603:
as RFC 433 in
December 1972 and included a list of hosts and their port numbers and the corresponding function used at each host in the network. This first registry function served primarily as documentation of usage and indicated that port number usage was conflicting between some hosts for "useful public services". The document promised a resolution of the conflicts based on a standard that Postel had published in May 1972 in RFC 349, in which he first proposed official assignments of port numbers to network services and suggested a dedicated administrative function, which he called a
99:, and the type of transport protocol used for communication. It completes the destination or origination address of a message. Specific port numbers are reserved to identify specific services so that an arriving packet can be easily forwarded to a running application. For this purpose, port numbers lower than 1024 identify the historically most commonly used services and are called the
187:(IANA). In many operating systems special privileges are required for applications to bind to these ports because these are often deemed critical to the operation of IP networks. Conversely, the client end of a connection typically uses a high port number allocated for short-term use, therefore called an
602:
called for documenting the then-current usages and establishing a socket number catalog in RFC 322. Network administrators were asked to submit a note or place a phone call, "describing the function and socket numbers of network service programs at each HOST". This catalog was subsequently published
535:
While the listening port number of a server is well defined (IANA calls these the well-known ports), the client's port number is often chosen from the dynamic port range (see below). In some applications, the clients and the server each use specific port numbers assigned by the IANA. A good example
580:
in the early development stages of the network. A socket number for a remote host was a 40-bit quantity. The first 32 bits were similar to today's IPv4 address, but at the time the most-significant 8 bits were the host number. The least-significant portion of the socket number (bits 33 through 40)
531:
applications on users' personal computers to fetch email messages from the server. The POP service listens on TCP port number 110. Both services may be running on the same host computer, in which case the port number distinguishes the service that was requested by a remote computer, be it a user's
179:, and involves the receipt of a request on the well-known port potentially establishing a one-to-one server-client dialog, using this listening port. Other clients may simultaneously connect to the same listening port; this works because a TCP connection is identified by a
159:. A socket is used by a process to send and receive data via the network. The operating system's networking software has the task of transmitting outgoing data from all application ports onto the network, and forwarding arriving
205:
IANA is responsible for the global coordination of the DNS root, IP addressing, and other protocol resources. This includes the registration of commonly used TCP and UDP port numbers for well-known internet services.
126:
For TCP and UDP, a port number is a 16-bit unsigned integer, thus ranging from 0 to 65535. For TCP, port number 0 is reserved and cannot be used, while for UDP, the source port is optional and a value of zero means
163:
to processes by matching the packet's IP address and port number to a socket. For TCP, only one process may bind to a specific IP address and port combination. Common application failures, sometimes called
499:
attempts or with network administrators looking for possible vulnerabilities to help prevent such attacks. Port connection attempts are frequently monitored and logged by hosts. The technique of
515:. A server used for sending and receiving email generally needs two services. The first service is used to transport email to and from other servers. This is accomplished with the
475:, and they can be readily interpreted not only by the sending and receiving hosts but also by other components of the networking infrastructure. In particular,
183:
consisting of the local address, the local port, the remote address, and the remote port. The well-known ports are defined by convention overseen by the
738:
is still closely connected with port numbers, the former being text strings used in some network functions to represent a numerical port number.
56:
is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service. At the software level, within an
799:
Internet
Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry
318:
232:) are those numbered from 0 through 1023. The requirements for new assignments in this range are stricter than for other registrations.
184:
731:
387:
519:(SMTP). A standard SMTP service application listens on TCP port 25 for incoming requests. The second service is usually either the
524:
376:
200:
834:
803:
429:
The registered ports are those from 1024 through 49151. IANA maintains the official list of well-known and registered ranges.
354:
72:
and address combination by the port number assigned to it. The most common transport protocols that use port numbers are the
516:
460:
448:
296:
73:
1062:
1057:
329:
471:
field for indicating the source and destination port numbers. The port numbers are encoded in the transport protocol
168:, occur when multiple programs attempt to use the same port number on the same IP address with the same protocol.
118:
of application architecture, multiple simultaneous communication sessions may be initiated for the same service.
591:
refers to a related but distinct concept, namely the internal address of an endpoint used only within the node.
549:
444:
31:
115:
661:
service received the first official assignment of the value 1. In detail, the first set of assignments was:
491:
The practice of attempting to connect to a range of ports in sequence on a single host is commonly known as
479:
are commonly configured to differentiate between packets based on their source or destination port numbers.
