tc_reader

A persistent SNMP script that exports TC Queue and Class statistics for graphing (for example to Cacti).

If you ever needed to setup proper QoS configuration on your Linux based router and then wondered how to monitor the individual Queue / Class statistics or even better monitor individual users, you probably know the pain. You either ended being disappointed or implemented your own solution.

If you are from the former group of users, this project might be for you.

What is tc_reader ?

The tc_reader acts as a persistent script for the Net-SNMP agent. See man SNMPD.CONF(5snmp) for more details on persistent scripts. It is started by the SNMP daemon and it regularly runs iproute2/tc command to get all the queue and class statistics. These statistics are then provided to the SNMP daemon whenever SNMP GET or GET-NEXT query is made to the OID that is served by the tc_reader.

The tc_reader is written in Go in order to be fast and reliable.

Installation

1. Get the binary: You have two options. You can either take one of the pre-compiled binaries, or get the latest version of the source code directly from github.com and compile it yourself.

2. Configure tc_reader: Take the sample configuration file and adjust it to match your needs.

3. Configure SNMPD: After you have the binary, you need to have a working Net-SNMP agent and configure the tc_reader as a persistent script.

4. Add the graphs: Lastly you might want to start graphing the statistics in your favorite monitoring solution. Example for Cacti is provided.

Get the binary - Method 1 - Download pre-compiled binaries

Sorry, no binary releases yet, coming soon...

Get the binary - Method 2 - The do-it-yourself method

1. You will need a working Go installation on your machine. On Debian/Ubuntu you can achieve this by running:

   apt-get install golang
   

2. Next you need to set-up the $GOPATH environment variable. See the article How to Write Go Code for more details. What you need to do is choose a directory where all the Go code and binaries will be stored. Say that you choose /home/your_username/go. Run the following:

   mkdir /home/$USER/go
   export GOPATH="/home/$USER/go"
   

3. You can now get the latest copy of this source-code from GitHub:

   go get github.com/mum4k/tc_reader
   

4. Now to compile and install the binary run:

   go install github.com/mum4k/tc_reader
   

5. You can find the compiled binary in /home/your_username/go/bin/tc_reader. Either keep it here or move it somewhere else on your system based on your preference.

Test the binary

See if it works. Your can execute the binary and write PING on the empty line. Assuming that everything is OK, tc_reader should respond PONG. Yeah do not judge me, this is the SNMPD standard for communication with persistent scripts.

Configure tc_reader

Get the tc_reader.conf file. If you downloaded one of the pre-compiled binaries, you will find it inside the archive. If you compiled the binary yourself, you will find it inside the $GOPATH. You have to copy the tc_reader.conf file into your /etc/ directory:

cp /home/$USER/go/src/github.com/mum4k/tc_reader/tc_reader.conf /etc

The configuration file is self-explanatory (hopefully).

Configure SNMPD

The assumption is that you already have a working setup of Net-SNMP daemon and the SNMP client utilities (snmpwalk, ...). The bare minimum is:

apt-get install snmpd snmp

Edit your Net-SNMP configuration file, which is usually located in /etc/snmp/snmpd.conf. You have to add one line:

pass_persist .1.3.6.1.4.1.2021.255 /path/to/tc_reader

Restart and test SNMPD

Restart your Net-SNMP daemon. On Debian/Ubuntu you could execute:

service snmpd restart

Now try to query the Net-SNMP daemon and see if everything up to here works:

snmpwalk -v2c -c your_community localhost .1.3.6.1.4.1.2021.255

Add the graphs Cacti.

You might need to perform different steps if you are using some other software for graphing. However if you use Cacti, you can follow these steps to monitor individual users configured in tc_reader.conf.

1. Copy the snmp_queries templates into your cacti resource directory. Example:

cp /home/$USER/go/src/github.com/mum4k/tc_reader/cacti_templates/snmp_queries/* /usr/share/cacti/resource/snmp_queries

2. Login to your Cacti console, click on Import Templates in the menu and import the data query templates from this directory:

/home/$USER/go/src/github.com/mum4k/tc_reader/cacti_templates/data_queries

3. In Cacti console, click on Devices, then your device and down under Associated Data Queries add a data query called SNMP - TC Users. Once this is added to your device you can click on Verbose Query to see if it works.

4. Finally, still on the same device page click on Create Graphs for this host, on the next page under SNMP - TC Users select all the users you would like to monitor and click Create.

Assuming that all of this worked - enjoy the graphs.

Support

Feel free to submit bugs or let me know if you find anything wrong or missing. Although this is a "pet-project" so expect some delays.