In this tutorial, we will see what is vnStat, how to install vnStat and then how to monitor network bandwidth using vnStat in Linux and BSD operating systems.
Table of Contents
vnStat Introduction
VnStat is a free, open source, light-weight, and console-based Network Traffic monitor. Using VnStat, we can easily find how much network bandwidth is consumed and display the result hourly, daily, monthly, or for specific time period.
Vnstat gathers the usage details of a single or multiple Network interfaces and displays the summary in the command line. It also helps to calculate the approximate amount of Internet bandwidth usage per month or per day or for a particular period of time.
Install vnStat in Linux
VnStat is available in the default repositories of many Linux and Unix operating systems. You can install it using your distribution's package manager.
On Arch based systems:
Make sure you have enabled [Community] repository and install it using pacman like below:
$ sudo pacman -S vnstat
On Debian, Ubuntu, Linux Mint, Pop OS:
$ sudo apt install vnstat
On Ubuntu you may need to enable [Universe] repository to install vnstat.
On Redhat, CentOS, AlmaLinux, Rocky Linux:
Add and Enable EPEL repository first:
$ sudo dnf install epel-release
And then install vnStat as shown above.
$ sudo dnf install vnstat
On Fedora:
$ sudo dnf install vnstat
On openSUSE:
$ sudo zypper install vnstat
After installed vnStat, start its service using command:
$ sudo systemctl enable --now vnstat
You don't need to start vnstat on DEB-based systems, as it is automatically enabled and started after installing vnStat.
Install vnStat in FreeBSD
On BSD systems like freeBSD, update port tree and install vnStat as root user using commands:
# pkg update
# pkg install vnstat
Once installed, enable and start vnStat service like below.
# echo 'vnstat_enable="YES"' >> /etc/rc.conf
# service vnstat start
Sample output:
Starting vnstat. No interfaces found in database, adding available interfaces... Interface "em0" added with 1000 Mbit bandwidth limit. -> 1 new interface found. Limits can be modified using the configuration file. See "man vnstat.conf". Unwanted interfaces can be removed from monitoring with "vnstat --remove".".
Configure Default Network Interface on Linux
vnStat uses eth0 as default network interface in its configuration file (/etc/vnstat.conf).
However, in some Linux systems (e.g. Ubuntu), the network interface name might be different, like enp0s3, enp0s8. You can verify the network interface's name using "ip addr" command.
Let us have a look at the contents of vnstat config file.
$ head /etc/vnstat.conf
Sample output:
# vnStat 1.18 config file
##
# default interface
Interface "eth0"
# location of the database directory
DatabaseDir "/var/lib/vnstat"
# locale (LC_ALL) ("-" = use system locale)As you can see, the default interface is etho in this file.
Let us check the available network interfaces identified by vnstat.
$ ls /var/lib/vnstat enp0s3 enp0s8
As you see, the available network interfaces are different than the one defined in vnstat.conf file.
If you don't set correct default interface, you might get the following error when viewing network bandwidth traffic hourly or monthly.
Error: Unable to read database "/var/lib/vnstat/eth0": No such file or directory
This happens because, the default interface is incorrectly defined in the /etc/vnstat.conf file.
To configure default network interface, edit /etc/vnstat.conf file and update the correct interface name. You can directly edit /etc/vnstat.conf file and update the interface name globally. However, it is recommended to create your own vnstat config file in the user's HOME directory.
$ cp /etc/vnstat.conf ~/.vnstatrc
$ nano ~/.vnstatrc
I am going to use enp0s3 as my default interface.
Replace enp0s3 with your own. Save and close the file.
Configure Default Network Interface in FreeBSD
Edit vnstat configuration file:
# vi /usr/local/etc/vnstat.conf
If the config file is not available, create a new one using sample configuration file:
# cp /usr/local/etc/vnstat.conf.sample /usr/local/etc/vnstat.conf
Then, update the correct default network interface:
Interface "em0"
Save and close the file.
Monitor Network Bandwidth using vnStat in Linux and Unix
If you are new to vnStat, bring up the help section of vnStat and see the list of available options by running this command:
$ vnstat --help
Sample output:
vnStat 1.18 by Teemu Toivola <tst at iki dot fi>
-q, --query query database
-h, --hours show hours
-d, --days show days
-m, --months show months
-w, --weeks show weeks
-t, --top10 show top 10 days
-s, --short use short output
-u, --update update database
-i, --iface select interface (default: eth0)
-?, --help short help
-v, --version show version
-tr, --traffic calculate traffic
-ru, --rateunit swap configured rate unit
-l, --live show transfer rate in real time
See also "--longhelp" for complete options list and "man vnstat".Viewing Bandwidth Usage of all Interfaces
Now, Let us display the Network traffic of all interfaces.
To do so, just run:
$ vnstat
Sample output:
rx / tx / total / estimated
enp0s3:
Sep '19 120 KiB / 66 KiB / 186 KiB / 0 KiB
today 120 KiB / 66 KiB / 186 KiB / --
enp0s8:
Sep '19 128 KiB / 88 KiB / 216 KiB / 0 KiB
today 128 KiB / 88 KiB / 216 KiB / --
Here,
rx- The received traffictx- The transferred traffic
Allow a few minutes for Vnstat to start gathering the network traffic usage. If you start vnstat immediately right after installing it, you may get a result something like below.
enp0s3: Not enough data available yet.
Or, you will get the following output in RPM based distributions such as CentOS.
