Command line: how to get instantaneous bandwidth on a port

bandwidthbashcommand linenetworking

I'm trying to get the instantaneous bandwidth usage of eth0, port 10001. I've looked into using lots of different tools, but most of these seem to have an ncurses type output which isn't suitable for piping into my program.

I've seen How can I get an interface's bandwidth at any given second from the Linux command line?, but this only gives the total statistics over an interface and isn't broken down by port.

Ideally, I'd like a command that takes two arguments (eth0 and port 10001), runs for 500ms, calculates the number and size of packets and outputs a simple megabytes/second metric.

Is this too much to ask?

Anyone got any ideas?

Best Answer

You could try to use the ifstat command. With default invocation, it shows bandwidth usage periodically until you hit Control-C But you can invoke it like this:

ifstat <delay> <count>  (i.e. ifstat 1 1)

So that it will give you the bandwidth usage in one second and it's scriptable.

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Linux – What’s the easiest way to sniff TCP traffic data on Linux

Update:

As pointed by Michal in the comments: From tcpflow version 1.3 the -e option is used for specifying the scanner name. So the error "Invalid scanner name '8983'" is printed. The correct command is

sudo tcpflow -i any -C -J port 1234

(also -J has been changed to -g in the latest release)

Thanks to yves for pointing me to "tcpflow". Here's the commmand-line:

tcpflow -i any -C -e port 1234  # as root, or with sudo

This does everything I want

displays the data byte-for-byte as it comes in
doesn't display any other metadata
listens on all interfaces (so it captures data coming from within the machine and outside)

The "-C" tells it to dump to the console instead of a file. The "-e" enables colors so client->server and server->client are visually distinct.

I installed tcpflow by simply doing

sudo apt-get install tcpflow

Linux – How to get an interface’s bandwidth at any given second from the Linux command line

The number of bytes sent and received by eth0 since the interface was brought up can be read in /sys/class/net/eth0/statistics/tx_bytes and /sys/class/net/eth0/statistics/rx_bytes respectively. The number of packets can be read in …/tx_packets and …/rx_packets. If you have an older kernel that doesn't provide these files, the data is available in the output of /sbin/ifconfig eth0.

Best Answer

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Linux – What’s the easiest way to sniff TCP traffic data on Linux

Linux – How to get an interface’s bandwidth at any given second from the Linux command line

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