How do raw sockets work?

Raw sockets work by allowing applications to bypass the standard transport layer protocols (like TCP and UDP) and directly interact with the network layer. Here's how they function:

Socket Creation: An application creates a raw socket using system calls (e.g., socket() in C) with a specific protocol type, such as IPPROTO_RAW.
Packet Crafting: The application constructs the entire packet, including headers and payload. This includes specifying the IP header, transport layer headers, and any application data.
Sending Packets: The application sends the crafted packet using the sendto() function. The operating system then transmits the packet over the network.
Receiving Packets: The application can also receive packets using the recvfrom() function. It can capture all incoming packets, regardless of their protocol, allowing for detailed analysis.
Bypassing Protocol Stack: Since raw sockets operate at a lower level, they can manipulate packet headers and contents directly, which is not possible with standard sockets.
Privileges: Raw sockets typically require elevated privileges (like root access) to prevent misuse, as they can be used to create malicious traffic.

This low-level access enables a wide range of applications, from network diagnostics to security testing.