SMTP - 25

SMTP is known as the Simple Mail Transfer Protocol. The primary purpose of this protocol is to make sure that email messages are communicated over the network securely. 

HTTP - 80

Port 80 is associated with HTTP, Hypertext Transfer Protocol. The main purpose of port 80 is to allow the browser to connect to the web pages on the internet.

HTTPS - 443

HTTPS - 443 is also associated with the TCP protocol. HTTPS port 443 also lets you connect to the internet by establishing a connection between the webpages and the browser.

FTP - 20, 21

FTP is the abbreviation of "File Transfer Protocol". The purpose of FTP is to transfer files over the internet. It basically lays down all the rules which are to be followed during the transfer of data.

Port 20 performs the task of forwarding and transferring of data. It takes over the task of transferring FTP data when it is in active mode.

Port 21 performs the task of signaling for FTP. It listens to all of the commands and provides a flow control for data. It is quite essential for maintaining the flow of data.

TELNET - 23

TELNET port 23 comes under the category of TCP Protocols. Its main function is to establish a connection between a server and a remote computer. It establishes a connection once the authentication method has been approved.

IMAP - 143

IMAP is the abbreviation of Internet Message Access Protocol. The primary purpose of this port is to retrieve emails from a remote server without having the need to download the email.

RDP - 3389

RDP is also known as the Remote Desktop Protocol. This port has been developed by Microsoft. It enables you to establish a connection with a remote computer.

SSH - 22

SSH is also referred to as Secure Shell. It carries out the task of remotely connecting to a remote server or host. It allows you to execute a number of commands and move your files remotely as well.

DNS – 53

DNS is referred to as Domain Name System. DNS makes use of relational databases to link the host names of the computers or networks to their respective IP Addresses. The port 53 waits for requests from DHCP to transfer the data over the network. It operates on the Application Layer of the TCP/IP Model.

DHCP - 67, 68

DHCP is also known as Dynamic Host Configuration Protocol. The basic purpose of DHCP is to assign IP Address related information to the clients on a network automatically. This information may comprise of subnet mask, IP Address etc.

UDP Port 67 performs the task of accepting address requests from DHCP and sending the data to the server.

UDP Port 68 performs the task of responding to all the requests of DHCP and forwarding data to the client.

POP3 - 110

POP3 is also referred to as Post Office Protocol Version 3. It allows the email messages to be retrieved from the SMTP servers. Using this port, you can download the messages from the server and then read them.