Iftop is a
free software
Free software, libre software, libreware sometimes known as freedom-respecting software is computer software distributed open-source license, under terms that allow users to run the software for any purpose as well as to study, change, distribut ...
command-line
system monitor
A system monitor is a hardware or software component used to monitor system resources and performance in a computer system.
Among the management issues regarding use of system monitoring tools are resource usage and privacy. Monitoring can tra ...
tool developed by Paul Warren. It produces a real-time stream of incoming and outgoing network communications from the operating system iftop is running within.
By default, the connections are ordered by
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
usage, with only the largest ("top") bandwidth consumers shown. It is analogous to
top
Top most commonly refers to:
* Top, a basic term of orientation, distinguished from bottom, front, back, and sides
* Spinning top, a ubiquitous traditional toy
* Top (clothing), clothing designed to be worn over the torso
* Mountain top, a moun ...
, but instead of system-wide resource monitoring, it focuses on displaying just network usage. Iftop is typically used for monitoring bandwidth consumption, and while investigating unknown consumers of available network bandwidth.
Description
iftop is a passive monitoring tool. This program monitors network traffic and displays a table of current bandwidth usage, bandwidth measured in bits per second at default, and may be changed to bytes per seconds with the command line option.
An interface may be specified' if not, it will listen on the first interface it finds that appears to be external.
By default, iftop will look up hostnames associated with addresses and counts all IP packets that pass through the filter.
A feature of iftop is that it can suppress display of
DNS
The Domain Name System (DNS) is a hierarchical and distributed name service that provides a naming system for computers, services, and other resources on the Internet or other Internet Protocol (IP) networks. It associates various informatio ...
traffic by using a filter code such as "not port domain", or switch it off entirely, by using the
-n option or by pressing "n" when the program is running. Using the
-F option makes it possible to show packets entering and leaving a given network.
iftop may be used for inspecting TCP or UDP ports also, using the option
-P.
See also
*
Linux/UNIX system performance commands
*
htop
htop is an interactive system monitor process viewer and process manager. It is designed as an alternative to the Unix program top (software), top.
It shows a frequently updated list of the processes running on a computer, normally ordered by t ...
*
netsniff-ng
netsniff-ng is a free Linux network analyzer and networking toolkit originally written by Daniel Borkmann. Its gain of performance is reached by zero-copy mechanisms for network packets (RX_RING, TX_RING), so that the Linux kernel does not need ...
's ifpps top-like statistics tool
*
ntop
*
MTR (software)
My traceroute, originally named Matt's traceroute (MTR), is a computer program that combines the functions of the traceroute and ping programs in one network diagnostic tool.
MTR probes routers on the route path by limiting the number of hops ...
*
List of Unix commands
This is a list of the shell commands of the most recent version of the Portable Operating System Interface (POSIX) IEEE Std 1003.1-2024 which is part of the Single UNIX Specification (SUS). These commands are implemented in many shells on moder ...
References
External links
*
{{unix commands
Unix network-related software
System administration