What is TCP/IP?
. Transmission Control Protocol/Internet Protocol is the basic communication protocol of the internet.
. Specifies how data is exchanged over internet by providing end-to-end communication.
. Handles how data should be broken into packets, addressed, transmitted, routed and received at destination.
. Each of the two protocols have different functionality.
. Specifies how data is exchanged over internet by providing end-to-end communication.
. Handles how data should be broken into packets, addressed, transmitted, routed and received at destination.
. Each of the two protocols have different functionality.
Port:
. IP Address identifies a device on a computer.
. This IP address alone is not sufficient to transfer data as computer can run multiple applications.
. So, IP identifies computer, Port identifies application/service running on computer.
. Port number is a 16 bit integer ranging from 0 to 65535.
. Port number is a 16 bit integer ranging from 0 to 65535.
. Port Numbers are standardized by IANA and they are present in header section of packet which is being transmitted.
. By these port numbers, the purpose of packet is known. Example:Web, email etc.
Different TCP/IP ports:
| Protocol | Port Number | Used for: |
|---|---|---|
| File Transfer Protocol (FTP) | 20/21 | FTP control is handled on port 21 and data is transfered on port 20 |
| Secure Shell (SSH) | 22 | To manage network devices securely |
| Telnet | 23 | To manage network devices securely, but it is not as secure as SSH |
| Simple Mail Transfer Protocol (SMTP) | 25 | To transfer email to server |
| Domain Name System (DNS) | 53 | To translate domain names into IP addresses |
| Dynamic Host Configuration Protocol (DHCP) | 67/68 | To assign dynamic IPs in a network |
| Hyper Text Transfer Protocol (HTTP) | 80 | Web browsers |
| Post Office Protocol (POP) | 110 | To retrieve mail from servers |
| Internet Mail Access Protocol (IMAP) | 143 | Retrieves mail from servers, advanced version of POP |
| Hyper Text Transfer Protocol over SSL (HTTPS) | 443 | HTTP in conjunction with SSL |
| File Transfer Protocol over SSL (FTPS) | 989 | FTP in conjunction with SSL |