In-Depth Notes on FTP and TFTP textbook

21.1 FTP

• Definition: File Transfer Protocol (FTP) is the standard mechanism provided by TCP/IP for transferring files between hosts.
• Challenges:
  • Different file name conventions between systems
  • Different representations for text and data
  • Different directory structures
• Solution: FTP resolves these issues elegantly, allowing for effective file transfers despite differences.
• Protocol Overview:
  • Uses TCP, which is connection-oriented, ensuring reliable data transfer.
  • Requires two TCP connections:
  • Control connection on well-known port 21
  • Data connection on well-known port 20

21.2 FTP Operation

• Control Connection:

  • Step 1: Server performs a passive open on port 21.
  • Step 2: Client performs an active open using an ephemeral port.

• Data Connection:

  • Step 1: Client sends a passive open request.
  • Step 2: Port number for data transfer is sent through the control connection.
  • Step 3: Server performs an active open on the ephemeral port provided by the client.

21.3 File Transfer Details

• File Transfer Process:

  • The client specifies the file type, data structure, and transmission mode.
  • Ensures that both local and remote file systems are compatible during the transfer.

• Example: Illustrates a directory listing retrieval using FTP. The client sends commands to the server, displayed with responses indicating successful connections and data transfers.

21.4 Anonymous FTP

• Purpose: Allows users to access public data without needing specific credentials.
• Example: Public data available at internic.net demonstrates the functionality of anonymous FTP.

21-2 TFTP

• Definition: Trivial File Transfer Protocol (TFTP) is used for simpler file copying needs without the complexities of FTP.
• Use Case: Ideal for situations like booting diskless workstations or routers where only configuration and bootstrap files are needed.
• Protocol Overview:
  • Runs over UDP (User Datagram Protocol).
  • Uses well-known port 69 for file transfers, enabling quick and simple file copying tasks without overhead.