EtherToTransStack is a comprehensive implementation of a network protocol stack built from scratch, starting from the Ethernet layer up to the Transport layer (TCP). This project provides a fully functional networking stack that operates on virtual network interfaces and implements essential networking protocols.

The stack is organized in a layered architecture:

• Ethernet frame handling
• Device management for network interfaces
• Support for sending and receiving raw Ethernet frames
• MAC address resolution

• IP packet processing and forwarding
• ARP protocol implementation for address resolution
• Custom routing protocol (similar to RIPv2)
• IP fragmentation and reassembly

• Complete TCP implementation
• Connection establishment and termination (SYN, FIN sequences)
• Flow control with sliding window
• Retransmission mechanisms
• Socket API for application integration

• Modular Design: Clear separation between networking layers
• Protocol Support: Implements Ethernet II, ARP, IP, and TCP protocols
• Routing Capabilities: Custom routing protocol for packet forwarding
• Thread Safety: Mutex-protected shared resources
• Debugging Tools: Packet tracing and network state inspection
• Test Applications: Echo servers, packet senders/receivers, and routing tests

src/
├── include/           # Header files
│   ├── link/          # Link layer interfaces
│   ├── network/       # Network layer interfaces
│   └── transport/     # Transport layer interfaces
├── link/              # Link layer implementation
├── network/           # Network layer implementation
├── transport/         # Transport layer implementation
└── test/              # Test applications
    ├── eth_sender     # Ethernet frame sender
    ├── eth_receiver   # Ethernet frame receiver
    ├── arp_sender     # ARP requester
    ├── arp_receiver   # ARP responder
    ├── ip_sender      # IP packet sender
    ├── router         # Routing test application
    ├── echo_client.c  # TCP echo client
    └── echo_server.c  # TCP echo server

• Uses libpcap for accessing network interfaces
• Custom implementation of protocol headers and state machines
• Socket API compatible with standard socket programming
• Support for routing between multiple virtual interfaces
• ARP cache for efficient address resolution
• TCP connection state management following RFC specifications

The project uses Make for building:

# Build the entire stack
cd src
make

# Build specific components
cd src/link
make
cd ../network
make
cd ../transport
make

# Build test applications
cd ../test
make

Various test applications are provided to verify the functionality of each layer:

• eth_sender and eth_receiver: Test Ethernet frame transmission
• arp_sender and arp_receiver: Test ARP protocol functionality
• ip_sender: Test IP packet transmission
• router: Test routing capabilities
• echo_client and echo_server: Test TCP connection and data transfer

• libpcap
• POSIX threads library
• Standard C library

This project is an educational implementation of networking protocols.