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List of TCP Ports and UDP Ports (Well-Known) 2021

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The Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) each use port numbers for their communication channels. The ports numbered 0 through 1023 are the well-known system ports, reserved for special uses. 

Port 0 is not used for TCP/UDP communication although it used as a network programming construct. 

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The Breakdown of Other System Ports

(TCP) TCPMUX - TCP Port Service Multiplexer. Allows any of multiple TCP services to be contacted by their service name. See RFC 1078.(TCP) Management Utility. Formerly used by the Compressnet product, for compression of TCP WAN traffic.(TCP) Compression Process. Formerly used by Compressent for compression of TCP WAN traffic.(TCP/UDP) Unassigned(TCP/UDP) Remote Job Entry. Mechanism for executing batch jobs remotely. See RFC 407.(TCP/UDP) Unassigned(TCP/UDP) Echo. When enabled for debugging purposes, returns to the source any data received. See RFC 862.(TCP/UDP) Unassigned(TCP/UDP) Discard. When enabled for debugging purposes, throws away any data received with no response sent. See RFC 86.(TCP/UDP) Unassigned(TCP) Active Users. Unix TCP systat. See RFC 866.(TCP/UDP) Unassigned(TCP/UDP) Daytime. See RFC 867.(TCP/UDP) Unassigned(TCP/UDP) Unassigned. Formerly reserved for Unix netstat.(TCP/UDP) Unassigned.(TCP/UDP) Quote of the Day. For Unix qotd. See RFC 865.(TCP) Message Send Protocol (formerly) and Remote Write Protocol. (UDP) Remote Wire Protocol. See RFC 1312 and RFC 1756.(TCP/UDP) Character Generator Protocol. See RFC 864.(TCP) File Transfer. For FTP data.(TCP) File Transfer. For FTP control.(TCP) SSH Remote Login Protocol. (UDP) pcAnywhere.(TCP) Telnet(TCP/UDP) For private mail systems.(TCP) Simple Mail Transfer Protocol (SMTP). See RFC 821.(TCP/UDP) Unassigned(TCP/UDP) ESMTP. POP mail service of SLMail.(TCP/UDP) Unassigned(TCP/UDP) MSG ICP.(TCP/UDP) Unassigned(TCP/UDP) MSG Authentication(TCP/UDP) Unassigned(TCP/UDP) Display Support Protocol(TCP/UDP) Unassigned(TCP/UDP) For private printer servers.(TCP/UDP) Unassigned(TCP/UDP) Time Protocol. See RFC 868.(TCP/UDP) Route Access Protocol (RAP). See RFC 1476.(UDP) Resource Location Protocol. See RFC 887.(TCP/UDP) Unassigned(TCP/UDP) Graphics(UDP) Host Name Server - Microsoft WINS(TCP) WHOIS. Also known as NICNAME. RFC 954.(TCP) MPM FLAGS Protocol(TCP) Message Processing Module (receive)(TCP) Message Processing Module (send)(TCP/UDP) NI FTP(TCP/UDP) Digital Audit Daemon(TCP) Login Host Protocol. Also known as TACACS. See RFC 927 and RFC 1492.(TCP/UDP) Remote Mail Checking Protocol (RMCP). See RFC 1339.(TCP/UDP) IMP Logical Address Maintenance(TCP/UDP) XNS Time Protocol(TCP/UDP) Domain Name Server (DNS)(TCP/UDP) XNS Clearinghouse(TCP/UDP) ISI Graphics Language(TCP/UDP) XNS Authentication(TCP/UDP) private terminal access. For example, TCP Mail Transfer Protocol (MTP). See RFC 772 and RFC 780.(TCP/UDP) XNS Mail(TCP/UDP) private file services. For example, NFILE. See RFC 1037.(TCP/UDP) Unassigned(TCP/UDP) NI Mail(TCP/UDP) ACA Services(TCP/UDP) Whois and Network Information Lookup Service. Also known as Whois++. See RFC 1834.(TCP/UDP) Communications Integrator(TCP/UDP) TACACS Database Service(TCP/UDP) Oracle SQL*NET(TCP/UDP) Bootstrap Protocol Server. (UDP) Unofficially, Dynamic Host Configuration Protocol (DHCP) servers use this port.(TCP/UDP) Bootstrap Protocol Client (BOOTP). See RFC 951. (UDP) Unofficially, DHCP clients use this port.(TCP/UDP) Trivial File Transfer Protocol (TFTP). See RFC 906 and RFC 1350.(TCP/UDP) Gopher. See RFC 1436.(TCP/UDP) Remote Job Service(TCP/UDP) Remote Job Service(TCP/UDP) Remote Job Service(TCP/UDP) Remote Job Service(TCP/UDP) private dial-out services(TCP/UDP) Distributed External Object Store(TCP/UDP) private remote job execution services(TCP/UDP) Vettcp Service(TCP/UDP) Finger User Information Protocol. See RFC 1288.(TCP) Hypertext Transfer Protocol (HTTP). See RFC 2616.(TCP/UDP) HOSTS2 Name Server(TCP/UDP) XFER Utility(TCP/UDP) MIT ML Device(TCP/UDP) Common Trace Facility(TCP/UDP) MIT ML Device(TCP/UDP) Micro Focus COBOL(TCP/UDP) private terminal links(TCP/UDP) Kerberos Network Authentication Service. See RFC 1510.(TCP/UDP) SU/MIT Telnet Gateway(TCP/UDP) DNSIX Security Attribute Token Map(TCP/UDP) MIT Dover Spooler(TCP/UDP) Network Printing Protocol(TCP/UDP) Device Control Protocol(TCP/UDP) Tivoli Object Dispatcher(TCP/UDP) SUPDUP Display Protocol. See RFC 734.(TCP/UDP) DIXIE Protocol. See RFC 1249.(TCP/UDP) Swift Remote Virtual File Protocol(TCP/UDP) TAC News. Unofficially used today by Linux utility linuxconf.(TCP/UDP) Metagram Relay