The syslog-ng Administrator Guide

Procedure 3.3. Configuring TLS on the syslog-ng clients

1. Create an X.509 certificate for the syslog-ng client. The subject_alt_name parameter (or the Common Name parameter if the subject_alt_name parameter is empty) must contain the hostname or the IP address (as resolved from the syslog-ng clients and relays) of the client.

2. Copy the certificate (e.g., client_cert.pem) and the matching private key (e.g., client.key) to the syslog-ng client host, for example into the /etc/syslog-ng/cert.d directory. The certificate must be a valid X.509 certificate in PEM format and must not be password-protected.

3. Copy the CA certificate of the Certificate Authority (e.g., cacert.pem) that issued the certificate of the syslog-ng server to the syslog-ng client hosts, for example into the /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 (e.g., 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

4. 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 tcp() or tcpv6() 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 3.13. A destination statement 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 { tcp("10.1.2.3" port(1999) tls( ca_dir("/etc/syslog-ng/ca.d") key_file("/etc/syslog-ng/key.d/client.key") cert_file("/etc/syslog-ng/cert.d/client_cert.pem")) ); };

5. Include the destination created in Step 2 in a log statement.

   	Warning
   	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 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.

Procedure 3.4. Configuring TLS on the syslog-ng server

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

2. Copy the CA certificate (e.g., cacert.pem) of the Certificate Authority that issued the certificate of the syslog-ng clients to the syslog-ng server, for example into the /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 (e.g., 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 (e.g., syslog-ng.key) matching the certificate of the syslog-ng server to the syslog-ng server host, for example into the /etc/syslog-ng/key.d directory. The key must be in PEM format, and must not be password-protected.

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 (tcp() or tcpv6()) 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.

   	Example 3.14. 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 { tcp(ip(0.0.0.0) port(1999) tls( key_file("/etc/syslog-ng/key.d/syslog-ng.key") cert_file("/etc/syslog-ng/cert.d/syslog-ng.cert") ca_dir("/etc/syslog-ng/ca.d")) ); };

   	Warning
   	The encrypted connection between the server and the client fails if the Common Name or the subject_alt_name parameter of the client certificate does not 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 and key files when they expire.