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Table Of Contents  The TCP/IP Guide
 9  TCP/IP Lower-Layer (Interface, Internet and Transport) Protocols (OSI Layers 2, 3 and 4)
      9  TCP/IP Transport Layer Protocols
           9  Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)
                9  TCP/IP Transport Layer Protocol (TCP and UDP) Addressing: Ports and Sockets

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TCP/IP Sockets and Socket Pairs: Process and Connection Identification
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TCP/IP User Datagram Protocol (UDP)
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Common TCP/IP Applications and Assigned Well-Known and Registered Port Numbers
(Page 2 of 2)

Common Well-Known Port Numbers and Applications

Table 145 lists the well-known port numbers for the most common TCP/IP application protocols.


Table 145: Common TCP/IP Well-Known Port Numbers and Applications

Port #

TCP / UDP

Keyword

Protocol Abbreviation

Application or Protocol Name / Comments

7

TCP + UDP

echo

Echo Protocol

9

TCP + UDP

discard

Discard Protocol

11

TCP + UDP

systat

Active Users Protocol

13

TCP + UDP

daytime

Daytime Protocol

17

TCP + UDP

qotd

QOTD

Quote Of The Day Protocol

19

TCP + UDP

chargen

Character Generator Protocol

20

TCP

ftp-data

FTP (data)

File Transfer Protocol (default data port)

21

TCP

ftp

FTP (control)

File Transfer Protocol (control / commands)

23

TCP

telnet

Telnet Protocol

25

TCP

smtp

SMTP

Simple Mail Transfer Protocol

37

TCP + UDP

time

Time Protocol

43

TCP

nicname

Whois Protocol (also called “Nicname”)

53

TCP + UDP

domain

DNS

Domain Name Server (Domain Name System)

67

UDP

bootps

BOOTP / DHCP

Bootstrap Protocol /
Dynamic Host Configuration Protocol (Server)

68

UDP

bootpc

BOOTP / DHCP

Bootstrap Protocol /
Dynamic Host Configuration Protocol (Client)

69

UDP

tftp

TFTP

Trivial File Transfer Protocol

70

TCP

gopher

Gopher Protocol

79

TCP

finger

Finger User Information Protocol

80

TCP

http

HTTP

Hypertext Transfer Protocol (World Wide Web)

110

TCP

pop3

POP

Post Office Protocol (version 3)

119

TCP

nntp

NNTP

Network News Transfer Protocol

123

UDP

ntp

NTP

Network Time Protocol

137

TCP + UDP

netbios-ns

NetBIOS (Name Service)

138

UDP

netbios-dgm

NetBIOS (Datagram Service)

139

TCP

netbios-ssn

NetBIOS (Session Service)

143

TCP

imap

IMAP

Internet Message Access Protocol

161

UDP

snmp

SNMP

Simple Network Management Protocol

162

UDP

snmptrap

SNMP

Simple Network Management Protocol (Trap)

179

TCP

bgp

BGP

Border Gateway Protocol

194

TCP

irc

IRC

Internet Relay Chat

443

TCP

https

HTTP over SSL

Hypertext Transfer Protocol over
Secure Sockets Layer

500

UDP

isakmp

IKE

IPSec Internet Key Exchange

520

UDP

router

RIP

Routing Information Protocol (RIP-1 and RIP-2)

521

UDP

ripng

RIPng

Routing Information Protocol - “Next Generation”


Common Registered Port Numbers and Applications

The registered port numbers are by definition for protocols that are not standardized using the RFC process, so they are mostly esoteric applications that I don’t feel there is much point in listing at length. Table 146 shows a few that I feel are of particular interest:


Table 146: Common TCP/IP Registered Port Numbers and Applications

Port #

TCP / UDP

Keyword

Protocol Abbreviation

Application or Protocol Name / Comments

1512

TCP + UDP

wins

WINS

Microsoft Windows Internet Naming Service

1701

UDP

l2tp

L2TP

Layer Two Tunneling Protocol

1723

TCP

pptp

PPTP

Point-To-Point Tunneling Protocol

2049

TCP + UDP

nfs

NFS

Network File System

6000 - 6063

TCP

x11

X11

X Window System


 


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