Network monitoring and port specification.

For a formal definition, we can say,

“ A port number is the logical address of each application or process that helps in identifying the sender and receiver processes of messages.”

Each port number is a 16-bit number ranging from 0 to 65535.

Well-known Port Numbers :- Port Numbers reserved for use by some popular application protocols.

But what exactly port number ?

IP address has been used to reach the destination computer. But now, how to identify the correct socket to reach the destined process? For this, the sockets are assigned special numbers called “Port Numbers” , which help to identify the exact sender and receiver processes (applications/ programs). So, along with IP address, port numbers are also provided and both of these work together to locate the destination computer and then the destined process.

 (quora.com)

From webopedia--- 

Port Number ---	Description
1	TCP Port Service Multiplexer (TCPMUX)
5	Remote Job Entry (RJE)
7	ECHO
18	Message Send Protocol (MSP)
20	FTP -- Data
21	FTP -- Control
22	SSH Remote Login Protocol
23	Telnet
25	Simple Mail Transfer Protocol (SMTP)
29	MSG ICP
37	Time
42	Host Name Server (Nameserv)
43	WhoIs
49	Login Host Protocol (Login)
53	Domain Name System (DNS)
69	Trivial File Transfer Protocol (TFTP)
70	Gopher Services
79	Finger
80	HTTP
103	X.400 Standard
108	SNA Gateway Access Server
109	POP2
110	POP3
115	Simple File Transfer Protocol (SFTP)
118	SQL Services
119	Newsgroup (NNTP)
137	NetBIOS Name Service
139	NetBIOS Datagram Service
143	Interim Mail Access Protocol (IMAP)
150	NetBIOS Session Service
156	SQL Server
161	SNMP
179	Border Gateway Protocol (BGP)
190	Gateway Access Control Protocol (GACP)
194	Internet Relay Chat (IRC)
197	Directory Location Service (DLS)
389	Lightweight Directory Access Protocol (LDAP)
396	Novell Netware over IP
443	HTTPS
444	Simple Network Paging Protocol (SNPP)
445	Microsoft-DS
458	Apple QuickTime
546	DHCP Client
547	DHCP Server
563	SNEWS
569	MSN
1080	Socks

For details about the port number , you may also read.

• List of TCP and UDP port numbers.

• Types of port numbers 

  MONITOR YOUR NETWORK:
  

  tracert

  ping

  ipconfig

  arp 

  netstat 

  nbtstat

  nslookup 

  pathping

  route

  getmac

  This is the list for all the windows commands...