{"id":1199,"date":"2017-12-28T19:06:22","date_gmt":"2017-12-28T13:36:22","guid":{"rendered":"https:\/\/www.booleanworld.com\/?p=1199"},"modified":"2018-03-15T21:10:17","modified_gmt":"2018-03-15T15:40:17","slug":"monitor-network-traffic-linux-using-vnstat","status":"publish","type":"post","link":"https:\/\/www.booleanworld.com\/monitor-network-traffic-linux-using-vnstat\/","title":{"rendered":"How to Monitor Network Traffic on Linux Using vnStat"},"content":{"rendered":"

\"vnstat<\/p>\n

Developers and sysadmins may need to monitor various network parameters, such as bandwidth consumption and the traffic flowing in\/out. There are many tools available for this purpose, one of them being vnStat. It is a simple CLI utility that shows network statistics over various interfaces and periods for a particular computer. In this article, we will see how to install and work with vnStat, and (optionally) view this data graphically using vnstat-dashboard.<\/p>\n

Installation<\/h2>\n

For Ubuntu and Debian systems, vnStat is available in the default repository. Use the following commands in order to install it:<\/p>\n

sudo<\/span> apt update\r\nsudo<\/span> apt install vnstat<\/pre>\n
The default repositories for CentOS and Fedora don’t have vnStat, but you can get them from the EPEL<\/a> repositories. Thus, you should enable the EPEL repositories, and then install vnStat. Use the following commands to do so:<\/p>\n
sudo<\/span> yum install epel-release\r\nsudo<\/span> yum install vnstat<\/pre>\n
For Fedora systems, type in the following:<\/p>\n
sudo<\/span> dnf update\r\nsudo<\/span> dnf\u00a0install vnstat<\/pre>\n
Setting up vnStat<\/h2>\n
After installing vnStat, you have to set the network interface which you want to monitor. However, first you need to know the list of network interfaces available on our system before you can ask vnStat to monitor it. To do so, use any of the two commands:<\/p>\n
ip<\/span> link show<\/pre>\n
or<\/p>\n
netstat<\/span>\u00a0-i<\/pre>\n
This will show a list of all network interfaces available in the system.<\/p>\n
\"List<\/p>\n
For this article, we will just monitor the interface representing Ethernet connection to our system, which is eth0<\/code> in our example. On your system, you may find the interface named differently, such as enp0s3<\/code> or venet0<\/code>. If you use WiFi, there will be a interface such as wlan0<\/code> or wifi0<\/code>. Any interfaces with names like lo<\/code> or lo0<\/code> represent the loopback interface<\/a>, which is used for local traffic, such as communication between daemons.<\/p>\n
So, to select the eth0<\/code>\u00a0 interface for monitoring, use the command:<\/p>\n
sudo<\/span> vnstat -u -i eth0<\/pre>\n
It should tell you that a database has been created. Then, you should set proper permissions for the database with:<\/p>\n
sudo<\/span> chown -R vnstat: \/var\/lib\/vnstat<\/pre>\n
Finally, enable and restart the daemon with:<\/p>\n
sudo<\/span> systemctl enable vnstat\r\nsudo<\/span> systemctl restart vnstat<\/pre>\n
You can verify that the daemon is running with top<\/a>, or with systemctl status<\/code>:<\/p>\n
sudo<\/span> systemctl status vnstat<\/pre>\n
 <\/p>\n
\"\"<\/h2>\n
Viewing bandwidth consumption<\/h2>\n
By default, vnStat writes fresh statistics to the database every 30 seconds. After waiting for 30 seconds, run vnstat<\/code> to view the monthly and daily statistics in a tabular form. If your system doesn’t receive too much traffic, you can try downloading these files<\/a> to generate some traffic before viewing the statistics.<\/p>\n
\"vnStat<\/p>\n
The “rx” and “tx” columns show the received and transmitted traffic respectively, and the “total” column gives the sum of these two values. The “avg. rate” shows the average rate of bandwidth consumption per second, over the course of the day or month.<\/p>\n
Sometimes, you may want to see the updated bandwidth usage immediately without waiting. In that case, you can force vnStat to update the database with:<\/p>\n
sudo<\/span> vnstat -u<\/pre>\n
Then, run vnstat<\/code> as usual; you will get to see the updated statistics after you do so.<\/p>\n
If you want to view statistics for a different timeframe, there are different switches you can use:<\/p>\n