One both machines run:
[bash]
sudo apt-get install iperf
[/bash]

Then on Computer A:
[bash]
iperf -s
[/bash]

And on Computer B:
[bash]
iperf -c <address of Computer A>
[/bash]
On the client machine, you’ll see something like this:
[bash]
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
[/bash]

参考: How do you test the network speed betwen two boxes?