A Unix Utility You Should Know About: Netcat (2009)

#1

Post by shawndumas » Mon, Aug 05, 2013, 3:26 AM UTC

A Unix Utility You Should Know About: Netcat (2009)
catonmat.net

Re: A Unix Utility You Should Know About: Netcat (2009)

#2

Post by voltagex_ » Mon, Aug 05, 2013, 3:32 AM UTC

There are so many different variants of netcat:

nc, netcat, ncat, socat... I can never be sure of which syntax I'm going to get on an unfamiliar server.

Re: A Unix Utility You Should Know About: Netcat (2009)

#3

Post by sargun » Mon, Aug 05, 2013, 3:35 AM UTC

There is a better utility available for folks. Ncat - part of famous the Nmap (5) project. It has more features than netcat that people might find useful - like SCTP, SOCKS, etc..

You can find out more about it: http://nmap.org/ncat/

Re: A Unix Utility You Should Know About: Netcat (2009)

#4

Post by sehrope » Mon, Aug 05, 2013, 3:39 AM UTC

Netcat is indeed very versatile and useful but most of the time it's used improperly when used as a server (-l mode). Unless you're doing basic network diagnostics (ex: testing if firewall ports are open) you're better off using openssl (s_server mode) or more likely good ol' SSH port forwarding.

Re: A Unix Utility You Should Know About: Netcat (2009)

#5

Post by ams6110 » Mon, Aug 05, 2013, 3:45 AM UTC

You should also know about the so-called "netcat mode" in OpenSSH:

   -W host:port
       Requests that standard input and output on the client be
       forwarded to host on port over the secure channel.  Implies -N,
       -T, ExitOnForwardFailure and ClearAllForwardings.  Works with
       Protocol version 2 only.

Re: A Unix Utility You Should Know About: Netcat (2009)

#6

Post by diminoten » Mon, Aug 05, 2013, 4:23 AM UTC

sargun wrote: post #3

There is a better utility available for folks. Ncat - part of famous the Nmap (5) project. It has more features than netcat that people might find useful - like SCTP, SOCKS, etc.. You can find out more about it: http://nmap.org/ncat/

Ncat is also more compassionate regarding command line parameters.

Depending on the nc app you have installed on your machine, params will have to be passed using different flags or in differing orders (someone should post why there are different kinds of netcat, I forget). Ncat accepts either format, and sends you cards on your birthday.

Re: A Unix Utility You Should Know About: Netcat (2009)

#7

Post by tzury » Mon, Aug 05, 2013, 4:24 AM UTC

Some more examples at wikipedia

http://en.wikipedia.org/wiki/Netcat#Examples

Re: A Unix Utility You Should Know About: Netcat (2009)

#8

Post by LukeShu » Mon, Aug 05, 2013, 4:33 AM UTC

voltagex_ wrote: post #2

There are so many different variants of netcat: nc, netcat, ncat, socat... I can never be sure of which syntax I'm going to get on an unfamiliar server.

nc, ncat, and netcat are all the "same". Any of them could be any of:

  * the original netcat (http://nc110.sourceforge.net/)
  * OpenBSD netcat
  * "GNU netcat" (not affiliated with GNU)
  * BusyBox netcat
  * Nmap ncat (well, this one is typically always "ncat")

They all take roughly the same, but different, syntax, like 'cp', 'ls', or any of the *nix utilities with multiple implementations.

Re: A Unix Utility You Should Know About: Netcat (2009)

#9

Post by platz » Mon, Aug 05, 2013, 4:48 AM UTC

I'm under the impression that socat is the most versatile, but probably involves more typing for similar commands.

Re: A Unix Utility You Should Know About: Netcat (2009)

#10

Post by jvoorhis » Mon, Aug 05, 2013, 4:52 AM UTC

Stupid LAN trick: you can combine nc with pbcopy/pbpaste for distributed copy/paste on macs.