No database found, nothing to do. Use --help for help. A new database can be created with the following command: vnstat --create -i eth0 Replace 'eth0' with the interface that should be monitored. The following interfaces are currently available: enp0s3 (1000 Mbit) lo
It displays nothing now. It is because, vnStat is not yet started to collect the statistics.
Viewing Bandwidth Usage of a Particular Interface
To view the network bandwidth usage of a particular interface, for example enp0s3, just mention the Network card name like below.
$ vnstat -i enp0s3
Sample output:
Database updated: Mon Sep 9 08:26:47 2019
enp0s3 since 09/09/2019
rx: 136 KiB tx: 74 KiB total: 210 KiB
monthly
rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
Sep '19 136 KiB | 74 KiB | 210 KiB | 0.00 kbit/s
------------------------+-------------+-------------+---------------
estimated -- | -- | -- |
daily
rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
today 136 KiB | 74 KiB | 210 KiB | 0.06 kbit/s
------------------------+-------------+-------------+---------------
estimated -- | -- | -- |
Here, enp0s3 is my network card name. You can find your network card name using "ip addr" command.
On FreeBSD, the network card name is em0. To view its bandwidth, simply run:
# vnstat -i em0
Sample output:
Database updated: 2019-09-09 16:40:00
em0 since 2019-09-09
rx: 606.84 KiB tx: 56.12 KiB total: 662.96 KiB
monthly
rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
2019-09 606.84 KiB | 56.12 KiB | 662.96 KiB | 7 bit/s
------------------------+-------------+-------------+---------------
estimated -- | -- | -- |
daily
rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
today 606.84 KiB | 56.12 KiB | 662.96 KiB | 90 bit/s
------------------------+-------------+-------------+---------------
estimated 873 KiB | 80 KiB | 953 KiB
Viewing Bandwidth Usage Per Hour
Let us display the Network traffic results per hour. To do so, run:
$ vnstat -h
Sample output:
enp0s3 09:46
^ r
| r r
| r r
| r r
| r r r
| rt rt r
| rt rt r
| rt rt rt
| rt rt rt
| r rt rt rt
-+--------------------------------------------------------------------------->
| 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09
h rx (KiB) tx (KiB) ][ h rx (KiB) tx (KiB) ][ h rx (KiB) tx (KiB)
10 0 0 ][ 18 0 0 ][ 02 0 0
11 0 0 ][ 19 0 0 ][ 03 0 0
12 0 0 ][ 20 0 0 ][ 04 0 0
13 0 0 ][ 21 0 0 ][ 05 0 0
14 0 0 ][ 22 0 0 ][ 06 12 7
15 0 0 ][ 23 0 0 ][ 07 86 48
16 0 0 ][ 00 0 0 ][ 08 88 45
17 0 0 ][ 01 0 0 ][ 09 59 32
If you have multiple interfaces, use -i parameter to view the hourly network traffic of a specific card like below.
$ vnstat -h -i enp0s8
Suggested read:
Viewing Daily Bandwidth Usage
Use '-d' flag to display the Network traffic of the default network interface per day.
$ vnstat -d
Sample output:
enp0s3 / daily
day rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
09/09/2019 258 KiB | 138 KiB | 396 KiB | 0.09 kbit/s
------------------------+-------------+-------------+---------------
estimated -- | -- | -- |Viewing weekly Bandwidth Usage
$ vnstat -w
Sample output:
enp0s3 / weekly
rx | tx | total | avg. rate
---------------------------+-------------+-------------+---------------
last 7 days 258 KiB | 138 KiB | 396 KiB | 0.00 kbit/s
current week 258 KiB | 138 KiB | 396 KiB | 0.09 kbit/s
---------------------------+-------------+-------------+---------------
estimated -- | -- | -- |Viewing Monthly Bandwidth Usage
To view the monthly usage of a network interface card, use '-m' switch.
$ vnstat -m
Sample output:
enp0s3 / monthly
month rx | tx | total | avg. rate
------------------------+-------------+-------------+---------------
Sep '19 258 KiB | 138 KiB | 396 KiB | 0.00 kbit/s
------------------------+-------------+-------------+---------------
estimated -- | -- | -- |Displaying Bandwidth Usage of Past Top Ten Days
To display the network usage of past ten days, use '-t' flag.
$ vnstat -t
Sample output:
enp0s3 / top 10
# day rx | tx | total | avg. rate
-----------------------------+-------------+-------------+---------------
no data available
-----------------------------+-------------+-------------+---------------It doesn't display any data of top ten days, because I installed Vnstat today.
Suggested read:
Viewing Bandwidth Usage of Particular Time
We can also view the bandwidth usage of particular time.
To display the bandwidth usage of past ten seconds, run:
$ vnstat -i enp0s3 -tr 10
Sample output:
7 packets sampled in 10 seconds
Traffic average for enp0s3
rx 0.28 kbit/s 0 packets/s
tx 0.14 kbit/s 0 packets/sViewing Live Bandwidth Usage
To start live monitoring usage of a particular interface card, run:
$ vnstat -i enp0s3 -l
Sample output:
Monitoring enp0s3... (press CTRL-C to stop) rx: 0 kbit/s 0 p/s tx: 0 kbit/s 0 p/s
To stop live monitoring, press CTRL-C.
For more details, refer man pages:
$ man vnstat
Conclusion
VnStat is handy and useful tool to monitor either your Internet usage or Network traffic for a single or multiple network interfaces. In case, you're wondering how much bandwidth you're consuming daily/monthly, you can use this tool to find out without the help of your Internet service provider or using any third party tools.
Resource:
