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What are the Port Numbers in networking?

A port number is a logical address of each application (way to identify a specific process) or process that uses a network or the Internet to communicate. A port number is used to uniquely identify network-based applications.

Port numbers consist of 16-bit numbers, and these numbers are assigned automatically by the Operating System, manually by the user.

Who assigns the port address?

Internet Assigned Numbers Authority (IANA) assigns port numbers.

What are the common port numbers in Networking

Here is the list of most common port numbers in networking:

Port Number Usage
20 File Transfer Protocol (FTP) Data Transfer
21 File Transfer Protocol (FTP) Command Control
22 Secure Shell (SSH)
23 Telnet - Remote login service, unencrypted text messages
25 Simple Mail Transfer Protocol (SMTP) E-mail Routing
53 Domain Name System (DNS) service
80 Hypertext Transfer Protocol (HTTP) used in World Wide Web
110 Post Office Protocol (POP3) used by e-mail clients to retrieve e-mail from a server
119 Network News Transfer Protocol (NNTP)
123 Network Time Protocol (NTP)
143 Internet Message Access Protocol (IMAP) Management of Digital Mail
161 Simple Network Management Protocol (SNMP)
194 Internet Relay Chat (IRC)
443 HTTP Secure (HTTPS) HTTP over TLS/SSL

For me, the most common port numbers are 80, 443, 20, 21, 22, 23, 25, 67, and 53. If you are working in a computer-related technical field, then you should memorize all these basic networking protocols.

Active Directory ports List

If you are working in Windows based Active Directory then, you should remember all these important port numbers.

Active Directory Replication Port Number List

Port Number Usage
135 RPC ( Remote Procedure Call)
389 LDAP
3268 Global Catalog LDAP
3269 Global Catalog LDAP SSL
53 Domain Name System (DNS) service
88 Kerberos
445 SMB

People also ask

What is the Highest TCP Port Number Allowed?

Well, Most of the port numbers are mainly used in TCP and UDP-based networks. The highest TCP port number is (2^16 - 1) or 65,535.

How to check Port numbers?

To check your port numbers you have to open the command prompt and press (Window + R) and type “netstat -a” on Command Prompt and hit the Enter button. It'll show your active TCP connections. You'll see the port number just after the IP address. There is a colon : that will separate the IP address and port number.

For Example: If the command shows then is your IP address and 80 is your port number.

What is the Port and IP address?

The IP address is a 32-bit address that uniquely identifies any machine over the Internet, while the Port number is the address of the service within the System.

If we combine the IP address and port number then we call it Socket. Socket is the combination of the Port number and IP address, which is used to identify machines and the services within the machine. It works internally and externally and works as a gateway.

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