Computer Network Tutorial

Introduction of Computer Network Types of Computer Network Network Topology Computer Networking Architecture Transmission Modes (Data Flow) Basic Networking Devices Integrate Services Digital Network (ISDN)

Model

OSI Model TCP/IP Model

Physical Layer

Digital Transmission Analog Transmission Transmission Media Switching

Data Link Layer

Error detection and Error correction Data Link Control Multiple Access Aloha

Network Layer

Network Layer - Logical Address Address Mapping Unicast Routing Protocol

Transport Layer

Process to Process Delivery User Datagram Protocol Transmission Control Protocol Stream Control Transmission Protocol Session Layer and Presentation Layer

Application Layer

Domain Name System Application Protocol E-mail Cryptography

Misc

Classes of Routing Protocols Classification of Routing Algorithms Controlled Access Protocols in Computer Networks Differences between IPv4 and IPv6 Fixed and Flooding Routing Algorithms Advantages and Disadvantages of Fibre Optics Cable APIPA Difference between Active and Passive FTP Fiber Optics and its Types Method of Joining and Fusion of Fiber Optic Cable Define Framing in Computer Network Disadvantages of Computer Network Mesh Topology Diagram in Computer Network Ring Topology in Computer Network Star Topology in Computer Networks 4G Mobile Communication Technology Advantages and Disadvantages of LAN Advantages and Disadvantages of MAN Advantages and Disadvantages of WAN Application Layer in OSI Model Cyclic Redundancy Check Example Data link layer in OSI model Difference between Transport and Network Layer Hamming Code Example Network Layer in OSI Model Session Layer in OSI Model Transport Layer in OSI Model Two Port Network in Computer Networks Uses of Computer Networks What is Computer Network What is Framing in a Computer Network Advantages and Disadvantages of Bus Topology Difference between Star Topology and Bus Topology Subnetting in Computer Network Subnetting Questions and Answers What is Bus Topology What is Network Topology and Types in Computer Networks Access Control in Networking Basic Characteristics of Computer Network Benefits of SOCKS5 Proxy in Computer Networks Computer Network viva Questions Difference between BOOTP and RARP Difference Between Network Topologies and Network Protocols Difference between NFC and RFID Difference Between Point-to-Point Link and star Topology Network Differences Between MSS and MTU Differences Between Trunk Port and Access Port Different Modes of Communication in Computer Networks MIME Protocol in Computer Networks Modes of Communication in Computer Networks Network Attack in Computer Network Port Address in Networking Simplest Protocol in Computer Network Sliding Window Protocol in Computer Network Stop And Wait Protocol in Computer Networks TCP 3-Way Handshake Process in Computer Networks What is a Proxy Server What is APPN What is ICMP Protocol What is Point-to-Point Protocol What is Port Address in Networking What is the HDLC Protocol What is VRRP Protocol Difference Between Analog and Digital Signals Difference Between Hub and Repeater Difference between Repeater and Switch Difference Between Transparent Bridge and Source Routing Bridge Source Routing Bridge in Computer Networks Transparent Bridge in Computer Networks Transport Protocol in Computer Networks Types of CSMA in Computer Networks What is Wired and Wireless Networking Network Security in Computer Network Disadvantages of Extranet Difference Between TELNET and FTP Define Protocol in Computer Networks Guided Transmission Media in Computer Network What is a Gateway in a Computer Network IGMP in Computer Networks LAN Protocols in Computer Networks MAN Meaning in Computer Modulation Techniques in Computer Networks Switching in DCN TCP/IP Applications What is IGMP? What is Modem in Networking What is Non-Persistent CSMA Difference between Cell Splitting and Cell Sectoring Forouzen Computer Network Open Loop and Closed Loop Congestion Control Types of Cluster Computing WAP-Wireless Access Point What are the elements of the Transport Protocol Difference between Gateway and Switch Flow Control in Data Link Layer Body Area Network Flooding in Computer Network Token Ring in Computer Networks VoIP in Computer Networks What is Infrared Transmission Congestion Control Techniques Forward Error Correction (FEC) Switching Techniques What is Telnet in Computer Network What are the Types of IPv4 Addresses IEEE 802.6 (DQDB) IEEE 802.15.4 Technology What is HDLC (High-level Data Link Control)? What is SMS Hubbing in Telecom? Circuit Switching in Computer Networks Communication Satellites in Computer Networks Features of HTTP Protocol IMAP4 (Internet Message Access Protocol) Internet Services How to Set up a Wireless Router Internetwork Routing in Computer Networks Distributed Computing System Features of GSM The 802.11 MAC Sublayer Protocol What is IEEE 802.3? What are Hubs and Switches in Computer Networks? What is Modem in a Computer Network? What is multicasting in Computer Networks? GSM -The Mobile Station What is Network Server? Slotted Aloha in Computer Network What is Ethernet in Computer Networks What is Arpanet? Radio Access Network (RAN) TCP 3-Way Handshake Process PING SWEEP (ICMP SWEEP) Print Server Private IP Address Security Services in Computer Networks Protocol Data Unit (PDU) CSMA with Collision Avoidance (CSMA/CA) What is Gateway in Computer Network? Advantages of Networking Data Link Layer Design Issues DHCP in Computer Networks Internet Security Association and Key Management Protocol (ISAKMP) What is Switch Hub? Telnet Full form in Networking Multimedia Systems Quality of Service in Computer Networks What is Carrier Sense Multiple Access (CSMA)? What is Circuit Switching What is Duplex Network? What is Web Protocol Network LAN Technologies Classes in Computer Network Low-Density Parity Check (LDPC) Wireless Internet Service Providers(Wisps) What is Handshaking? Cache Server What Is WSN Network? Check Sum Error Detection Linear Bus Topology Functions of the Transport Layer Infrared Transmission in Computer Networks Digital Signal in Computer Network Digital Data Transmission in Computer Networks Define Checksum with Example Computer Network Security Requirements Brust Errors in Computer Network Back Side Bus (BSB) 2-Dimension Parity Check in Computer Network Router and Brouter Microwave Transmission in Computer Networks Magnetic Media in Computer Network A One-Bit Sliding Window Protocol CDMA-Near-Far Problem Reference Models in Computer Networks Uni-cast, Broadcast, and Multicast in Computer Networks Uses Of Bridges in Computer Networks What are Gateways in Computer Network?

