Monitoring bandwidth and traffic

Bandwidth and Traffic Monitoring on Debian Servers

Monitoring bandwidth and network traffic is essential for both dedicated servers and virtual private servers (VPS) to maintain performance, detect abuse, and track usage trends. Debian-based Linux distributions support a wide variety of tools for this purpose, including command-line utilities and web-based dashboards.

Prerequisites

Before using bandwidth monitoring tools, ensure that the system is up to date and essential packages are installed. Root or sudo access is required.

<syntaxhighlight lang="bash"> sudo apt update && sudo apt install wget curl tar unzip -y </syntaxhighlight>

Tools Overview

Tool	Interface Type	Features	Suitable For
vnStat	Command-line	Lightweight bandwidth logging by day/month	General monitoring
iftop	Command-line (real-time)	Real-time traffic by connection/IP	Live traffic observation
nload	Command-line (graphical)	Real-time graphical network usage	Visual terminal output
bmon	Command-line (graphical)	Graphs for all interfaces	Network debugging
Netdata	Web-based dashboard	Full system and bandwidth monitoring	Beginner-friendly GUI

vnStat

vnStat is a lightweight tool that logs bandwidth usage over time.

<syntaxhighlight lang="bash"> sudo apt install vnstat -y sudo vnstat -u -i eth0 sudo systemctl enable vnstat sudo systemctl start vnstat </syntaxhighlight>

View usage:

<syntaxhighlight lang="bash"> vnstat # Summary vnstat -d # Daily vnstat -m # Monthly vnstat -l # Live traffic </syntaxhighlight>

iftop

iftop displays real-time bandwidth usage by IP and port.

<syntaxhighlight lang="bash"> sudo apt install iftop -y sudo iftop -i eth0 </syntaxhighlight>

Controls: Use arrow keys and keys such as T, P, and S to toggle views. Press Ctrl+C to exit.

nload

nload offers a simple terminal-based graphical view of incoming and outgoing traffic.

<syntaxhighlight lang="bash"> sudo apt install nload -y nload </syntaxhighlight>

bmon

bmon (Bandwidth Monitor) provides graphical interface per network device.

<syntaxhighlight lang="bash"> sudo apt install bmon -y bmon </syntaxhighlight>

Netdata

Netdata is a web-based real-time system and bandwidth monitoring tool.

<syntaxhighlight lang="bash"> bash <(curl -Ss https://my-netdata.io/kickstart.sh) </syntaxhighlight>

Once installed, access via browser:

<syntaxhighlight lang="text"> http://your_server_ip:19999 </syntaxhighlight>

Enable and start:

<syntaxhighlight lang="bash"> sudo systemctl enable netdata sudo systemctl start netdata </syntaxhighlight>

Detecting Network Interfaces

To find the primary network interface:

<syntaxhighlight lang="bash"> ip -brief link show </syntaxhighlight>

Typical interface names:

• For VPS: eth0, ens3, venet0
• For dedicated servers: eno1, ens18

Monitoring Per-User Traffic

To view traffic per user or process, install nethogs:

<syntaxhighlight lang="bash"> sudo apt install nethogs -y sudo nethogs eth0 </syntaxhighlight>

Daily Email Report (vnStat)

To receive daily bandwidth reports via email:

1. Install mailutils (if not already installed): <syntaxhighlight lang="bash"> sudo apt install mailutils -y </syntaxhighlight>

2. Add cron job: <syntaxhighlight lang="bash"> sudo crontab -e </syntaxhighlight>

Add the following line:

<syntaxhighlight lang="bash"> 0 1 * * * vnstat -d | mail -s "Daily Bandwidth Report" user@example.com </syntaxhighlight>

Uninstalling Tools

To remove any tool:

<syntaxhighlight lang="bash"> sudo apt remove toolname -y </syntaxhighlight>

Example:

<syntaxhighlight lang="bash"> sudo apt remove vnstat -y </syntaxhighlight>

Summary Table

Tool	Command	Interface Setup	Function
vnStat	vnstat	vnstat -u -i eth0	Usage logging
iftop	iftop -i eth0	Manual	Real-time traffic view
nload	nload	Automatic	Graphical bandwidth monitor
bmon	bmon	Automatic	Graphical per-device stats
Netdata	Browser access	Automatic	Full system & bandwidth monitor
nethogs	nethogs eth0	Automatic	Traffic by user/process