Objectives: Learn common port numbers and services, and which transport protocol they use.
Prerequisites: you have to know about TCP/IP protocols in general.
Key terms: port numbers, network, common, protocol, services
Network ports are provided by the TCP or UDP protocols at the Transport layer. They are used by protocols in the upper layers of the OSI model. Port numbers are used to determine what protocol incoming traffic should be directed to. Ports allow a single host with a single IP address to run network services. Each port number identifies a distinct service, and each host can have 65535 ports per IP address. Port use is regulated by the Internet Corporation for Assigning Names and Numbers (ICANN). By ICANN there are three categories for ports:
- From 0 to 1023 – well known ports assigned to common protocols and services
- From 1024 to 49151 – registered ports assigned by ICANN to a specific service
- From 49152 to 65 535 – dynamic (private, high) ports range from 49,152 to 65,535. Can be used by any service on an ad hoc basis. Ports are assigned when a session is established, and released when the session ends.
Well known ones are:
| Port | Service name | Transport protocol |
|---|---|---|
| 20, 21 | File Transfer Protocol (FTP) | TCP |
| 22 | Secure Shell (SSH) | TCP and UDP |
| 23 | Telnet | TCP |
| 25 | Simple Mail Transfer Protocol (SMTP) | TCP |
| 50, 51 | IPSec | |
| 53 | Domain Name System (DNS) | TCP and UDP |
| 67, 68 | Dynamic Host Configuration Protocol (DHCP) | UDP |
| 69 | Trivial File Transfer Protocol (TFTP) | UDP |
| 80 | HyperText Transfer Protocol (HTTP) | TCP |
| 110 | Post Office Protocol (POP3) | TCP |
| 119 | Network News Transport Protocol (NNTP) | TCP |
| 123 | Network Time Protocol (NTP) | UDP |
| 135-139 | NetBIOS | TCP and UDP |
| 143 | Internet Message Access Protocol (IMAP4) | TCP and UDP |
| 161, 162 | Simple Network Management Protocol (SNMP) | TCP and UDP |
| 389 | Lightweight Directory Access Protocol | TCP and UDP |
| 443 | HTTP with Secure Sockets Layer (SSL) | TCP and UDP |
| 989, 990 | FTP over SSL/TLS (implicit mode) | TCP |
| 3389 | Remote Desktop Protocol | TCP and UDP |
The meaning of DNS is Domain Name System
Changed to Domain Name System
DNS Stand for Domain Naming Service.
It is Domain Name Server too
Domain Name Server is wrong
No, it’s not. The “S” in “DNS” stands for “System” as DNS can also be a protocol.
It could also be a query, which is a Domain Naming System query. DNS does not necessary reference a server when we talk about the protocol — Domain Name System queries reach out and query a Domain Name System server hence “DNS Server”.
The “Server” aspect of DNS is only a small subset of what DNS is, so calling it by its less generic name could be misleading.
No its Domain name system because DNS is a server only the work of DNS is to convert domain name to ip address and ip address to domain name. That means lets us try to understand it in a simple example EX-if you want to search http://www.example.org this is a domain but computer does not able to understand the name system can only understand to ip address for share packet(packet: establish connection between two device) so that why DNS convert this name http://www.example.org to a ip address (ip address is like a path just like your postal pin code) then our system able to show us the HP website. But if you already know the ip address of HP website you can put it in your browser it also show you the same result. Before DNS there was an another server called WINS it converts only NetBios to ip address, NetBios is difficult to understand because it has 16digit alpha numeric so for that DNS was invented. This is the full work of DNS it is a process/system to convert ip to domain and domain to ip so we can not not say Domain Name Server.
Well explained! DNS : The protocol that resolves website names into IP addresses e.g. http://www.Facebook.com is the domain name or the name of the website and it has to be converted to an IP address , which is 102.132.100.35. Then this IP address will also be converted to binary digits (bits).
All this process of converting the domain name to an IP address helps the computer to understand as we all know that computers only understands 0(s) and (1s).
only domain name system. and its a type of server so its not domain name server… plz correct this
Hi, u forget to add 3389 )
Added
what is the port number of ICMP
ICMP is a network layer protocol. There is no TCP or UDP port number associated with ICMP packets as these numbers are associated with the transport layer above. From Wikipedia: https://en.wikipedia.org/wiki/Internet_Control_Message_Protocol
Where is default proxy port 8080?
Default Proxy port no. is 3128
How about adding port 445 Server Message Block (SMB)
all these comments are making me feel intelligent :’D
Port 135 is reserved for RPC (Remote Protocol Call)/DCOM using both TCP and UDP,
Only ports 137, 138 and 139 are reserved for NETBIOS
50, 51 IPSec port it’s wrong>>>> 50 and 51 are the layer 4 protocols AH and ESP ipsec would normaly use udp 500 or 4500 as ports
What is the reason for using Secure Shell (SSH) instead of Telnet?
The key difference between Telnet and SSH is that SSH uses encryption, which means that all data transmitted over a network is secure from eavesdropping.