TNSR-IDS Project

Provide high-speed traffic copies and in-band enforcement to your Intrusion Detection System (IDS).
TNSR + Snort
SETUP v1.3


Get familiar with the functions and commands to get your IDS set up and running.



Configure your IDS to make sure it is working specifically for your network's unique needs. 



With TNSR software now powering your Snort IDS you can rest easy knowing your network is vigilantly protected and secure.

 IDS map


TNSR-IDS Project


Netgate's TNSR is a high-speed packet processing engine. It enables secure networking at speeds up to 100 Gbps and more - at a fraction of the price of proprietary alternatives. You can learn more about TNSR here.

This project was developed to show how TNSR can support out-of-band packet inspection/analysis engines with 1) a fast traffic copy function, and 2) an ability to receive policy enforcement commands over an API and subsequently perform in-band enforcement.

Customers capable of designing and implementing networking and/or security solutions with open- or closed-source packet inspection functions can leverage TNSR's power to more cost-effectively address large-scale packet processing needs.

In this specific project, TNSR-enabled IDS demonstrates remote configuration via RESTCONF by automatically adding Access Control List (ACL) block rules in response to alert messages received from a Snort instance running in intrusion detection mode.





ERSPAN is configured to forward a copy of all WAN port traffic to SNORT. SNORT analyzes the traffic and produces alert messages in syslog format when intrusions are detected. Those alert messages are tramsmitted to tnsrids which emulates a syslog server, listening on a configurable UDP port.

When tnsrids receives an alert message, the source IP address is extracted and a new ACL rule is constructed to block traffic from that source. The program then installs the rule in the TNSR ACL causing traffic from that source to be blocked.

The block rules added in this way have a lifetime of 60 minutes (configurable) and are automatically deleted after that time tnsrids/TNSR/SNORT can be used in several topologies: All on one machine, each on a different machine, multiple instances of SNORT all feeding the same tnsrids, or any permutation thereof.

Instructions for setting up TNSR and SNORT to accompany tnsrids can be found here:



Several command line switches are supported:

  • -v Verbose mode. Outputs useful (maybe) messages while running
  • -p UDP port to listen on for Syslog messages (Defaults to 12345)
  • -h Specify TNSR RESTCONF address (Defaults to localhost)
  • -c Configuration file location (Defaults to /etc/tnsrids/tnsrids.conf)
  • -m Maximum age of added rules in minutes before deletion (Defaults to 60, 0 = never)
  • -show Display the current ACL in table format and quit
  • -reap Delete ACL rules older than minutes (default=60)
  • -ca TLS Certificate authority file path (Defaults to /etc/tnsrids/.tls/ca.crt)
  • -cert TLS Certificate file path (Defaults to /etc/tnsrids/.tls/tnsr.crt)
  • -key TLS key file path (Defaults to /etc/tnsrids/.tls/tnsr.key)


Configuration file

Several options may be set via configuration file. The default location is /etc/tnsrids/tnsrids.conf, but that can be overridden on the command line with the -c switch

Currently these values may be set. More will follow:

  • host (location of TNSR instance - including protocol)
  • port (UDP port to listen on)
  • maxage (Maximum age of rules before they are reaped, 0 = never)
  • ca (Location ofcertificate authority file)
  • cert (Location of TLS client certificate)
  • key (Location of TLS key)

The configuration keys are case insensitive. See the sample tnsrids.conf for more details

When a configuration value is provided on the command line AND in the config file, the command line wins.



To build natively:
 go build

To cross-compile:
 GOOS=linux GOARCH=amd64 go build 

Or other OS/architectures as needed. A list of available target OS/ARCH can be found here:


To build without debug info or labels:

Append  -ldflags "-s -w"  to the build command



tnsrids can be run as an application or a service. To install it as a service, copy tnsrids to /usr/local/sbin, copy the file tnsrids.service to /lib/systemd/system, then type:

 sudo systemctl enable tnsrids 
sudo systemctl start tnsrids


Firewall considerations

TNSR version 19.02 and later ships with nftables enabled and configured. If the TNSR-IDS utility is run on the same machine as the TNSR instance a rule MUST be added to allow TNSR-IDS to receive the UDP datagrams produced by Snort. Specifying the UDP port you have configured TNSR-IDS to listen on (12345 used in this example) add a rule like so:

sudo nft add rule inet tnsr_filter tnsr_input_mgmt_default udp dport 12345 accept

You can verify that the rule has been added by listing all tables:

sudo nft list table inet tnsr_filter -a 


TLS authentication

Best practices dictate that TLS authentication is used to connect to the TNSR RESTCONF interface. Three files are required to authenticate in this way: A certificate authority, a client certificate and a key. The location of those files may be specified in the config file or on the command line. The default location is /etc/tnsrids/.tls/ - The full path and filename is required for each file.

If tnsrids is running on the same machine as TNSR TLS authentication may not needed. In that case, specifying a TNSR address with "http://" rather than "HTTPS://" will disable TLS negotiation



The command go test -v will exectute the program unit tests (in tnsrids_test.go) - Tests are provided for various utility functions. It would be possible to provide Go tests for the network pieces too, but "standard" test tools such as cURL and netcat are simpler and "standard" is a good thing.


Running tnsrids in a Docker container

There are a number of ways in which tnsrids can be run in a Docker container. These include:

  • Include all of the resources required by tnsrids (config file and certificates) in the Docker image
  • Leave the resource files in a directory on the host machine, mounting the directory inside the container and passing in configuration options via command line options
Inclusive method

The "include the resources in the image" method is the most simple. Assuming that Docker has been installed on the host system (sudo yum install docker or equivalent), perform the following steps:

  1. Build a copy of the tnsrids utility for a Linux target GOOS=linux GOARCH=amd64 go build tnsrids
  2. Create a directory to hold everything required by the Docker image and place the following files therein:
    • The newly built Linux tnsrids
    • The configuration file tnsrids.conf
    • ca.crt
    • tnsrids.crt
    • tnsrids.key
    • The file Dockerfile_inclusive from this repository, which MUST be renamed to simply "Dockerfile"
  3. Now change directories to the new directory and build the Docker image with docker build --tag tnsrids .

IMPORTANT NOTE The file names used for the configuration file, ca, certificate and key must all match the names used in the Dockerfile and in the configuration file.

To run the Docker image use the command docker run -p 12345:12345/udp tnsrids:latest where the published port corresponds to the UDP port in the tnsrids configuration file.

Host-based configuration
  1. Build a copy of the tnsrids utility for a Linux target GOOS=linux GOARCH=amd64 go build tnsrids
  2. Create a directory to hold everything required by the Docker image and place the following files therein:
    • The newly built Linux tnsrids
    • The configuration file tnsrids.conf
    • ca.crt
    • tnsrids.crt
    • tnsrids.key
    • The file Dockerfile_host from this repository, whuch MUST be renamed to simply "Dockerfile"
  3. Edit the Dockerfile changing the location of the certificate, ca and key files to /mnt/tnsrids
  4. Now change directories to the new directory and build the Docker image with docker build --tag tnsrids .

To run the Docker image use the command: docker run <path to new folder on host>:/mnt/tnsrids -p 12345:12345/udp tnsrids:latest tnsrids -c /mnt/tnsrids.conf

This command tells Docker to mount the directory you made inside the container as /mnt/tnsrids and then to read the configuration file from that directory.

Running a Docker container as a service at start-up

Please refer to this Red Hat systemd guide The tnsrids-docker.service file in this repository is correctly configured per the website example.

Get Started With TNSR

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