Linux – How to see sent/received data by netcat

linuxnetcat

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?

Best Answer

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
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