172:
100:
452:
263:
252:
77:
476:
365:
38:
432:
The dynamic or private ports are those from 49152 through 65535. One common use for this range is for
1007:
973:
936:
902:
865:
817:
772:
520:
343:
398:
132:
61:
503:
uses a series of port connections (knocks) from a client computer to enable a server connection.
468:
456:
307:
144:
69:
114:
service for multiple services or multiple communication sessions at one network address. In the
496:
997:
963:
926:
892:
855:
807:
762:
666:
607:, to maintain a registry. The 256 values of the AEN were divided into the following ranges:
57:
45:
480:
148:
140:
136:
88:
81:
65:
587:
433:
333:
188:
160:
104:
103:. Higher-numbered ports are available for general use by applications and are known as
92:
734:(NCP). NCP was the forerunner of the modern Internet protocols. Today the terminology
1051:
500:
492:
472:
540:
in which the client always uses UDP port 68 and the server always uses UDP port 67.
528:
274:
111:
820:
797:
572:
in informal cooperation of software authors and system administrators. The term
557:
409:
1010:
991:
976:
957:
939:
920:
905:
886:
775:
756:
670:
868:
849:
730:, and was used with the Initial Connection Protocol (ICP), a component of the
599:
552:(URLs). By default, HTTP uses port 80 and HTTPS uses port 443, but a URL like
152:
96:
595:
30:
This article is about software communication ports. For physical ports, see
568:
The concept of port numbers was established by the early developers of the
171:
Applications implementing common services often use specifically reserved
464:
17:
569:
37:"port (network)" redirects here. For ports in electrical networks, see
175:
for receiving service requests from clients. This process is known as
1002:
968:
931:
897:
860:
812:
767:
658:
420:
285:
512:
180:
537:
576:
was not yet in use. It was preceded by the use of the term
60:, a port is a logical construct that identifies a specific
796:
Michelle Cotton; Lars Eggert; et al. (August 2011).
68:. A port at the software level is identified for each
209:
The port numbers are divided into three ranges: the
495:. This is usually associated either with malicious
560:connects instead to port 8080 of the HTTP server.
511:An example of the use of ports is the delivery of
726:In the early ARPANET, the AEN was also called a
548:Port numbers are sometimes seen in web or other
288:remote login service, unencrypted text messages
135:associates its input or output channels via an
27:Communications endpoint in an operating system
1040:. Menlo Park, CA: Network Information Center.
837:. Internet Assigned Numbers Authority (IANA).
8:
885:Postel, J.; Neigus, N. (22 December 1972).
990:Shoshani, A.; Harslem, E. (14 July 1971).
87:A port number is always associated with a
1001:
967:
930:
896:
859:
811:
766:
951:
949:
880:
878:
663:
609:
234:
747:
919:Cerf, V.; Postel, J. (26 March 1972).
155:, and a port number. This is known as
993:Initial Connection Protocol--Reviewed
80:(UDP); those port numbers are 16-bit
7:
228:The well-known ports (also known as
483:is an example application of this.
319:Dynamic Host Configuration Protocol
185:Internet Assigned Numbers Authority
388:Simple Network Management Protocol
379:(IMAP) Management of digital mail
25:
1036:Postel, Jon; Feinler, E. (1978).
554:http://www.example.com:8080/path/
532:computer or another mail server.
959:Proposed Standard Socket Numbers
627:Network-wide standard functions
525:Internet Message Access Protocol
377:Internet Message Access Protocol
236:Notable well-known port numbers
201:List of TCP and UDP port numbers
459:(PDUs). For TCP, the PDU is a
355:Network News Transfer Protocol
1:
848:Crocker, S. (16 March 1970).
517:Simple Mail Transfer Protocol
449:Transmission Control Protocol
297:Simple Mail Transfer Protocol
74:Transmission Control Protocol
455:(UDP), transfer data using
330:Hypertext Transfer Protocol
1079:
956:Postel, J. (30 May 1972).
