TCP and UDP Port Assignments

Port Assignments for Well-Known Ports

The Well-Known Ports are assigned by the IANA.

Ports are used in TCP or UDP communications to name the ends of logical connections that transfer data. For the purpose of providing services to unknown clients, ports were created. Table C.1 specifies the port used by the server process as its contact port. The contact port is sometimes called a Well-Known Port.

The assigned ports use a small portion of the possible port numbers. For many years the assigned ports were in the range 0-255. The range for assigned ports managed by the IANA has been expanded to the range 0-1023. The list in Table C.1 contains most of the port assignments that are significant to the Windows 2000 operating system.

Table C.1 Well-Known Ports

Port No.	Protocol	Service Name	Aliases	Comment
7	TCP	echo		Echo
7	UDP	echo		Echo
9	TCP	discard	sink null	Discard
9	UDP	discard	sink null	Discard
13	TCP	daytime		Daytime
13	UDP	daytime		Daytime
17	TCP	qotd	quote	Quote of the day
17	UDP	qotd	quote	Quote of the day
19	TCP	chargen	ttytst source	Character generator
19	UDP	chargen	ttytst source	Character generator
20	TCP	ftp-data		File Transfer
21	TCP	ftp		FTP Control
23	TCP	telnet		Telnet
25	TCP	smtp	mail	Simple Mail Transfer
37	TCP	time		Time
37	UDP	time		Time
39	UDP	rlp	resource	Resource Location Protocol
42	TCP	nameserver	name	Host Name Server
42	UDP	nameserver	name	Host Name Server
43	TCP	nicname	whois	Who Is
53	TCP	domain		Domain Name
53	UDP	domain		Domain Name Server
67	UDP	bootps	dhcps	Bootstrap Protocol Server
68	UDP	bootpc	dhcpc	Bootstrap Protocol Client
69	UDP	tftp		Trivial File Transfer
70	TCP	gopher		Gopher
79	TCP	finger		Finger
80	TCP	http	www, http	World Wide Web
88	TCP	kerberos	krb5	Kerberos
88	UDP	kerberos	krb5	Kerberos
101	TCP	hostname	hostnames	NIC Host Name Server
102	TCP	iso-tsap		ISO-TSAP Class 0
107	TCP	rtelnet		Remote Telnet Service
109	TCP	pop2	postoffice	Post Office Protocol - Version 2
110	TCP	pop3	postoffice	Post Office Protocol - Version 3
111	TCP	sunrpc	rpcbind portmap	SUN Remote Procedure Call
111	UDP	sunrpc	rpcbind portmap	SUN Remote Procedure Call
113	TCP	auth	ident tap	Authentication Sevice
117	TCP	uucp-path		UUCP Path Service
119	TCP	nntp	usenet	Network News Transfer Protocol
123	UDP	ntp		Network Time Protocol
135	TCP	epmap	loc-srv	DCE endpoint resolution
135	UDP	epmap	loc-srv	DCE endpoint resolution
137	TCP	netbios-ns	nbname	NETBIOS Name Service
137	UDP	netbios-ns	nbname	NETBIOS Name Service
138	UDP	netbios-dgm	nbdatagram	NETBIOS Datagram Service
139	TCP	netbios-ssn	nbsession	NETBIOS Session Service
143	TCP	imap	imap4	Internet Message Access Protocol
158	TCP	pcmail-srv	repository	PC Mail Server
161	UDP	snmp	snmp	SNMP
162	UDP	snmptrap	snmp-trap	SNMP TRAP
170	TCP	print-srv		Network PostScript
179	TCP	bgp		Border Gateway Protocol
194	TCP	irc		Internet Relay Chat Protocol
213	UDP	ipx		IPX over IP
389	TCP	ldap		Lightweight Directory Access Protocol
443	TCP	https	MCom
443	UDP	https	MCom
445	TCP			Microsoft CIFS
445	UDP			Microsoft CIFS
464	TCP	kpasswd		Kerberos (v5)
464	UDP	kpasswd		Kerberos (v5)
500	UDP	isakmp	ike	Internet Key Exchange (IPSec)
512	TCP	exec		Remote Process Execution
512	UDP	biff	comsat	Notifies users of new mail
513	TCP	login		Remote Login
513	UDP	who	whod	Database of who's logged on, average load
514	TCP	cmd	shell	Automatic Authentication
514	UDP	syslog
515	TCP	printer	spooler	Listens for incoming connections
517	UDP	talk		Establishes TCP Connection
518	UDP	ntalk
520	TCP	efs		Extended File Name Server
520	UDP	router	router routed	RIPv.1, RIPv.2
525	UDP	timed	timeserver	Timeserver
526	TCP	tempo	newdate	Newdate
530	TCP,UDP	courier	rpc	RPC
531	TCP	conference	chat	IRC Chat
532	TCP	netnews	readnews	Readnews
533	UDP	netwall		For emergency broadcasts
540	TCP	uucp	uucpd	Uucpd
543	TCP	klogin		Kerberos login
544	TCP	kshell	krcmd	Kerberos remote shell
550	UDP	new-rwho	new-who	New-who
556	TCP	remotefs	rfs rfs_server	Rfs Server
560	UDP	rmonitor	rmonitord	Rmonitor
561	UDP	monitor
636	TCP	ldaps	sldap	LDAP over TLS/SSL
749	TCP	kerberos-adm		Kerberos administration
749	UDP	kerberos-adm		Kerberos administration