Connect to Mysql

Show Databases

Use a Database

Show tables in a Database

Show table structure

PROCESSES

Show Processlist

Kill process

list dirs sorted by size

find a dir

find file

find text in file by dir

100 - 199 [Informational]

101 Switching Protocols

200 - 299 [Success]

200 OK
203 Non-Authoritative Information (since HTTP/1.1)
204 No Content

300 - 399 [Redirection]

300 Multiple Choices
301 Moved Permanently
302 Found
304 Not Modified
307 Temporary Redirect (since HTTP/1.1)

400 - 499 [Client Error]

400 Bad Request
401 Unauthorized
402 Payment Required
403 Forbidden
404 Not Found
405 Method Not Allowed
408 Request Timeout
414 Request-URI Too Long
429 Too Many Requests
431 Request Header Fields Too Large

500 - 599 [Client Error]

500 Internal Server Error
501 Not Implemented
502 Bad Gateway
503 Service Unavailable
504 Gateway Timeout
505 HTTP Version Not Supported

The syntax of a HTTP header is as followed:
header_name[separated by colon][optional whitespace]field_value[CRLF]

Examples of HTTP headers

HTTP headers are classified into 4 main categories:

General headers, that carry general informations for both request and response, Request headers that are sent to the server, Response headers, that are sent from the server, and Entity Headers.

General Headers

General headers do appear in both request and response messages and provide very basic informations such as time, encoding, MIME or Caching.

Some important general Headers are for Example:

Request Headers

Request headers are sent in a request message only. These informations basically try to make the server sending are better response.
This header type is subdivided into 5 types: Informational headers, which handle very basic Client-Informations, accept headers, which tell servers client preferences and capabilities, conditional request headers to put restrictions on a request, security headers for client authentication and proxy headers.

Some informational headers:

Some accept headers:

Some conditional headers:

Some security headers:

Response Headers

Response headers are sent in response message from the server only, to provide the client with extra informations about the sender. These informations help clients to handle the response and make better requests in the future. This header type is subdivided into 3 subtypes: Informational headers, which provides basic Server-Informations, negotiation headers, and security headers.

Some informational response headers:

Some negotiation headers:

Some security headers:

BASIC HTTP CALL

do a simple http call on index of example.com

be silent...

add some Port... yawn...

include Header Output

Verbose Mode

DICT

Get the definition of the word SOLARIS. For in-depth understanding of the DICT-Protocol, have a look at Wikipedia DICT and for more detailled informations refer to RFC2229

Insecure HTTPS

Save OUTPUT in File

with flag -o you are able to save the output to a file on a disk

with flag --create-dirs cURL will even handle to create the local dir hierachy for you

Get some FTP File

Send a FTP NLSD command

list a directory on a FTP server

Upload some FTP File

Send some Headers

Send some custom Headers

GET some data

POST some data

Pass HTACCESS

Fake HTTP Referer

By the way, in RFC2068, the word Referrer is wrongly written as Referer [sic] and therefor now standard in the HTTP-Specification! This mistake was not adepted to the DOM Specifications. So this may explain the different notation.

FOLLOW LOCATION

When the server is sending in a redirect header (301, 302), cURL will follow

Send Cookies

For advanced Hacking, you often need to send some cookies. This one here is the simple method.
Dig the web for more detailed informations about cookie handling with cURL

Connect to a POP3-Server with TELNET

For example, you could login to your POP-Server and read your mails, if there's no mail client around. Works as well for checking, if the connection to a certain mailserver can be established at all.

First, establish a TELNET session using your favourite console, whereas 110 is the standard port of your pop3 server

Now, lets talk a bit to the POP3 deamon:

Explanation:
list gives you a list of your mails
retr 3 opens mail 3
top 1 0 opens mailheaders from mail 1
top 1 5 opens mail with the first 5 lines of mail 1

Connect to an IMAP-Server with TELNET

Working with IMAP is more complicated, because IMAP is far more complex than POP3. You should check RFC3501, if you are interested in this protocol. Via TELNET, you are able to remove, create and rename folders and read and write and change your mails serverside.

Here's a piece of code:

Loggin in using your username and password, again, data will be transferred unencrypted on the net

Get a list of all your folders on root level

Keep the session going, you can do this from time to time

List Sub-Folders in Folder "Sent"

Get status of Folder INBOX

opens folder INBOX in READ-ONLY mode (for writing, use SELECT)

fetch some flags

fetch header of mail 1

With IMAP, it's possible to establish an encrypted connection via open_ssl for example. Dig into the web, if you are interested in this topic. It's not easy though...

Get a HTTP-Resource with TELNET

Another useful task for TELNET is grabbing HTTP resources, for example a webpage.
Again, establish a TELNET session. 80 is the port, HTTP is commonly listening to:

Now, tell the webserver, which file you want to have, and which host he should use

Press ENTER twice, since this is the delimiter of the HTTP-Header and the body. Writing code, you would use something like this: \r\n\r\n

And here's the content:

Passing GET-Parameters is a piece of cake:

For Testing with POST, one should go the easier way and use cURL, wget or some scripting language. Telnet might not be the perfect tool for this kind of testing.

Get a HTTPS-Resource with TELNET

Sending custom headers to a https website, using open_ssl and s_client