nload Command

Introduction

nload is a console-based network monitoring utility that displays the current network traffic usage in real time. Unlike more complex tools that break down traffic by connection or process, nload focuses on providing a simple, clear visualization of the total incoming and outgoing bandwidth on network interfaces.

The tool presents network traffic using easy-to-read graphs and provides additional statistics such as total transferred data, min/max/average bandwidth usage, and more. This makes nload particularly useful for quickly assessing network performance and identifying bandwidth issues without the complexity of more detailed analysis tools.

nload is designed with simplicity in mind, making it ideal for:

• System administrators who need to quickly check network utilization
• Users troubleshooting network performance issues
• Server monitoring in environments where graphical tools aren't available
• Quick verification of bandwidth usage during network operations

Installation

nload is available in the standard repositories of most Linux distributions.

Debian/Ubuntu-based Systems

sudo apt update
sudo apt install nload

Red Hat/CentOS/Fedora Systems

# For CentOS/RHEL with EPEL repository enabled
sudo yum install epel-release
sudo yum install nload
 
# For Fedora
sudo dnf install nload

Arch Linux

sudo pacman -S nload

From Source

If nload is not available in your distribution's repositories, you can compile it from source:

# Install dependencies
sudo apt install build-essential ncurses-dev
 
# Download source
wget http://www.roland-riegel.de/nload/nload-0.7.4.tar.gz
 
# Extract and compile
tar -xzf nload-0.7.4.tar.gz
cd nload-0.7.4
./configure
make
sudo make install

Basic Usage

To start nload with default settings, simply run:

nload

Unlike some other network monitoring tools, nload doesn't require root privileges for basic functionality.

Monitoring Specific Interfaces

By default, nload displays the first available network interface. To specify a particular interface:

nload eth0  # Monitor the eth0 interface

To monitor multiple interfaces, you can specify them as additional arguments:

nload eth0 wlan0  # Monitor both eth0 and wlan0

When monitoring multiple interfaces, you can switch between them using the left and right arrow keys.

Understanding the Display

The nload display consists of two main sections for each network interface:

Incoming Traffic (Top Section)

• Graph: Visual representation of incoming bandwidth usage over time
• Current: Current incoming bandwidth
• Average: Average incoming bandwidth since nload started
• Min/Max: Minimum and maximum incoming bandwidth observed
• Total: Total amount of data received since nload started

Outgoing Traffic (Bottom Section)

• Graph: Visual representation of outgoing bandwidth usage over time
• Current: Current outgoing bandwidth
• Average: Average outgoing bandwidth since nload started
• Min/Max: Minimum and maximum outgoing bandwidth observed
• Total: Total amount of data sent since nload started

Status Bar

At the bottom of the screen, nload displays:

• The currently displayed device
• Total number of devices being monitored
• Navigation hints

Command-Line Options

nload offers several command-line options to customize its behavior:

Display Options

# Set the refresh interval to 500 milliseconds (default is 500)
nload -t 500
 
# Set the number of data points in the traffic graphs to 20 (default is 60)
nload -a 20
 
# Set the scaling factor for the traffic graphs (default is 0)
nload -i 10
 
# Set the maximum bandwidth for the traffic graphs (in Kbit/s)
nload -m 10000
 
# Show multiple interfaces in multiple windows
nload -m devices

Unit Options

# Display traffic in bits per second (default)
nload -u b
 
# Display traffic in bytes per second
nload -u B
 
# Display traffic in kilobits per second
nload -u k
 
# Display traffic in kilobytes per second
nload -u K
 
# Display traffic in megabits per second
nload -u m
 
# Display traffic in megabytes per second
nload -u M
 
# Display traffic in gigabits per second
nload -u g
 
# Display traffic in gigabytes per second
nload -u G

Output Format

# Set the number of digits after the decimal point (default is 2)
nload -o 1

Interactive Commands

While nload is running, you can use various keyboard commands to control the display:

