TCP sockets in your shell

Vide Debian, Linux, Oneliner, Tips

Usually I always used netcat to send TCP data but there’s another way, builtin in bash. You can send the string “Hello world” to 192.168.1.1 on port 15123 using:

echo "Hello world" > /dev/tcp/192.168.1.1/15123

Simple, quick and effective :)

Note: thanks to Waldner for pointing out that it’s built-in in bash and there’s no need for an “mknode”

3 thoughts on “TCP sockets in your shell”

  1. Let’s see if now I’m not caught by HTML formatting…

    You don’t need the special /dev/tcp file. “/dev/tcp” is actually a special device name that is intercepted and parsed directly by bash.

    See for example:

    $ ls /dev/tcp
ls: /dev/tcp: No such file or directory
$ exec 3<>/dev/tcp/www.google.com/80
$ echo "GET /" >&3
$ cat <&3
HTTP/1.0 302 Found
Location: http://www.google.co.uk/
Cache-Control: private
Content-Type: text/html; charset=UTF-8
Set-Cookie: PREF=ID=cd7f743bb28bd67b:FF=0:TM=1297681936:LM=1297681936:S=uohjEzE2DoJtkq92; expires=Wed, 13-Feb-2013 11:12:16 GMT; path=/; domain=.google.com
Set-Cookie: NID=44=s4FRgfes_aI9GwDbRkLriVRsc8jQC74yL5YUB_p6wwNGZvdAFQUL90lENKQZ5iLcgoNkUwF7Ew_s234gYLWR9gGTvw7SrZioGrTvIJ5ldHrcWYf0snw3Hb4S-mhP6yFT; expires=Tue, 16-Aug-2011 11:12:16 GMT; path=/; domain=.google.com; HttpOnly
Date: Mon, 14 Feb 2011 11:12:16 GMT
Server: gws
Content-Length: 221
X-XSS-Protection: 1; mode=block

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>302 Moved</TITLE></HEAD><BODY>
<H1>302 Moved</H1>
The document has moved
<A HREF="http://www.google.co.uk/">here</A>.
</BODY></HTML>
$ exec 3>&-
$
    Reply

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