Essential Linux Command‑Line Tools for Monitoring Network Bandwidth

The article presents a set of Linux command‑line tools for monitoring network usage, detailing how each tool measures traffic, what information it displays, and how to install it on common distributions.

nload

nload shows inbound and outbound traffic separately and can draw adjustable charts. It is simple to use with few options, making it suitable for quick total bandwidth checks.

Installation: Available in default repositories of Fedora and Ubuntu; CentOS users can obtain it from the EPEL repository.

iftop

iftop measures data transferred per socket connection using the pcap library to capture packets, summarizing packet sizes and counts. It cannot show process IDs but supports filtering and can suppress DNS lookups with the -n option.

Installation: Available in default repositories of Ubuntu/Debian/Fedora; CentOS users can install from EPEL.

iptraf

iptraf is an interactive, colorful LAN monitoring tool that displays traffic volume for each connection and host.

Installation instructions are provided via screenshots (typically from the distribution’s package manager).

nethogs

nethogs is a lightweight "net top" utility that lists bandwidth usage per process, sorting the most consuming processes at the top and showing PID, user, and command path.

Installation: Available in default repositories of Ubuntu, Debian, and Fedora; CentOS users can obtain it from EPEL.

bmon

bmon (Bandwidth Monitor) displays traffic load for all network interfaces with charts and detailed packet‑level information.

Installation: Installable from default repositories of Ubuntu, Debian, and Fedora; CentOS users need the Repoforge repository.

slurm

slurm provides device statistics and ASCII graphics with three display modes activated by the c, s, and l keys. It offers basic monitoring without detailed per‑connection data.

Installation: Available via default repositories on Ubuntu/Debian/Fedora; CentOS users must use Repoforge.

tcptrack

tcptrack, similar to iftop, captures packets with pcap, calculates per‑connection bandwidth, and supports standard pcap filters.

Installation: Included in default repositories of Ubuntu, Debian, and Fedora; CentOS users can obtain it from RepoForge.

vnstat

vnstat runs a background daemon that continuously records transmitted data, allowing historical reports of daily or monthly bandwidth usage. Running it without options shows total data since the daemon started.

Installation: Packages are available in standard repositories for most distributions; detailed options are documented in the manual page.

bwm-ng

bwm-ng (Bandwidth Monitor Next Generation) is a simple real‑time tool that reports summary information and can display bar graphs in curses mode on sufficiently large consoles.

Installation: Installable from EPEL on CentOS.

cbm (Color Bandwidth Meter)

cbm is a tiny utility that shows real‑time traffic statistics per network interface without additional options.

speedometer

speedometer draws attractive graphs of inbound and outbound traffic for a selected interface.

pktstat

pktstat shows active connections, their transfer speeds, connection types (TCP/UDP), and, for HTTP, detailed request information.

netwatch

netwatch, part of the netdiag suite, displays connections between the local host and remote hosts along with per‑connection traffic speeds.

trafshow

trafshow reports active connections, protocols, and transfer speeds, supporting pcap‑style filters; it can be limited to TCP connections.

netload

netload provides a brief report of current traffic load and total bytes transferred since the program started; it is part of the netdiag suite.

ifstat

ifstat outputs bandwidth statistics in batch mode, suitable for logging and further analysis.

dstat

dstat, written in Python, monitors various system statistics, can output in batch mode, and can write data to CSV files; it can report network bandwidth as shown in the example.

collectl

collectl reports system statistics in a format similar to dstat, covering CPU, memory, and network usage.

Conclusion: These command‑line tools enable quick inspection of network bandwidth on Linux servers via SSH. For web‑based monitoring, tools like ntop, darkstat, or enterprise solutions such as Nagios can be used.