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syslog-ng Premium Edition 7.0.24 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng PE The syslog-ng PE quick-start guide The syslog-ng PE configuration file Collecting log messages — sources and source drivers
How sources work default-network-drivers: Receive and parse common syslog messages internal: Collecting internal messages file: Collecting messages from text files google-pubsub: collecting messages from the Google Pub/Sub messaging service wildcard-file: Collecting messages from multiple text files linux-audit: Collecting messages from Linux audit logs mssql, oracle, sql: collecting messages from an SQL database network: Collecting messages using the RFC3164 protocol (network() driver) office365: Fetching logs from Office 365 osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources snmptrap: Read Net-SNMP traps syslog: Collecting messages using the IETF syslog protocol (syslog() driver) system: Collecting the system-specific log messages of a platform systemd-journal: Collecting messages from the systemd-journal system log storage systemd-syslog: Collecting systemd messages using a socket tcp, tcp6, udp, udp6: Collecting messages from remote hosts using the BSD syslog protocol udp-balancer: Receiving UDP messages at very high rate unix-stream, unix-dgram: Collecting messages from UNIX domain sockets windowsevent: Collecting Windows event logs
Sending and storing log messages — destinations and destination drivers
elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Event Collector file: Storing messages in plain-text files google_pubsub: Sending logs to the Google Cloud Pub/Sub messaging service hdfs: Storing messages on the Hadoop Distributed File System (HDFS) http: Posting messages over HTTP kafka: Publishing messages to Apache Kafka logstore: Storing messages in encrypted files mongodb: Storing messages in a MongoDB database network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) pipe: Sending messages to named pipes program: Sending messages to external applications python: writing custom Python destinations sentinel: Sending logs to the Microsoft Azure Sentinel cloud snmp: Sending SNMP traps smtp: Generating SMTP messages (email) from logs splunk-hec: Sending messages to Splunk HTTP Event Collector sql: Storing messages in an SQL database stackdriver: Sending logs to the Google Stackdriver cloud syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng(): Forward logs to another syslog-ng node tcp, tcp6, udp, udp6: Sending messages to a remote log server using the legacy BSD-syslog protocol (tcp(), udp() drivers) unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal — usertty() destination Client-side failover
Routing messages: log paths, flags, and filters Global options of syslog-ng PE TLS-encrypted message transfer Advanced Log Transfer Protocol Reliability and minimizing the loss of log messages Manipulating messages parser: Parse and segment structured messages Processing message content with a pattern database Correlating log messages Enriching log messages with external data Monitoring statistics and metrics of syslog-ng Multithreading and scaling in syslog-ng PE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Glossary

Proxy Protocol support

If you connect load balancers to your syslog-ng PE application, syslog-ng PE identifies every connection that is connected to the load balancers identically by default, regardless of the source IP or the source protocol. Essentially, the load balancer masks the source IP unless you enable Proxy Protocol support for your proxy TLS transport() to inject information about the original connection into the forwarded TCP session.

For further details about the working mechanism behind the Proxy Protocol support on syslog-ng PE and the configuration details, see the following sections:


The working mechanism behind the Proxy Protocol

This section describes how syslog-ng Premium Edition (syslog-ng PE) supports the Proxy Protocol.

When using the Proxy Protocol during load balancing, syslog-ng PE detects the information behind connections connected to the load balancer, then parses the injected information and adds the following macros to every message the comes through the connection later on:

  • PROXY_SRCIP (the source IP of the proxy)

  • PROXY_SRCPORT (the source port of the proxy)

  • PROXY_DSTIP (the destination IP of the proxy)

  • PROXY_DSTPORT (the destination port of the proxy)

NOTE: Consider the following about macros and headers:

  • When the proxy protocol header is PROXY UNKNOWN, no additional macros are added.

  • When syslog-ng PE cannot parse a proxy protocol header, the connection is closed:

    [2020-11-20T17:33:22.189458] PROXY protocol header received; line='PROXYdsfj'
    [2020-11-20T17:33:22.189475] Error parsing PROXY protocol header;
    [2020-11-20T17:33:22.189517] Syslog connection closed; fd='13', client='AF_INET(', local='AF_INET('
    [2020-11-20T17:33:22.189546] Freeing PROXY protocol source driver; driver='0x7fffcba5bcf0'
    [2020-11-20T17:33:22.189600] Closing log transport fd; fd='13'

NOTE: Since the driver only implements version 1 of the protocol, it only supports TCP4 and TCP6 connections. TLS connections also supported.

Proxy Protocol: configuration and output examples

This section provides information about enabling Proxy Protocol support in your network() source options, and an example configuration and output to illustrate how the Proxy Protocol method works in syslog-ng Premium Edition (syslog-ng PE).

For more information about the working mechanism of the Proxy Protocol, see The working mechanism behind the Proxy Protocol.

Enabling Proxy Protocol support for your network() source options

Unless you enable Proxy Protocol support for your network() source, syslog-ng PE identifies every connection that is connected to the load balancers identically by default, regardless of the source IP or the source protocol.

To enable Proxy Protocol for your network() source, set the transport() parameter of your network() source to proxied_tcp or proxied_tls, depending on your preference and configuration.

When you enable Proxy Protocol support for your network() source, you can use the following configuration example with your syslog-ng PE application.


The following code sample illustrates how you can use the Proxy Protocol in your syslog-ng PE configuration (using the transport() parameter set to proxied_tls).

@version: 3.30

source s_tcp_pp {
  network (

destination d_file {
  file("/var/log/proxy-proto.log" template("$(format-json --scope nv-pairs)\n"));

log {

With this configuration, the Proxy Protocol method will perform injecting the information of the original connection into the forwarded TCP session, based on the working mechanism described in The working mechanism behind the Proxy Protocol.

The following example illustrates how the parsed macros will appear in the output.

Example: Output for the PROXY TCP4 1111 2222 input header

With the PROXY TCP4 1111 2222 input header, the output looks like this:


Note that the macros that syslog-ng PE adds to the message appear in the output.

office365: Fetching logs from Office 365

Starting with syslog-ng PE version 7.0.17, you can fetch logs from your Office 365 account using the Office 365 Management Activity API.

The syslog-ng PE application supports every content type of the Management Activity API using a corresponding source driver:

  • Audit.AzureActiveDirectory: office365-azure-active-directory()

  • Audit.Exchange: office365-exchange()

  • Audit.General: office365-general()

  • Audit.SharePoint: office365-sharepoint()

  • DLP.All: office365-dlp()

  • In some cases, the logs will appear only 24-48 hours after successfully configuring syslog-ng PE and Office 365.

  • Due to the distributed nature of the Office 365 log management architecture, there is a synchronization interval in the Office 365 Management Activity API. During this interval, the messages returned to queries can be inconsistent. To avoid this synchronization window, syslog-ng PE does not fetch the logs in real-time, only 15 minutes after the message becomes available in the management API. This means that there is a 15-minute latency between the logs available in the Office 365 Management Activity API and syslog-ng PE.

source s_office365 {
Example: Fetching Azure Active Directory logs from Office 365

The following example configuration fetches logs from and Audit.AzureActiveDirectory subscription using the office365-azure-active-directory() source driver.

@version: 7.0
@include "scl.conf"

source s_o365_ad {

destination d_file { file("/tmp/o365_ad_out.log"); };

log {
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