Send POST request with netcat

Asked 28/6, 2010 at 19:0 Answered 29/6, 2010 at 4:45

I have found this little script in PHP that send a simple request to twitter for update your status, I have tried this: http://pratham.name/twitter-php-script-without-curl.html, and it work. Now, I want send this request with netcat, but this doesn't work, why?

I send request in this way:

echo -e $head | nc twitter.com 80

The $head are my header that I have tried with also PHP, so it are right.

Anyone know how I can make this? Thanks to all.

edit.

head="POST http://twitter.com/statuses/update.json HTTP/1.1\r\n
Host: twitter.com\r\n
Authorization: Basic myname:passwordinbs64\r\n
Content-type: application/x-www-form-urlencoded\r\n
Content-length: 10\r\n
Connection: Close\r\n\r\n
status=mymessage";

echo -e $head | nc twitter.com 80

Engraft answered 28/6, 2010 at 19:0 Comment(5)

We're not mind-readers. Link the script, and show the contents of $head. – Herson 28/6, 2010 at 19:3

Sorry, I have edited the message. – Engraft 28/6, 2010 at 19:4

Thanks, please also show how you're initializing $head. Also, if you have curl or wget, that will probably be easier. – Herson 28/6, 2010 at 19:11

Sir, I don't want use curl or wget for now. – Engraft 28/6, 2010 at 20:21

I have updated my answer, it now contains the solution – Difficult 29/6, 2010 at 10:26

The data you send is not correct. Here's the command I'm executing:

$ head="POST /statuses/update.json HTTP/1.1\r\n
Host: twitter.com\r\n
Authorization: Basic myname:passwordinbs64\r\n
Content-type: application/x-www-form-urlencoded\r\n
Content-length: 10\r\n
Connection: Close\r\n\r\n
status=mymessage"; echo $head  | nc twitter.com 80

HTTP/1.1 400 Bad Request
Date: Tue, 29 Jun 2010 10:19:38 GMT
Server: Apache
Vary: Accept-Encoding
Content-Length: 226
Connection: close
Content-Type: text/html; charset=iso-8859-1

<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>400 Bad Request</title>
</head><body>
<h1>Bad Request</h1>
<p>Your browser sent a request that this server could not understand.<br />
</p>
</body></html>

I'm running a tcpdump in parallel and here is what it shows me:

0x0020:  5018 ffff 671f 0000 504f 5354 2068 7474  P...g...POST.htt
0x0030:  703a 2f2f 7477 6974 7465 722e 636f 6d2f  p://twitter.com/
0x0040:  7374 6174 7573 6573 2f75 7064 6174 652e  statuses/update.
0x0050:  6a73 6f6e 2048 5454 502f 312e 310d 0a20  json.HTTP/1.1...
0x0060:  486f 7374 3a20 7477 6974 7465 722e 636f  Host:.twitter.co
0x0070:  6d0d 0a20 4175 7468 6f72 697a 6174 696f  m...Authorizatio
0x0080:  6e3a 2042 6173 6963 206d 796e 616d 653a  n:.Basic.myname:
0x0090:  7061 7373 776f 7264 696e 6273 3634 0d0a  passwordinbs64..
0x00a0:  2043 6f6e 7465 6e74 2d74 7970 653a 2061  .Content-type:.a
0x00b0:  7070 6c69 6361 7469 6f6e 2f78 2d77 7777  pplication/x-www
0x00c0:  2d66 6f72 6d2d 7572 6c65 6e63 6f64 6564  -form-urlencoded
0x00d0:  0d0a 2043 6f6e 7465 6e74 2d6c 656e 6774  ...Content-lengt
0x00e0:  683a 2031 300d 0a20 436f 6e6e 6563 7469  h:.10...Connecti
0x00f0:  6f6e 3a20 436c 6f73 650d 0a0d 0a20 7374  on:.Close.....st
0x0100:  6174 7573 3d6d 796d 6573 7361 6765 0a    atus=mymessage.

