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syslog-ng Premium Edition 7.0.32 - 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 google_pubsub-managedaccount(): Sending logs to the Google Cloud Pub/Sub messaging service authenticated by Google Cloud managed service account hdfs: Storing messages on the Hadoop Distributed File System (HDFS) http: Posting messages over HTTP kafka(): Publishing messages to Apache Kafka (Java implementation) (DEPRECATED) kafka-c(): Publishing messages to Apache Kafka using the librdkafka client (C implementation) 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 Transport 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

Mutual authentication using TLS

This section describes how to configure mutual authentication between the syslog-ng server and the client. Configuring mutual authentication is similar to configuring TLS (for details, see Encrypting log messages with TLS), but the server verifies the identity of the client as well. Therefore, each client must have a certificate, and the server must have the certificate of the CA that issued the certificate of the clients. For the concepts of using TLS in syslog-ng, see Secure logging using TLS.

Configuring TLS on the syslog-ng clients

Complete the following steps on every syslog-ng client host. Examples are provided using both the legacy BSD-syslog protocol (using the network() driver) and the new IETF-syslog protocol standard (using the syslog() driver):

To configure TLS on the syslog-ng clients

  1. Create an X.509 certificate

    Create an X.509 certificate for the syslog-ng client.

  2. Copy the certificate and private key

    Copy the certificate (for example, client_cert.pem) and the matching private key (for example, client.key) to the syslog-ng client host, for example, into the /opt/syslog-ng/etc/syslog-ng/cert.d directory. The certificate must be a valid X.509 certificate in PEM format. If you want to use a password-protected key, see Password-protected keys.

  3. Copy the CA certificate to the client host

    Copy the CA certificate of the Certificate Authority (for example, cacert.pem) that issued the certificate of the syslog-ng server (or the self-signed certificate of the syslog-ng server) to the syslog-ng client hosts, for example, into the /opt/syslog-ng/etc/syslog-ng/ca.d directory.

  4. Issue commands

    Issue the following command on the certificate: openssl x509 -noout -hash -in cacert.pem The result is a hash (for example, 6d2962a8), a series of alphanumeric characters based on the Distinguished Name of the certificate.

    Issue the following command to create a symbolic link to the certificate that uses the hash returned by the previous command and the .0 suffix.

    ln -s cacert.pem 6d2962a8.0

  5. Add a destination statement

    Add a destination statement to the syslog-ng configuration file that uses the tls( ca-dir(path_to_ca_directory) ) option and specify the directory using the CA certificate. The destination must use the network() or the syslog() destination driver, and the IP address and port parameters of the driver must point to the syslog-ng server. Include the client's certificate and private key in the tls() options.

    Example: A destination statement using mutual authentication

    The following destination encrypts the log messages using TLS and sends them to the 1999/TCP port of the syslog-ng server having the 10.1.2.3 IP address. The private key and the certificate file authenticating the client is also specified.

    destination demo_tls_destination {
    network("10.1.2.3" port(1999)
        transport("tls")
        tls( ca-dir("/opt/syslog-ng/etc/syslog-ng/ca.d")
             key-file("/opt/syslog-ng/etc/syslog-ng/key.d/client.key")
             cert-file("/opt/syslog-ng/etc/syslog-ng/cert.d/client_cert.pem")) ); };
    destination demo_tls_syslog_destination {
    syslog("10.1.2.3" port(1999)
        transport("tls")
            tls( ca-dir("/opt/syslog-ng/etc/syslog-ng/ca.d")
                 key-file("/opt/syslog-ng/etc/syslog-ng/key.d/client.key")
                 cert-file("/opt/syslog-ng/etc/syslog-ng/cert.d/client_cert.pem")) ); };

  6. Include destination in a log statement

    Include the destination created in the Step Add a destination statement in a log statement.

    		 Caution:

    The encrypted connection between the server and the client fails if the Common Name or the subject_alt_name parameter of the server certificate does not contain the hostname or the IP address (as resolved from the syslog-ng clients and relays) of the server.

    Do not forget to update the certificate files when they expire.

Configuring TLS on the syslog-ng server

Complete the following steps on the syslog-ng server:

To configure TLS on the syslog-ng clients

  1. Copy the certificate (for example, syslog-ng.cert) of the syslog-ng server to the syslog-ng server host, for example, into the /opt/syslog-ng/etc/syslog-ng/cert.d directory. The certificate must be a valid X.509 certificate in PEM format.

  2. Copy the CA certificate (for example, cacert.pem) of the Certificate Authority that issued the certificate of the syslog-ng clients to the syslog-ng server, for example, into the /opt/syslog-ng/etc/syslog-ng/ca.d directory.

