Essential Linux Command‑Line Tools for Network Monitoring

nethogs

Displays per‑process bandwidth usage for IPv4 and IPv6. Run on a specific interface (e.g., eth0) to see upload and download rates per PID. nethogs eth0 Use -p to enable promiscuous mode if required.

nethogs -p wlan0

nload

Console visualizer that shows real‑time inbound and outbound traffic graphs for a selected interface. Switch interfaces with the left/right arrow keys.

nload

slurm

ASCII‑based bandwidth monitor with interactive keys (c, s, r, L, m, q). Install from the distribution repository.

sudo apt-get install slurm

sudo yum -y install slurm

iftop

Shows bandwidth usage per socket pair. Install and run on a chosen interface.

sudo apt-get install iftop

sudo yum -y install iftop

sudo iftop -i wlan0

collectl

Collects system performance data, including network statistics. It supports a recording mode (writes data to files or sockets) and a replay mode (reads recorded files).

sudo apt-get install collectl

sudo yum -y install collectl

netstat (net‑tools)

Displays TCP/UDP connections, routing tables, interface statistics, and protocol counters.

sudo apt-get install net-tools

sudo yum -y install net-tools

netstat -tulnp

netload (netdiag)

Provides a brief report of total bytes transferred since the program started. Part of the netdiag package.

sudo apt-get install netdiag

sudo yum -y install netdiag

netload wlan0

Nagios

Open‑source monitoring system with a web interface (e.g., http://localhost/nagios/) for tracking servers, switches, routers, and printers. Installation follows the standard Nagios documentation.

EtherApe

Graphical network monitor that visualizes traffic by host and protocol. Supports Ethernet, FDDI, token‑ring, ISDN, PPP, SLIP, and WLAN interfaces.

sudo apt-get install etherape

sudo yum -y install etherape

sudo etherape

tcpflow

Captures TCP streams and saves each flow to a separate file for later analysis. Installable from distribution repositories or via the Repoforge RPM.

sudo apt-get install tcpflow

sudo yum -y install tcpflow

# yum install --nogpgcheck http://pkgs.repoforge.org/tcpflow/tcpflow-0.21-1.2.el6.rf.x86_64.rpm

sudo tcpflow -i eth0 port 8000

IPTraf

Console‑based network statistics tool that shows packet/byte counts, interface info, and TCP/UDP traffic.

sudo apt-get install iptraf

sudo yum -y install iptraf

sudo iptraf wlan0

Speedometer

Simple visualizer that draws a graph of upload and download rates for a given interface.

sudo apt-get install speedometer

sudo yum -y install speedometer

speedometer -r wlan0 -t wlan0

Netwatch (netdiag)

Shows current connections and transfer rates for local and remote hosts. Part of the netdiag suite.

sudo apt-get install netdiag

sudo yum -y install netwatch

sudo netwatch -e wlan0 -nt

Trafshow

Reports active connections, protocols, and transfer rates with pcap‑style filtering.

sudo apt-get install trafshow

sudo yum -y install trafshow

sudo trafshow -i wlan0

sudo trafshow -i wlan0 tcp

vnstat

Daemon‑based traffic logger that records total transferred data and can produce historical usage reports. Use -l for live monitoring.

sudo apt-get install vnstat

sudo yum -y install vnstat

vnstat

vnstat -l

tcptrack

Displays live TCP connection status similar to top. Can filter by port.

sudo apt-get install tcptrack

# yum -y install tcptrack

sudo tcptrack -i wlan0

tcptrack -i wlan0 port 80

CBM (Color Bandwidth Meter)

Shows bandwidth usage for all network devices. Source code is available at http://www.isotton.com/utils/cbm/.

sudo apt-get install cbm

cbm

bmon

Bandwidth monitor with curses, HTML, and ASCII output modes.

sudo apt-get install bmon

sudo yum -y install bmon

bmon

tcpdump

Powerful packet capture tool for debugging and analysis. Capture on a specific interface or filter by port.

sudo apt-get install tcpdump

sudo yum -y install tcpdump

sudo tcpdump -i wlan0

sudo tcpdump -i wlan0 'port 80'

ntopng

Next‑generation version of ntop; provides a web‑based interface for traffic analysis. Requires compilation from source on Debian/Ubuntu.

sudo apt-get install libpcap-dev libglib2.0-dev libgeoip-dev redis-server wget libxml2-dev build-essential checkinstall

wget http://sourceforge.net/projects/ntop/files/ntopng/ntopng-1.1_6932.tgz/download -O ntopng.tgz

tar xzf ntopng.tgz && cd ntopng-1.1_6932

./configure && make && sudo make install

After installation, access the web UI (default http://localhost:3000/).