TCP and UDP: Network Communication Protocols

TCP and UDP: Key Differences

UDP (User Datagram Protocol)

  • Data-oriented
  • Unreliable, connectionless
  • Simple
  • Supports Unicast and Multicast
  • Used by SNMP

TCP (Transmission Control Protocol)

  • Stream-oriented
  • Reliable, connection-oriented
  • Complex
  • Unicast only
  • Common Use Cases:
    • Used by most Internet applications
    • Web (HTTP)
    • Email (SMTP)

Fragmentation

DF (Don’t Fragment):

  • 1: Don’t Fragment
  • 0: Could Fragment

MF (More Fragment):

  • 1: More fragmentation needed
  • 0: No more fragmentation needed, last fragment.

All fragments of one packet

Read More

TCP Protocol: Exercises, Flow Control, Congestion & Error Management

TCP Protocol: Exercises and Mechanisms

TCP Exercise 1: Suppose a TCP connection is transferring a file of 5000 bytes. The first byte is numbered 10001. What are the sequence numbers for each segment if data is sent in five segments, each carrying 1000 bytes?

The following shows the sequence number for each segment:

  • Segment 1 ➡ Sequence Number: 10,001 (range: 10,001 to 11,000)
  • Segment 2 ➡ Sequence Number: 11,001 (range: 11,001 to 12,000)
  • Segment 3 ➡ Sequence Number: 12,001 (range: 12,001 to 13,000)
Read More

Digital Signatures, OSI Model, and Network Attacks

Digital Signatures and Encryption

Digital Signature: A cryptographic method that ensures the identity of the sender in messages and documents. It uses two keys: a public key (Kp) and a secret key (Ks). The message is signed using the private key: F(M, Ks) = S

PGP (Pretty Good Privacy)

A system used for encryption and decryption to protect information that travels over the internet (including email) and other files (such as those stored on a hard drive). The system is based on public-key cryptography.

Read More

Networking Fundamentals: Ethernet, IP, VLANs, and More

Topic 2: The 802 Project and Ethernet Standards

The 802 project, supported by ISO, divides the data link layer into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC). It defines the specific aspects of each local area network.

Main Features of Ethernet Standards:

  • 10BASE5: Uses 500m of coaxial cable (50 ohm) with PCs connected every 2.5m.
  • 10BASE2: Uses 185m of coaxial cable (50 ohm) with a maximum of 30 PCs and BNC connectors.
  • 10BASET: Uses twisted pair cables with hubs and switches.
Read More

DHCP and SSH Services: Configuration, Security, and Encryption

DHCP Service Explained

Item 8. What is the DHCP service? Dynamic Host Configuration Protocol (DHCP) offers fast network configuration for clients. The administrator can assign dynamic IP addresses to clients through the DHCP server, without requiring manual configuration of IP, subnet mask, gateway, etc. The DHCP protocol uses UDP ports 67 and 68 for communication between server and client.

The DHCP server can automatically configure:

  • Client IP address
  • Subnet Mask
  • Lease time
  • Renewal time
  • Rebinding time

DHCP

Read More

Understanding Domain Names and DNS Configuration

Domain Names

A domain name is a unique string of characters that corresponds to a unique IP address. For example, the domain name www.cs.umb.edu corresponds to the IP address 158.121.106.222. You can use either, but the domain name is easier to remember.

Domain Name System (DNS)

The Domain Name System (DNS) is the process of turning a domain name into an IP address. It’s like a phone book for the internet. This system is governed by the DNS protocol. The Domain Name System is hierarchical.

The Domain

Read More