    Issue the following command on the certificate: openssl x509 -noout -hash -in cacert.pem The result is a hash (for example, 6d2962a8), a series of alphanumeric characters based on the Distinguished Name of the certificate.

    Issue the following command to create a symbolic link to the certificate that uses the hash returned by the previous command and the .0 suffix.

    ln -s cacert.pem 6d2962a8.0

  3. Copy the private key (for example, syslog-ng.key) matching the certificate of the syslog-ng server to the syslog-ng server host, for example, into the /opt/syslog-ng/etc/syslog-ng/key.d directory. The key must be in PEM format. If you want to use a password-protected key, see Password-protected keys.

  4. Add a source statement to the syslog-ng configuration file that uses the tls( key-file(key_file_fullpathname) cert-file(cert_file_fullpathname) ) option and specify the key and certificate files. The source must use the source driver (network() or syslog()) matching the destination driver used by the syslog-ng client. Also specify the directory storing the certificate of the CA that issued the client's certificate.

    For the details of the available tls() options, see TLS options.

    Example: A source statement using TLS

    The following source receives log messages encrypted using TLS, arriving to the 1999/TCP port of any interface of the syslog-ng server.

    source demo_tls_source {
    network(ip(0.0.0.0) port(1999)
        transport("tls")
               tls( key-file("/opt/syslog-ng/etc/syslog-ng/key.d/syslog-ng.key")
                    cert-file("/opt/syslog-ng/etc/syslog-ng/cert.d/syslog-ng.cert")
                    ca-dir("/opt/syslog-ng/etc/syslog-ng/ca.d")) ); };

    A similar source for receiving messages using the IETF-syslog protocol:

    source demo_tls_syslog_source {
                        syslog(ip(0.0.0.0) port(1999)
                        transport("tls")
                        tls( key-file("/opt/syslog-ng/etc/syslog-ng/key.d/syslog-ng.key")
                        cert-file("/opt/syslog-ng/etc/syslog-ng/cert.d/syslog-ng.cert")
                        ca-dir("/opt/syslog-ng/etc/syslog-ng/ca.d")) ); };

    		 Caution:

    Do not forget to update the certificate and key files when they expire.

Password-protected keys

Starting with syslog-ng PE version 7.0.7, you can use password-protected private keys in the network() and syslog() source and destination drivers.

Restrictions and limitations

  • IMPORTANT: Hazard of data loss! If you use password-protected keys, you must provide the passphrase of the password-protected keys every time syslog-ng PE is restarted (syslog-ng PE keeps the passphrases over reloads). The sources and destinations that use these keys will not work until you provide the passwords. Other parts of the syslog-ng PE configuration will be unaffected.

    This means that if you use a password-protected key in a destination, and you use this destination in a log path that has multiple destinations, neither destinations will receive log messages until you provide the password. In this cases, always use the disk-buffer option to avoid data loss.

  • The path and the filename of the private key cannot contain whitespaces.

  • Depending on your platform, the number of passwords syslog-ng PE can use at the same time might be limited (for example, on Ubuntu 16.04 you can store 16 passwords if you are running syslog-ng PE as a non-root user). If you use lots of password-protected private keys in your syslog-ng PE configuration, increase this limit using the following command: sudo ulimit -l unlimited

Providing the passwords

The syslog-ng-ctl credentials status command allows you to query the status of the private keys that syslog-ng PE uses in the network() and syslog() drivers. The command returns the list of private keys used, and their status. For example:

syslog-ng-ctl credentials status
Secret store status:
/home/user/ssl_test/client-1/client-encrypted.key SUCCESS

If the status of a key is PENDING, you must provide the passphrase for the key, otherwise syslog-ng PE cannot use it. The sources and destinations that use these keys will not work until you provide the passwords. Other parts of the syslog-ng PE configuration will be unaffected. You must provide the passphrase of the password-protected keys every time syslog-ng PE is restarted.

The following log message also notifies you of PENDING passphrases:

Waiting for password; keyfile='private.key'

You can add the passphrase to a password-protected private key file using the following command. syslog-ng PE will display a prompt for you to enter the passphrase. We recommend that you use this method.

syslog-ng-ctl credentials add --id=<path-to-the-key>

Alternatively, you can include the passphrase in the --secret parameter:

syslog-ng-ctl credentials add --id=<path-to-the-key> --secret=<passphrase-of-the-key>

Or you can pipe the passphrase to the syslog-ng-ctl command, for example:

echo "<passphrase-of-the-key>" | syslog-ng-ctl credentials add --id=<path-to-the-key>

For details on the syslog-ng-ctl credentials command, see The syslog-ng control tool manual page.

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