Navigation

• Left Arrow or h: Switch to the previous network device
• Right Arrow or l: Switch to the next network device
• F5 or r: Refresh the display immediately
• F6: Cycle through the available units (bit/s, byte/s, etc.)
• q: Quit nload

Display Settings

• F2: Decrease the refresh interval
• F3: Increase the refresh interval
• F4: Change the number of data points in the traffic graphs

Practical Examples

Basic Monitoring

To monitor the default network interface:

nload

Monitoring Multiple Interfaces

To monitor both wired and wireless interfaces:

nload eth0 wlan0

Custom Refresh Rate

For more responsive updates (200ms refresh):

nload -t 200

Fixed Scale Graph

To set a fixed maximum scale for the graph (useful for consistent visualization):

nload -m 100000  # Set max scale to 100 Mbit/s

Bytes Instead of Bits

To display traffic in bytes per second instead of bits:

nload -u B

Combining Options

You can combine multiple options for customized monitoring:

nload -t 100 -a 100 -m 10000 -u M eth0

This sets a 100ms refresh rate, 100 data points in the graph, a maximum scale of 10,000 Kbit/s, and displays traffic in megabytes per second for the eth0 interface.

Advanced Usage

Using nload in Scripts

While nload is primarily an interactive tool, you can use it in non-interactive mode to get a snapshot of current network usage:

nload -n eth0

This will display a single update and exit, which can be useful for scripting.

Continuous Monitoring with Logging

To log network usage over time, you can combine nload with other tools:

# Log network usage every 5 seconds
while true; do nload eth0 -n | grep "Curr" >> network_log.txt; sleep 5; done

Monitoring Remote Systems

You can use nload over SSH to monitor remote systems:

ssh user@remote_server 'nload'

Troubleshooting

Common Issues

"Device not found"

This occurs when specifying a non-existent interface:

Solution: Use 'ip a' to list available interfaces, then use the correct interface name

Low Resolution Graphs

If the graphs appear too compressed or lack detail:

Solution: Increase the number of data points with -a option

Inaccurate Readings

If readings seem inaccurate or inconsistent:

Solution: Ensure no other bandwidth-intensive processes are running in the background

Comparison with Similar Tools

nload vs. iftop

• nload: Shows total bandwidth usage on interfaces with graphs
• iftop: Shows bandwidth usage broken down by connection

nload vs. bmon

• nload: Simpler interface focused on bandwidth graphs
• bmon: More detailed statistics and can monitor multiple interfaces simultaneously in one view

nload vs. nethogs

• nload: Shows bandwidth usage by interface
• nethogs: Shows bandwidth usage by process

nload vs. vnstat

• nload: Real-time monitoring with no persistent data
• vnstat: Collects and stores historical network usage data

Best Practices

Efficient Monitoring

1. Adjust refresh rate appropriately: Lower refresh rates provide more detail but consume more CPU
2. Monitor specific interfaces: Only monitor the interfaces relevant to your investigation
3. Set appropriate scales: Use the -m option to set a fixed scale for consistent visualization

Performance Considerations

1. CPU usage: nload is generally lightweight, but very low refresh intervals can increase CPU usage
2. Terminal performance: Large graphs in small terminals may not display correctly
3. Remote monitoring: When monitoring over SSH, consider network latency effects on refresh rates

Conclusion

nload is a simple yet powerful tool for monitoring network traffic in real-time. Its straightforward interface and visual graphs make it ideal for quickly assessing network performance without the complexity of more detailed analysis tools.

Whether you're troubleshooting network issues, monitoring server performance, or just curious about your current bandwidth usage, nload provides an intuitive way to visualize network traffic. Its lightweight nature and console-based interface make it particularly valuable in server environments where graphical tools aren't available or practical.

While it doesn't provide the detailed connection-level or process-level information that some other tools offer, nload's focus on simplicity and clarity makes it an essential part of any system administrator's toolkit for quick network monitoring tasks.