omdtls: Output Module for DTLS Protocol over UDP¶

Module Name:	omdtls
Author:	Andre Lorbach <alorbach@adiscon.com>
Available since:	v8.2402.0

Purpose¶

The omdtls module for rsyslog is designed to securely transmit syslog data over a network using the Datagram Transport Layer Security (DTLS) protocol. This module leverages the robustness and security features of OpenSSL to provide an encrypted transport mechanism for syslog messages via UDP.

DTLS, being an adaptation of TLS for datagram-based protocols, offers integrity, authenticity, and confidentiality for messages in transit. The omdtls module is particularly useful in environments where secure transmission of log data is crucial, such as in compliance-driven industries or when transmitting across untrusted networks.

By operating over UDP, omdtls offers the benefits of lower latency and reduced protocol overhead compared to TCP-based transport, making it well-suited for high-throughput logging scenarios or in networks where connection-oriented protocols may face challenges.

Requirements¶

To send messages by DTLS you will need to fulfill the following requirements:

OpenSSL 1.0.2 or Higher

Configuration Parameters¶

Note

Parameter names are case-insensitive; camelCase is recommended for readability.

Module Parameters¶

Parameter	Summary
template	Selects the template used to format messages sent through omdtls actions.

Action Parameters¶

Parameter	Summary
target	Specifies the destination host name or IP address for omdtls.
port	Sets the UDP port on the remote host that receives DTLS messages.
template	Selects the template used to format messages sent through omdtls actions.
tls.authmode	Sets the DTLS peer authentication method used by the action.
tls.cacert	Defines the CA certificate used to verify client certificates.
tls.mycert	Specifies the certificate file presented by omdtls during the DTLS handshake.
tls.myprivkey	Provides the private key that matches `tls.mycert` for DTLS authentication.
tls.tlscfgcmd	Passes additional OpenSSL configuration commands to fine-tune DTLS behavior.
statsname	Enables a dedicated per-action statistics counter identified by the provided name.

Statistic Counter¶

This plugin maintains global statistics for omdtls that accumulate all action instances. The statistic origin is named “omdtls” with following counters:

submitted - This counter tracks the number of log messages that have been successfully send by the current output instance.
failures - This counter tracks the number of log messages that have been failed to send to the target server.

These statistics counters are updated in real-time by the rsyslog output module as log data is processed, and they provide valuable information about the performance and operation of the input module.

For multiple actions using statistics callback, there will be one record for each action.

Examples¶

Example 1: Basic¶

The following sample does the following: - loads the omdtls module - Sends all syslog messages to 192.168.2.1 by DTLS on port 4433.

module(load="omdtls")
action(type="omdtls" name="omdtls" target="192.168.2.1" port="4433")

Example 2: Message throttling¶

The following sample does the following:

loads the omdtls module
Sends all syslog messages to 192.168.2.1 by DTLS on port 4433.
Slows down sending to avoid package loss due the nature of UDP. In this sample, using dequeueSlowDown 1000 will limit the messages per second to 1000.

module(load="omdtls")
action(type="omdtls"
    name="omdtls"
    target="192.168.2.1"
    port="4433"
    queue.type="FixedArray"
    queue.size="100000"
    queue.dequeueBatchSize="1"
    queue.minDequeueBatchSize.timeout="1000"
    queue.timeoutWorkerthreadShutdown="1000"
    queue.timeoutshutdown="1000"
    queue.dequeueSlowDown="1000"
)

Support: rsyslog Assistant | GitHub Discussions | GitHub Issues: rsyslog source project

Contributing: Source & docs: rsyslog source project