Messaging and IoT port numbers: mqtt, amqp, coap and xmpp

By Liam CooperOctober 27, 2026IANA registry as updated October 26, 2026

The registry assigns mqtt to port 1883 and secure-mqtt to 8883, amqp to 5672 and amqps to 5671, coap to 5683 and coaps to 5684, and xmpp-client and xmpp-server to 5222 and 5269. Eleven of the 20 entries in the table below carry a registration date, so the order in which they arrived can be read from the file.

This article also covers the device and building-automation protocols that sit nearby in the registry, from Modbus on 502 to BACnet on 47808.

Messaging and device entries

The earliest recorded date in this table is January 2006, for amqp on 5672; the latest is December 20, 2022, for dnp on 20000. The TLS form of MQTT is the odd one out: secure-mqtt on 8883 carries a registration date of February 27, 2008, while mqtt on 1883 has no date, only a modification on February 10, 2015.

amqp on 5672 is assigned on TCP, UDP and SCTP, making it one of the 88 numbers with an SCTP entry. dnp on 20000, registered December 20, 2022, is another. The XMPP numbers 5222 and 5269 are assigned on TCP only, with UDP held as reserved.

The TLS forms in this group were not always registered at the same time as the plain names. amqps on 5671 is dated March 26, 2008, more than two years after amqp on 5672 (January 2006); coaps followed coap by about two years. The XMPP group gained a third number later: after the client and server numbers, xmpp-bosh on 5280, “Bidirectional-streams Over Synchronous HTTP”, was added on November 25, 2009, on TCP only. The numbers between 5222 and 5269 belong to other services, such as hpvirtgrp on 5223.

Across the 20 entries in the table, 5 are assigned on TCP only (opcua-tcp, xmpp-client, xmpp-server, xmpp-bosh and ircs-u), and 2 carry an SCTP entry; the rest hold both TCP and UDP.

Specifications cited

CoAP shows how references accumulate. coap on 5683 cites RFC 7252 and RFC 8323; coaps on 5684 adds RFC 7301, the TLS application-layer protocol negotiation extension. The two XMPP entries both cite RFC 6120. The MQTT and AMQP entries cite no RFC.

The two MQTT entries were last changed within a month of each other: mqtt on February 10, 2015 and secure-mqtt on March 6, 2015. They sit 7,000 numbers apart, in different range pages.

Industrial and building protocols

Field-bus and building protocols take up a handful of entries, several with the same pattern of a plain and a TLS number. mbap, the “Modbus Application Protocol”, holds 502 with no date; its TLS form mbap-s on 802 was registered on June 10, 2014 and is one of only 20 System Ports with a recorded date. OPC UA splits 4840 by transport, opcua-tcp on TCP and opcua-udp on UDP, and registers opcua-tls on 4843; all three were last modified in 2018 or 2017.

bacnet on 47808 (“Building Automation and Control Networks”) dates from February 10, 2011. iec-104 on 2404 carries the full standard number in its label, “IEC 60870-5-104 process control over IP”. Three PROFInet entries, profinet-rt, profinet-rtm and profinet-cm, sit together on 34962 to 34964, all registered in November 2004. On 2222 and 44818 the registry keeps two spellings each for EtherNet/IP, one with a slash that breaks the current naming rules.

Discovery

Two local discovery protocols hold numbers in this area. mdns on 5353 cites RFC 6762, “Multicast DNS” (February 2013). ssdp on 1900 has no reference and no date. Both are assigned on TCP and UDP.

Chat

irc holds 194 on TCP and UDP. The registry also lists ircu as a range, 6665 to 6669 on TCP, and ircs-u on 6697 (registered February 11, 2014), which cites RFC 7194, “Default Port for Internet Relay Chat (IRC) via TLS/SSL”.

Numbers with no messaging entry

4222 and 61613 have no assignment in the registry, and 9092 is assigned to XmlIpcRegSvc, “Xml-Ipc Server Reg”, registered in January 2006. The lookup shows each of these with its nearest assigned neighbors.

For a wider search, try mqtt or coap in the lookup, or open ports 5000–5999, which holds the AMQP, CoAP and XMPP numbers within a few hundred places of each other.