Ubuntu – How to test the network speed between two boxes

bandwidthnetworkingtesting

I have a gigabit network set up in my house and a few Ubuntu based boxes. Out of complete curiosity I would like to check the speed between the two boxes. I am not having any problems with speed or anything, it really is just the geek in me that is curious. Plus maybe the results will let me know if there is room for improvement, or that I have something configured wrongly.

So how do you properly test the network speed between Ubuntu boxes?

Best Answer

I use iperf. It's a client server arrangement in that you run it in server mode at one end and connect to its from another computer on the other side of the network.

One both machines run:

sudo apt-get install iperf

We'll start an iperf server on one of the machines:

iperf -s

And then on the other computer, tell iperf to connect as a client:

iperf -c <address of other computer>

On the client machine, you'll see something like this:

oli@bert:~$ iperf -c tim
------------------------------------------------------------
Client connecting to tim, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.4 port 37248 connected with 192.168.0.5 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1.04 GBytes    893 Mbits/sec

Of course, if you're running a firewall on the server machine, you'll need to allow connections on port 5001 or change the port with the -p flag.

You can do pretty much the same thing with plain old nc (netcat) if you're that way inclined. On the server machine:

nc -vvlnp 12345 >/dev/null

And the client can pipe a gigabyte of zeros through dd over the nc tunnel.

dd if=/dev/zero bs=1M count=1K | nc -vvn 10.10.0.2 12345

As demod:

$ dd if=/dev/zero bs=1M count=1K | nc -vvn 10.10.0.2 12345
Connection to 10.10.0.2 12345 port [tcp/*] succeeded!
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 9.11995 s, 118 MB/s

The timing there is given by dd but it should be accurate enough as it can only output as fast the pipe will take it. If you're unhappy with that you could wrap the whole thing up in a time call.

Remember that the result is in megabytes so multiply it by 8 to get a megabits-per-second speed. The demo above is running at 944mbps.

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