758:Transport Control Protocol
651:Any experimental function
585:, abbreviated AEN. Today,
412:(HTTPS) HTTP over TLS/SSL
198:
36:
29:
1038:ARPANET Protocol Handbook
1025:ARPANET Protocol Handbook
922:Well Known Socket Numbers
716:
708:
700:
692:
684:
679:
676:
647:
639:
631:
623:
618:
615:
550:uniform resource locators
445:Transport-layer protocols
416:
405:
394:
383:
372:
361:
350:
339:
325:
314:
303:
292:
281:
270:
259:
248:
243:
240:
732:Network Control Protocol
643:Reserved for future use
635:Host-specific functions
527:(IMAP) which is used by
32:Computer port (hardware)
583:Another Eightbit Number
467:. Both protocols use a
173:well-known port numbers
101:well-known port numbers
463:, and for UDP it is a
453:User Datagram Protocol
299:(SMTP) email delivery
266:(FTP) Command Control
264:File Transfer Protocol
253:File Transfer Protocol
78:User Datagram Protocol
581:was an entity called
423:IPv6 version of DHCP
366:Network Time Protocol
139:, which is a type of
39:Port (circuit theory)
665:Port assignments in
521:Post Office Protocol
344:Post Office Protocol
255:(FTP) Data Transfer
143:, associated with a
673:
612:
594:On March 26, 1972,
556:specifies that the
457:protocol data units
399:Internet Relay Chat
332:(HTTP) used in the
277:(SSH) Secure Login
237:
195:Common port numbers
116:client–server model
46:computer networking
1063:1972 introductions
1058:Internet protocols
888:Socket number list
664:
616:Port number range
610:
308:Domain Name System
235:
145:transport protocol
70:transport protocol
724:
723:
704:Remote job entry
655:
654:
427:
426:
16:(Redirected from
1070:
1042:
1041:
1033:
1027:
1021:
1015:
1014:
1005:
1003:10.17487/RFC0197
987:
981:
980:
971:
969:10.17487/RFC0349
953:
944:
943:
934:
932:10.17487/RFC0322
916:
910:
909:
900:
898:10.17487/RFC0433
882:
873:
872:
863:
861:10.17487/RFC0036
845:
839:
838:
831:
825:
824:
815:
813:10.17487/RFC6335
793:
787:
786:
784:
782:
770:
768:10.17487/RFC0793
752:
674:
648:240 through 255
640:128 through 239
613:
555:
440:Network behavior
238:
215:registered ports
211:well-known ports
110:Ports provide a
82:unsigned numbers
58:operating system
21:
1078:
1077:
1073:
1072:
1071:
1069:
1068:
1067:
1048:
1047:
1046:
1045:
1035:
1034:
1030:
1022:
1018:
989:
988:
984:
955:
954:
947:
918:
917:
913:
884:
883:
876:
847:
846:
842:
833:
832:
828:
816:. BCP 165.
795:
794:
790:
780:
778:
754:
753:
749:
744:
632:64 through 127
566:
553:
546:
509:
489:
481:Port forwarding
442:
434:ephemeral ports
203:
197:
161:network packets
149:network address
141:file descriptor
137:internet socket
124:
105:ephemeral ports
89:network address
66:network service
42:
35:
28:
23:
22:
15:
12:
11:
5:
1076:
1074:
1066:
1065:
1060:
1050:
1049:
1044:
1043:
1028:
1016:
982:
945:
911:
874:
851:Protocol Notes
840:
835:"Port Numbers"
826:
788:
755:Postel, John.
