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situering van application protocols in praktijkmodel

well known port numbers
SQL-server (1433) rdesktop (3389) mysql (3306) nfs (2049)
samba (137/139/445)
cups (631) jetdirect (9100/9101/9102) lpd (515)
rpc (111)
ftp (20/21) / telnet (23) / ssh (22) / sftp (22) / smtp (25) / pop3 (110) / dns (53) / dhcp (67-68)/ tftp (69)/ ntp (123) https (443)/ imap4 (143)

telnet en netcat als app-protocol tool
https://www.howtoforge.com/useful-uses-of-netcat
+
krumins blog

https://linux801.wordpress.com/2015/06/29/lab-tcp-http/

Spoofing HTTP Headers

You can use netcat to request web pages:

nc ispconfig.org 80

You can then type in headers as follows:

GET / HTTP/1.1
Host: ispconfig.org
Referrer: mypage.com
User-Agent: my-browser

As you see, this allows you to make up your own referrers and browser (User-Agent). After you've typed in your headers, press ENTER twice, and the requested page will appear (including the headers sent back by the remote server):

server2:~# nc exampple.com 80
GET / HTTP/1.1
Host: example.com
Referrer: mypage.com
User-Agent: my-browser

HTTP/1.1 200 OK
Date: Fri, 28 Nov 2008 14:11:49 GMT
Server: Apache/2.2.3 (Debian) mod_ssl/2.2.3 OpenSSL/0.9.8c
Last-Modified: Wed, 26 Nov 2008 19:34:17 GMT
ETag: "228c707-21b1-b6b7e040"
Accept-Ranges: bytes
Content-Length: 8625
Content-Type: text/html

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