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Network Protocols (Set of Rules)

What?

  • Networking protocols are like the rules of a game that ensure all participants play correctly and understand each other, crucial for the smooth operation of internet communications and web applications.

Network protocols

Why?

  • Standardization: Makes sure different devices and software can communicate.
  • Efficiency: Optimizes the use of network resources.
  • Security: Protects data from unauthorized access and tampering.
  • Reliability: Ensures data is accurately and consistently delivered.
  • Scalability: Facilitates network growth and management.

How?

OSI Layer 7: Application Layer

  • HTTP/HTTPS (HyperText Transfer Protocol/Secure)

    • What? : HTTP is for web data transfer, HTTPS adds encryption.
    • Why? : Browsing websites, accessing web services securely.
    • How? : curl https://www.google.com for HTTPS interaction.

  • DNS (Domain Name System)

    • What?: Translates domain names to IP addresses.
    • Usage: Resolving domain names to access websites.
    • How to check? : nslookup www.google.com for DNS resolution.

  • FTP (File Transfer Protocol)

    • How?: Transfers files between client and server.
    • Why?: Uploading/downloading files to/from servers.
    • How to check? : ftp www.google.com for FTP access.

OSI Layer 6: Presentation Layer

  • SSL/TLS (Secure Sockets Layer/Transport Layer Security)
    • How?: Provides encryption, data integrity, and authentication for secure communication.
    • Why?: Ensures secure transmission of sensitive data over the internet.
    • How to check?: Use openssl s_client -connect www.google.com:443 to inspect SSL/TLS connection.

OSI Layer 5: Session Layer

  • There is no Obvious Protcol here , Operating System maintains this layer.
  • Session Establishment:
    • How?: Handled by application layer protocols or the operating system's networking stack.
    • Why?: Initiates communication sessions between applications.
  • Data Synchronization:
    • How?: Managed within application layer protocols (e.g., TCP) or the OS networking stack through sequencing and flow control.
    • Why?: Ensures orderly and reliable data transmission.
  • Session Management:
    • How?: Application logic or the OS manages session timeouts, reconnections, and state.
    • Why?: Maintains session integrity and continuity.
  • Session Termination:
    • How?: Initiated by applications or the OS by closing connections and releasing resources.
    • Why?: Ends communication sessions when no longer needed.

OSI Layer 4: Transport Layer

  • TCP (Transmission Control Protocol)

    • How? : Ensures reliable, ordered delivery of data.
    • Why? : Transmission of web data.
    • How to check? : netstat | grep tcp (t in atn - for TCP connectivity check).

  • UDP (User Datagram Protocol)

    • How?: Provides faster but less reliable data transmission.
    • Why? : Real-time applications like streaming.
    • How to check? : netstat | grep udp (u in aun - for UDP connectivity check).

OSI Layer 3: Network Layer

  • IP (Internet Protocol)

    • How?: Routes packets across networks.
    • Why?: Identifying and addressing devices.
    • How to check? : traceroute www.google.com for packet path analysis.

  • ICMP (Internet Control Message Protocol)

    • How?: Handles network error messages.
    • Why? : Network troubleshooting.
    • How to check? : ping www.google.com for reachability check.
  • DHCP (Dynamic Host Configuration Protocol)
    • How? : Dynamically assigns IP addresses to devices.
    • Why? : Simplifies network setup and management.
    • How to check? : No direct commands.

OSI Layer 1: Physical Layer

  • Ethernet
    • What? : Physical connection standard.
    • Why? : Wired network connections.
    • How to check? : No direct commands.