TCP Ports

What is TCP?

TCP is a transport layer protocol that helps to establish connections. TCP means Transmission Control Protocol. It guarantees secure data transmission between two network-connected devices. The data can only be sent when a secure connection has been established.

The receiver sends an acknowledgment of receiving the data after receiving it. To transfer data between devices, it uses data blocks. It has more system functionalities, including flow control, error control, and congestion control, but it transmits data slowly. The TCP header is 20-60 bytes long and contains a variety of information to improve reliability.  TCP is used by protocols like HTTP, FTP, etc. for secure data transmission over networks because of its dependability.

What is a Port?

A number is given to server applications and user sessions in an IP network. The Internet Assigned Numbers Authority (IANA) establishes port numbers and places them in the header section of packets so that they can be used to specify the various purposes such as Web, email, voice call, video call, etc.

For example, if we want to open the email and games applications on our computer, then  we have to send mail to the host through the email application, and we can play online games through the games application. These applications give various special numbers to perform all of these tasks. There is a port number for each address and protocol. TCP and UDP are the two protocols that primarily use the port numbers.

TCP ports are those that adhere to transmission control protocols. File Transfer Protocol ports (20 and 21), SMTP port (25), IMAP port (143), and Secure Shell port are the various TCP ports that are used for file transfers.

TCP ports establish connections before sharing data. Suppose, you call your friend to tell him about a new game or movie. Your friend will pick up the phone if he/she receives the call and verifies that it is you on the other end of the line. After then, you can start telling him/her about the game.
TCP ports operate similarly. Data is transmitted only after a secure connection has been established between the sender and the receiver. The three-way handshake is used for sending or receiving data between the devices that use TCP ports.

What is a three-way handshake?

Three-way handshake is used by TCP ports to create secure connections. When using TCP, the sending device creates a connection with the receiving device.

The three messages SYN, SYN-ACK, and ACK are used to represent the three distinct interactions that make up a three-way handshake. The first segment is called SYN. The sending device sends a SYN (synchronized sequence number) message to the receiving computer.

It's attempting to say, "Hello! Are you open to making a connection?"

When a device receives a connection request and the receiver is prepared to establish a connection, it responds with a SYN-ACK segment.  The SYN-ACK segment responds with a synchronized sequence number after acknowledging the connection request. In simple terms, the device is indicating that it is willing to establish a connection and that it has acknowledged your request.

When this occurs, the sending device notifies the receiving device that its message has been acknowledged by sending an ACK segment. After that, a connection is established, and data transfer starts. When the data is transmitted completely, then the connection is automatically broken.

By doing this, it is assured that all data sent to the receiving device is correct and sent in the right order. Additionally, no packets are missing because a connection was established first.

Another way of using TCP Ports?

Enterprise applications such as Oracle, SQL, and SharePoint require you to configure services on specific port numbers. To enable traffic to flow on those port IDs, it is crucial to cooperate with your network administrator. For system security, firewalls keep an eye on ports.

For troubleshooting, we use port numbers. We can specifically detect malicious processes and troubleshoot malware.

Rules that indicate both aspects of a socket are frequently used in the firewall configuration. Using IP addresses, port numbers, or a combination of both, you can set up allowances or traffic blocks.

Port

In the TCP/IP model, there are a total of 65,535 ports available, each of which is a 16-bit unsigned integer. Consequently, the range of port number is from 0 to 65535. The zero-port number is unavailable in UDP but is reserved for TCP which cannot be used. The port numbers are assigned by a standardized organization called IANA (Internet Assigned Numbers Authority).

Different Types Of Ports?

There are 3 different types of Ports which are mentioned below:

  • Well Known Ports
  • Registered Ports
  • Dynamic Ports

Registered Port

The registered port range is from 1024 to 49151. The user processes the registered ports. Instead of the usual applications with a well-known port, these processes the individual applications.

Well Known Ports

Range of the well-known port is from 0 to 1023. The well-known ports are used with protocols like IMAP, HTTP, SMTP, etc. that support popular applications and services.

Dynamic Ports

Dynamic ports have a range of 49152 to 65535. Another name for the dynamic port is ephemeral port. These port numbers are given to the client application dynamically when a client establishes a connection. Clients are unaware of this port until they connect to a service.

How can you view your TCP Information?

TCPView.exe is highly advisable if you're using a Windows Operating System. Mark Russinovich was the original developer, and it is now a Microsoft asset. The tool also comes in a free command-line version called TCPVcon.

When you run TCPView, you may notice that you have a lot of remote connections running on your system. That is one of the reasons TCPView is such an effective tool for identifying rogue processes. It might be a Trojan horse, a backdoor administrative program that calls home.

Conclusion

In the TCP/IP model, there are a total of 65,535 ports available, each of which is a 16-bit unsigned integer. Consequently, the port number range is 0 to 65535. The zero-port number is unavailable in UDP but is reserved for TCP which cannot be used. The port numbers are assigned by a standardized organization called IANA (Internet Assigned Numbers Authority).