iftop is an open source utility that displays bandwidth usage on an interface by host. iftop does for network usage what top does for processor usage. This utility listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts.
iftop listens to network traffic on a named interface, or on the first interface it can find which looks like an external interface if none is specified, and displays a table of current bandwidth usage by pairs of hosts. iftop must be run with sufficient permissions to monitor all network traffic on the interface.
By default, iftop counts all IP packets that pass through the filter, and the direction of the packet is determined according to the direction the packet is moving across the interface.
When running, iftop uses the whole screen to display network usage. At the top of the display is a logarithmic scale for the bar graph which gives a visual indication of traffic.
Features include:
- View bandwidth usage distinguished by source-ip source-port destination-ip destination port.
- Filters.
- Linear bar graphs.
- Support for 802.1q VLANs.
- Support for “tun” interfaces.
- Supports both IPv4 and IPv6.
- Optional removal of the shell escape function.
- Optional fixed bandwidth limits.
- Monitor and display only specific host interface, host source, IP address, IP network block, destination host, bandwidth exceed limit, filter rules, bandwidth rate, bandwidth usage summary, sorting order.
- Option to run iftop in promiscuous mode, so that traffic which does not pass directly through the specified interface is also counted.
- Disable DNS lookups – resolving IPs can reduce performance of the tool and artifically change the traffic statistics.
- Show port data.
- Configuration file support.
Website: www.ex-parrot.com/pdw/iftop
Support: Mailing List
Developer: Paul Warren, Chris Lightfoot
License: GNU General Public License v2.0
iftop is written in C. Learn C with our recommended free books and free tutorials.
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How does the bar graph work at the top? it bounces all over the place from KB to GB and doesn’t seem to compare with total bandwidth usage.
In fact nload, nethogs, iptraf all suck. Is there no single tool that can just tell us current total network utilization on all interfaces and utilization over a period of time.