Top Linux CLI Tools for Real‑Time Network Bandwidth Monitoring

The article introduces several Linux command‑line tools for monitoring network usage, capable of displaying inbound and outbound traffic, measuring current transfer speeds, and, in some cases, showing bandwidth per process.

Overall bandwidth monitoring tools

nload, bmon, slurm, bwm-ng, cbm, speedometer, netload

vnstat, ifstat, dstat, collectl (batch‑style output)

iftop, iptraf, tcptrack, pktstat, netwatch, trafshow (per‑socket bandwidth)

nethogs (per‑process bandwidth)

1. nload

nload separates inbound and outbound traffic, draws simple charts, and offers adjustable scaling. It is useful for a quick overview of total bandwidth without detailed per‑process data.

Installation: available in default repositories of Fedora and Ubuntu; CentOS users need the EPEL repository.

2. iftop

iftop measures data transferred per socket connection using the pcap library, summarizing packet sizes to estimate bandwidth. It cannot show the process ID for each connection but supports filtering and host‑specific monitoring.

Installation: available in default repositories of Ubuntu/Debian/Fedora; CentOS users obtain it from EPEL.

3. iptraf

iptraf is an interactive, colorful LAN monitoring tool that displays each connection and the amount of data transferred between hosts.

Installation: install from the default repository of your distribution.

4. nethogs

nethogs acts as a "net top" utility, listing processes by bandwidth usage, showing PID, user, and command path, which helps quickly identify bandwidth‑hogs.

Installation: available in the default repositories of Ubuntu, Debian, and Fedora; CentOS users need EPEL.

5. bmon

bmon (Bandwidth Monitor) displays traffic load for all network interfaces, providing charts and packet‑level details.

Installation: install from default repositories on Ubuntu/Debian/Fedora; on CentOS install via Repoforge.

6. slurm

slurm shows device statistics with ASCII graphics, offering three visual modes activated by the c, s, and l keys. It provides only basic load information.

Installation: install from the default repository of your distribution.

7. tcptrack

tcptrack, similar to iftop, captures packets via pcap, reports bandwidth per connection, and supports standard pcap filters.

Installation: available in Ubuntu/Debian/Fedora repositories; CentOS users obtain it from RepoForge.

8. vnstat

vnstat runs as a background daemon, continuously recording transferred data and generating historical usage reports. Running without options shows total data since the daemon started; the -l option enables real‑time mode.

Installation: install from the default repository of your distribution.

9. bwm-ng

bwm-ng (Bandwidth Monitor Next Generation) provides a simple real‑time summary of traffic speeds for all interfaces, with an optional curses‑based bar graph.

Installation: install via EPEL on CentOS.

10. cbm (Color Bandwidth Meter)

cbm is a tiny tool that continuously displays traffic size per interface without additional options.

11. speedometer

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

12. pktstat

pktstat shows active connections, their protocols, and transfer speeds, and can display HTTP request details when applicable.

13. netwatch

netwatch (part of the netdiag suite) lists local and remote connections with their data transfer rates.

14. trafshow

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

15. netload

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

16. ifstat

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

17. dstat

dstat, a Python‑based versatile tool, can report various system statistics, including network bandwidth, in CSV or other formats.

18. collectl

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

Conclusion: These command‑line utilities allow 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.