746:
745:
743:
740:
722:
721:
718:
714:
713:
710:
706:
705:
702:
698:
697:
696:File transfer
694:
690:
689:
686:
682:
681:
678:
653:
652:
649:
645:
644:
641:
637:
636:
633:
629:
628:
625:
621:
620:
617:
588:network socket
565:
562:
545:
542:
508:
505:
488:
485:
451:(TCP) and the
447:, such as the
441:
438:
425:
424:
418:
414:
413:
407:
403:
402:
396:
392:
391:
385:
381:
380:
374:
370:
369:
363:
359:
358:
352:
348:
347:
341:
337:
336:
334:World Wide Web
327:
323:
322:
316:
312:
311:
310:(DNS) service
305:
301:
300:
294:
290:
289:
283:
279:
278:
272:
268:
267:
261:
257:
256:
250:
246:
245:
242:
199:Main article:
196:
193:
189:ephemeral port
166:port conflicts
123:
120:
76:(TCP) and the
26:
24:
14:
13:
10:
9:
6:
4:
3:
2:
1075:
1064:
1061:
1059:
1056:
1055:
1053:
1039:
1032:
1029:
1026:
1020:
1017:
1012:
1009:
1004:
999:
995:
994:
986:
983:
978:
975:
970:
965:
961:
960:
952:
950:
946:
941:
938:
933:
928:
924:
923:
915:
912:
907:
904:
899:
894:
890:
889:
881:
879:
875:
870:
867:
862:
857:
853:
852:
844:
841:
836:
830:
827:
822:
819:
814:
809:
805:
801:
800:
792:
789:
777:
774:
769:
764:
760:
759:
751:
748:
741:
739:
737:
733:
729:
719:
715:
711:
707:
703:
699:
695:
691:
687:
683:
675:
672:
668:
662:
660:
650:
646:
642:
638:
634:
630:
626:
624:0 through 63
622:
614:
608:
606:
601:
597:
592:
590:
589:
584:
579:
578:socket number
575:
571:
563:
561:
559:
551:
543:
541:
539:
533:
530:
526:
523:(POP) or the
522:
518:
514:
506:
504:
502:
501:port knocking
498:
494:
493:port scanning
487:Port scanning
486:
484:
482:
478:
474:
473:packet header
470:
466:
462:
458:
454:
450:
446:
439:
437:
435:
430:
422:
419:
415:
411:
408:
404:
400:
397:
393:
389:
386:
382:
378:
375:
371:
367:
364:
360:
356:
353:
349:
345:
342:
338:
335:
331:
328:
324:
320:
317:
313:
309:
306:
302:
298:
295:
291:
287:
284:
280:
276:
273:
269:
265:
262:
258:
254:
251:
247:
239:
233:
231:
226:
224:
223:private ports
220:
216:
212:
207:
202:
194:
192:
190:
186:
182:
178:
174:
169:
167:
162:
158:
154:
150:
146:
142:
138:
134:
130:
121:
119:
117:
113:
108:
106:
102:
98:
95:, such as an
94:
90:
85:
83:
79:
75:
71:
67:
64:or a type of
63:
59:
55:
51:
47:
40:
33:
19:
1037:
1031:
1024:
1019:
992:
985:
958:
921:
914:
887:
850:
843:
829:
798:
791:
779:. Retrieved
757:
750:
736:service name
735:
727:
725:
677:Port number
656:
604:
593:
586:
582:
577:
573:
567:
547:
534:
529:email client
510:
490:
443:
431:
428:
275:Secure Shell
230:system ports
229:
227:
222:
218:
214:
210:
208:
204:
176:
170:
165:
156:
128:
125:
112:multiplexing
109:
86:
53:
49:
43:
728:socket name
680:Assignment
619:Assignment
611:AEN ranges
574:port number
558:web browser
544:Use in URLs
536:of this is
410:HTTP Secure
244:Assignment
151:such as an
122:Port number
54:port number
1052:Categories
1023:NIC 7104,
742:References
600:Jon Postel
217:, and the
153:IP address
97:IP address
781:1 January
596:Vint Cerf
477:firewalls
417:546, 547
177:listening
720:Discard
507:Examples
497:cracking
465:datagram
18:TCP Port
688:Telnet
570:ARPANET
564:History
461:segment
390:(SNMP)
357:(NNTP)
346:(POP3)
321:(DHCP)
315:67, 68
241:Number
219:dynamic
157:binding
133:process
129:no port
62:process
669:
659:Telnet
469:header
421:DHCPv6
401:(IRC)
368:(NTP)
286:Telnet
213:, the
712:Echo
513:email
181:tuple
91:of a
821:6335
804:IETF
783:2023
657:The
605:czar
598:and
538:DHCP
406:443
395:194
384:161
373:143
362:123
351:119
340:110
147:, a
131:. A
93:host
50:port
48:, a
1011:197
1008:RFC
998:doi
977:349
974:RFC
964:doi
940:322
937:RFC
927:doi
906:433
903:RFC
893:doi
866:RFC
856:doi
818:RFC
808:doi
776:793
773:RFC
763:doi
671:349
667:RFC
326:80
304:53
293:25
282:23
271:22
260:21
249:20
221:or
52:or
44:In
1054::
1006:.
996:.
972:.
962:.
948:^
935:.
925:.
901:.
891:.
877:^
869:36
864:.
854:.
806:.
802:.
771:.
761:.
717:9
709:7
701:5
693:3
685:1
436:.
225:.
191:.
107:.
84:.
1013:.
1000::
979:.
966::
942:.
929::
908:.
895::
871:.
858::
823:.
810::
785:.
765::
41:.
34:.
20:)
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