How can I see sent/received data by netcat?

Question

I follow this post to check speed with netcat , but in his blog when he do ctrl-c ,he get data on sent received bytes.

In the post he ran :

time yes|nc -v -v -n 192.168.0.8 2222 >/dev/null
than after ctrl-c het get:
sent 87478272, rcvd 0
real 0m9.993s
user 0m2.075s
sys 0m0.939s

When I do ctrl-c , I don't get this data.

How can I get sent/received data by netcat?

score 8 · Accepted Answer · edited Jun 16 '16 at 18:49

There are actually two implementations of netcat, the original implementation by *Hobbit* (called netcat-traditional in Debian/Ubuntu) and the OpenBSD implementation (called netcat-openbsd in Debian/Ubuntu). In Debian/Ubuntu the binaries are called nc.traditional and nc.openbsd respectively (and nc is a link to one of those via the alternatives system).

The blog post you reference is using nc.traditional which does show the sent/received bytes when exiting. You are probably using nc.openbsd which doesn't. Install the traditional implementation and call it explicitly.

% time yes | nc.traditional -vvn 127.0.0.1 10000 > /dev/null
(UNKNOWN) [127.0.0.1] 10000 (webmin) open
^C sent 99422208, rcvd 0
yes  1,06s user 0,09s system 38% cpu 3,003 total

Alternately, if you prefer to use the nc.openbsd you can pipe the output of netcat on the server side to wc -c and inspect the output like so:

% nc -l -n -p 10000 | wc --bytes
99422208

ewwhite · Answer 2 · 2012-10-25T14:34:34.257

3

You can use the Pipe Viewer (pv) utility to watch the visual progress of a stream. It can be modified to display the units of choice and is available on most distributions.

Example:

cat largefile | pv | netcat 192.168.10.1000 1234

edited Oct 25 '12 at 14:34

answered Oct 25 '12 at 14:20

ewwhite

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I want to get it from netcat like in the posted blog ? – Avihai Marchiano Oct 25 '12 at 14:34
Please show your command string. – ewwhite Oct 25 '12 at 14:36
add this to the question, thank you. You can see it in the blog link. – Avihai Marchiano Oct 25 '12 at 14:39
1

`time yes|nc -v -v -n 192.168.0.8 2222 | pv | >/dev/null` – ewwhite Oct 25 '12 at 14:40
i copy paste the command that you wrote (in the comment), in the server side the pv display rate, but on the client side the pv display rate of 0 – Avihai Marchiano Oct 25 '12 at 16:01
Experiment with it. I was just recommending the tool. You'll have to tailor it to your specific needs. – ewwhite Oct 25 '12 at 16:07
1

The command should be like this - time yes| pv | nc -v -v -n 192.168.0.8 2222 >/dev/null – Avihai Marchiano Oct 25 '12 at 16:37

How can I see sent/received data by netcat?

2 Answers2