd. socket-based journal access, lowkey iconic. 🔌🌟
  • unix-dgram() — opens the unix socket you specified in SOCK_DGRAM mode and just... listens for incoming messages. datagram vibes, no cap. 💌
  • unix-stream() — same energy but make it SOCK_STREAM mode: opens the unix socket you specified and listens for incoming messages. 🌊
  • stdin() — collects messages straight from the standard input stream. yes bestie, the actual stdin, iconic behaviour honestly. ⌨️✨

aaaand that's a wrap on TABLE 1, bestie — every single source driver, accounted for, no stragglers, no notes left behind. 🎀

lowkey a lot of drivers tho. but the good news is you don't have to memorise them — you just have to remember that source blocks are where messages enter your config, and each driver is a different door they can walk through. 🚪✨

ngl, if you're skimming: don't. the next bit is where it gets good, and we're still not done. like, not even close. 🔥

the page keeps going, so keep scrolling, bestie 💜

🎯 TABLE 2: DESTINATION DRIVERS AVAILABLE IN syslog-ng OSE 💖

okay bestie, so destinations are literally where your logs go to live. this is the glow-up table, the "where do we send all this tea" list. same rules as before: the driver name is on the left, the vibe is on the right, and every single one is here, no skipping. 🫶

  • amqp() — Publishes messages using the AMQP (Advanced Message Queuing Protocol). fancy message queue energy ✨
  • elasticsearch-http — Sends messages to an Elasticsearch server. yes queen, search them logs
  • file() — Writes messages to the specified file. the classic, the blueprint, the moment 💅
  • graphite() — Sends metrics to a Graphite server to store numeric time-series data. numbers but make it a timeline 📈
  • graylog2() — Sends syslog messages to Graylog.
  • hdfs() — Sends messages into a file on a Hadoop Distributed File System (HDFS) node. big data bestie detected 🔥
  • http() — Sends messages over the HTTP protocol. There are two different implementations of this driver: a Java-based http driver, and an http driver without Java. pick ur fighter 🥊
  • kafka() — Publishes log messages to the Apache Kafka message bus, where subscribers can access them. the way the whole bus is subscribed to ur logs 😭
  • loggly() — Sends log messages to the Loggly Logging-as-a-Service provider. logging-as-a-service, they get it 🌈
  • logmatic() — Sends log messages to the Logmatic.io Logging-as-a-Service provider.
  • mongodb() — Sends messages to a MongoDB database. document vibes, extremely on brand 📄
  • network() — Sends messages to a remote host using the BSD-syslog protocol over IPv4 and IPv6. Supports the TCP, UDP, and TLS network protocols. IPv4 AND IPv6?? inclusive king 👑
  • pipe() — Writes messages to the specified named pipe. named pipe supremacy, no cap 🎀
  • program() — forks and launches the program you name, then pipes messages straight into its standard input. feeding a whole other process fr 💖
  • redis() — yeets messages as name-value pairs into a Redis key-value store. key-value girlie behaviour ✨
  • riemann() — ships metrics or events off to a Riemann monitoring system. monitoring bestie 🎀
  • smtp() — sends e-mail messages to whichever recipients you specify. yes it really does email 🦋
  • sql() — drops messages into an SQL database. heads up tho: on top of the standard syslog-ng OSE packages, the sql() destination needs database-specific packages installed too, so don't come for me when it doesn't build 🙈
  • stomp() — sends messages to a STOMP server. periodt 💅
  • syslog() — sends messages to the remote host you pick using the IETF-syslog protocol, and the IETF standard supports message transport over UDP, TCP, and TLS. three protocols, one icon 👑
  • 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, but only if that user is actually logged in. if they're offline it's giving nothing 😭

🌈 TABLE 3: FILTER FUNCTIONS AVAILABLE IN syslog-ng OSE 🌈

okay so this table is genuinely so real of it — the Description column is literally empty for every single one. not me leaving the vibes column blank 💀. anyway, here are all the filter function names, exactly as they appear:

  • facility()
  • filter()
  • host()
  • inlist()
  • level() or priority()
  • match()
  • message()
  • netmask()
  • program()
  • source()
  • tags()

that's the whole roster, bestie. no descriptions, just names and main character energy ✨

🎀 FILES 🎀

these are the paths, copy them exactly, do not freestyle:

/Users/hofi/Develop/Balabit/syslog-ng/build/install/
/Users/hofi/Develop/Balabit/syslog-ng/build/install/etc/syslog-ng.conf
NOTE: if you experience any problems or need help with syslog-ng OSE, check the syslog-ng OSE Administration Guide[1], or go visit the syslog-ng OSE mailing list[2]. and for news and notifications about syslog-ng OSE, the syslog-ng OSE blogs[3] are right there. we got you 🫶

💖 AUTHOR 💖

this manual page was generated from the syslog-ng OSE Administration Guide[1], which was written by several contributors to whom we'd like to extend our sincere thanks. shoutout to every single one of them, fr fr 🙏✨

🦋 NOTES 🦋

  1. syslog-ng OSE Administration Guide ⟨https://syslog-ng.github.io/admin-guide/README⟩
  2. syslog-ng OSE mailing list ⟨https://lists.balabit.hu/mailman/listinfo/syslog-ng⟩
  3. syslog-ng OSE blogs ⟨https://syslog-ng.com/blog/⟩

and that's the whole page, bestie — you made it to the end of all five parts and honestly? iconic behaviour 💅 this was version 4.10.2, dated 18 December 2025, and it's the syslog-ng.conf(5) manual page. slay, go configure something gorgeous 🌟

📦 where this page comes from