SocketFileTransfer-C

A client-server application for secure file transfer with authentication, implemented using TCP sockets in C. The server validates user credentials and handles file uploads/downloads, while the client interacts with the server to perform these operations.

Features

• Authentication: Validates username and password (default: admin/password123).
• File Upload: Clients can send files to the server (saved as uploaded_<filename>).
• File Download: Clients can request files from the server (saved as received_<filename>).
• Error Handling: Basic error checks for invalid credentials, missing files, and connection issues.

Prerequisites

• gcc compiler
• Unix-like environment (tested on Linux)
• Basic C libraries (libc, pthread, etc.)

Usage

Compilation

Compile the server and client programs:

gcc socket_server.c -o server
gcc socket_client.c -o client

Running the Server

1. Start the server first:

   ./server

2. The server listens on port 2120 (ensure the port is available and not blocked by a firewall).

Running the Client

1. Run the client and connect to the server:

   ./client

2. Enter credentials:
   • Username: admin
   • Password: password123
3. Choose an operation:
   • Download: Request a file from the server.
   • Upload: Send a file to the server.

Notes

• Update SERVER_IP in socket_client.c to match your server's IP address before compiling.
• The server handles one client at a time (single-threaded).

Code Structure

• socket_server.c: Server-side code for authentication and file management.
• socket_client.c: Client-side code for user interaction and file transfer.