Cfrgtkky

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?

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.

Same as Oli's recommendation for iperf. Just want to add several points:

1. There are also windows clients that enables testing across
   platforms.


2. 
   -t <seconds> changes the test length. -P <n> changes the number of simultaneous connections. For example, iperf -c [target IP] -P 10 -t 30 tests 10 connections together for 30 seconds and gives aggregated results along with 10 separate connection speeds.


3. You don't need sudo. You can simply download the binary at http://iperf.fr/. It should work. Download it with wget, make it executable with chmod, and you can directly run the binary. It works perfectly.

I found that, using default settings, the single connection speed fluctuates quite a bit. However, with 3+ parallel connections, the results are more consistent on my gigabyte switch. (consistently @ 910-920Mbps)

Using this script you can easily test connection speed between your machine and some remote host.
Example of using:

$ scp-speed-test.sh user@remote_host 80000

• 
  user@remote_host is your destination host (you must have ssh-access
  to this host)


• 
  80000 is the approximate size of test file (in kbs), which will be
  received to the remote host. It is not mandatory argument.

If you want to test your Ethernet LAN at a lower level you can use Etherate which is a free Linux CLI Ethernet testing tool:

https://github.com/jwbensley/Etherate

Throwing it in the mix as tools like iPerf (which are very good!) operate over IP and TCP or UDP. Etherate tests directly over Ethernet / OSI layer 2.

There are also some other nice command-line tools for bandwidth benchmarking between two hosts:

nuttcp

server$ nuttcp -S

client$ nuttcp -v -v -i1 1.1.1.1 ;# 1.1.1.1 is server's address

nepim

 server$ nepim

 client$ nepim -d -c 1.1.1.1 ;# 1.1.1.1 is server's address

goben

 server$ goben

 client$ goben -hosts 1.1.1.1 ;# 1.1.1.1 is server's address