This is a basic implementation of an SSH client and SSH server. This implementation allows the client to perform certain basic commands in the server's terminal. The following are the commands that can be passed to the secure shell.

1. ls: To list files in the current directory of the server.
2. pwd: To show absolute path to the current directory of the server.
3. cd absolutepath: To change to the specified directory of the server.
4. cp src dest: To copy a file in the server from src to dest.
5. mv src dest: Move a file in the server from src to dest.

sudo apt install python3
sudo apt install python3-pip
pip3 install cryptography==3.3.1

1. Start SSH server. The server creates it's own pair of public and private keys and listens for connections on port 54321. Whenever a client connects to it, it transfers it's public key to the client.

./ssh_server.py

2. Start SSH client Once the client is registered with the server, it recieves the public key of the server. Using this public key, client encrypts the session key and succesfuly exchanges a secret key with the server. For encrypting the terminal commands send to the secure shell and any further communication, this exchanged session key is used.

./ssh_client.py -i <server_ip> -p <server_port_no> -n <user_name>
./ssh_client.py -i 127.0.0.1 -p 54321 -n john

Follow along with the prompts in the terminal to register a user with the server and to establish a connection.

NOTE:

• Only users registered with the server will be authenticated and given access to the server's shell.