TELNET Protocol Implementation

This a P2P implementation of telnet. This program transfers data on TCP sockets as plain text. However there is also an option to send and recieve messages in encryption mode. It uses the rsa module to generate public and private keys and a handshake is done between client and server to transfer their public key to the otherside.

This is not a complete implementation in telnet protocol based on rfc854. There is no option negotiation to establish an NVT

This script could be used for:

1. Sending plain and encrypted text messages to server
2. Upload and download files to and from a peer
3. Execute commands on another peer and get the results
4. Scan open ports of a host
5. Send other requests such as SMTP or HTTP requests to servers.

This program uses PostgreSQL to save commands entered on client side on telnet_history database. When you run program in client mode it asks for username and password to connect to Postgre database.

You need to run this script as 2 proccesses for client and server mode.

To exit the program press Ctrl+c.

Server Mode

To run in server mode you need to run the following command in terminal:

>python3 main.py server [portnumber] [-e]

portnumber is the port server is going to listen on.

-e should be provided if you would like to enter encrypted mode.

Client Mode

To run in client mode you need to run the following command in terminal:

>python3 main.py client

• To establish a connection:

  telnet> open [host] [port] [-e]
  

  When connection is established you can:

  1. Send message to another peer:

     127.0.0.1:2250> send message
     hi
     done
     

  2. Send message to a remote SMTP or HTTP server:

     301 Moved

     The document has moved here. Server response recieved! ">

     google.com:80>send remote
     GET / HTTP/1.1
     HOST: google.com
     
     done
     
     Waiting for server...
     HTTP/1.1 301 Moved Permanently
     Location: http://www.google.com/
     Content-Type: text/html; charset=UTF-8
     Date: Sun, 30 May 2021 11:24:52 GMT
     Expires: Tue, 29 Jun 2021 11:24:52 GMT
     Cache-Control: public, max-age=2592000
     Server: gws
     Content-Length: 219
     X-XSS-Protection: 0
     X-Frame-Options: SAMEORIGIN
     
     
     
     301 Moved
     The document has moved
     here.
     
     Server response recieved!
     

  3. Upload a file to a peer:

     127.0.0.1:2250> upload [path]
     

  4. Download file from a peer:

     127.0.0.1:2250> download [path]
     

  5. Execute a command on peer:

     127.0.0.1:2250> exec [command]
     

  6. Disconnect:

     127.0.0.1:2250> quit
     

• To scan 1 to 1024 ports from start_ip to end_port:

  telnet> scan [start_ip] [end_ip]
  

• You could also see the previouse commands:

  telnet> history