Do you see the mistake? At each line break are three characters, but there should be only two. This happens because you have a real line break in your variable definition that becomes a space in the shell. E.g.

$ head="line1
line2" ; echo $head

line1 line2

Try writing it all in one line instead.

$ head="POST /statuses/update.json HTTP/1.1\r\nHost: twitter.com\r\nAuthorization: Basic myname:passwordinbs64\r\nContent-type: application/x-www-form-urlencoded\r\nContent-length: 10\r\nConnection: Close\r\n\r\nstatus=mymessage" ; echo $head | nc twitter.com 80

HTTP/1.1 401 Unauthorized
Date: Tue, 29 Jun 2010 10:25:43 GMT
Server: hi
Status: 401 Unauthorized
X-Runtime: 0.00577
Content-Type: application/json; charset=utf-8
Content-Length: 63
Cache-Control: no-cache, max-age=300
Set-Cookie: k=194.145.236.196.1277807143945525; path=/; expires=Tue, 06-Jul-10 10:25:43 GMT; domain=.twitter.com
Set-Cookie: guest_id=1277807143950191; path=/; expires=Thu, 29 Jul 2010 10:25:43 GMT
Set-Cookie: _twitter_sess=BAh7CDoPY3JlYXRlZF9hdGwrCBOsPYMpAToHaWQiJWQzZDkxNTg2MTY3OTFk%250AMzg5OTUyNWFhZGZlZDY0YjJmIgpmbGFzaElDOidBY3Rpb25Db250cm9sbGVy%250AOjpGbGFzaDo6Rmxhc2hIYXNoewAGOgpAdXNlZHsA--e95d14c755b85ff19606a0bc907c8b7a63d1b508; domain=.twitter.com; path=/
Expires: Tue, 29 Jun 2010 10:30:43 GMT
Vary: Accept-Encoding
Connection: close

{"errors":[{"code":32,"message":"Could not authenticate you"}]}

Difficult answered 28/6, 2010 at 19:10 Comment(6)

Usually when you send HTTP requests, the first line contain only URI not full URL, it's probably in the spec, but I didn't check it to confirm, so it should be head="POST /statuses/update.json HTTP/1.1\r\n – Aiglet 13/11, 2018 at 10:49

@Aiglet Makes actually sense, as http:// would be redundant, as when performing a HTTP POST, of course you are using the HTTP protocol. Just like it is clear to which server you are talking to as you are talking to it right now and for distinguish of different domain, there's the HOST header field. So thanks, I will update my answer accordingly. Yet the issue of the initial user was really duplicate line breaks, though. – Difficult 13/11, 2018 at 11:39

@αғsнιη If you quote it, it's still incorrect, as then it will be \r\n\n at the end of every line. Quoting only prevents the \n to become a space. – Difficult 25/10, 2022 at 9:13

ahh, that's because I forgot to add -e switch to the echo in my edit. – Handshaker 25/10, 2022 at 9:28

@αғsнιη -e, which BTW is not part of the POSIX standard (so shells other than Bash may not support it for a built-in echo and the system's /bin/echo may not support it either) only makes Bash itself interpret the backslash escapes, it will not strip the extra line break, so you are still having twice a newline character at the end. See tpcg.io/_S5STRY In the second case, you still have twice 0a between both lines. – Difficult 25/10, 2022 at 9:48

right, BTW question is tagged with bash not POSIX, so it should be fine. and about trailing newline there is -n switch too. – Handshaker 25/10, 2022 at 11:24

If you don't put quotes around "$head" then your formatting won't be as you (or Twitter) expect it. Also, since your variable contains newlines/carriage returns, it will probably help to suppress echo from supplying its own.

echo -ne "$head" | nc twitter.com 80

Hankins answered 29/6, 2010 at 4:45 Comment(0)

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