# AMQP ## Overview **AMQP** (Advanced Message Queuing Protocol) is an open, binary wire-level messaging protocol, originally developed at JPMorgan Chase and later standardized by OASIS and ISO/IEC. It runs over **TCP**, on IANA-assigned port **5672** for cleartext traffic and **5671** for TLS-secured **AMQPS**, with SASL negotiation on 5672 also able to upgrade a connection to TLS in place. AMQP is broker-centric messaging middleware: producers publish messages to a broker (RabbitMQ, ActiveMQ, Azure Service Bus, etc.) that routes them via exchanges and queues (0-9-1) or link/node addressing (1.0) to consumers, making it common in enterprise messaging, IoT telemetry, and financial transaction systems. Two incompatible wire formats circulate under the same protocol name and are readily distinguished on the wire: both open a connection with the fixed 8-byte ASCII preamble **`AMQP`** followed by a protocol-ID byte and three version bytes — `41 4D 51 50 00 00 09 01` for **AMQP 0-9-1** (the format used by RabbitMQ) versus `41 4D 51 50 00 01 00 00` for **AMQP 1.0** (the OASIS/ISO standard) — giving a reliable version fingerprint independent of payload. Traffic is cleartext by default unless the AMQPS/TLS variant or a SASL security layer is negotiated, and frames carry broker-, exchange-, and queue-name strings in plaintext that can further identify the messaging backend in use. ### General Frame Format 0 12 36 7size+6 size+7 typeoctet channelshort sizelong payload'size' octets frame-endoctet AMQP defines these frame types: Type Name Description 1 METHOD Method frame. 2 HEADER Content header frame. 3 BODY Content body frame. 4 HEARTBEAT Heartbeat frame. ### Method Payloads 0 2 4 class-idshort method-idshort arguments...... ### Property and Method Summary #### connection (Class ID 10) Method ID Description Method ID Description start10start connection negotiation tune-ok31negotiate connection tuning parameters start-ok11select security mechanism and locale open40open connection to virtual host secure20security mechanism challenge open-ok41signal that connection is ready secure-ok21security mechanism response close50request a connection close tune30propose connection tuning parameters close-ok51confirm a connection close #### channel (Class ID 20) Method ID Description Method ID Description open10open a channel for use flow-ok21confirm a flow method open-ok11signal that the channel is ready close40request a channel close flow20enable/disable flow from peer close-ok41confirm a channel close #### exchange (Class ID 40) Method ID Description Method ID Description declare10verify exchange exists, create if needed delete20delete an exchange declare-ok11confirm exchange declaration delete-ok21confirm deletion of an exchange #### queue (Class ID 50) Method ID Description Method ID Description declare10declare queue, create if needed purge-ok31confirms a queue purge declare-ok11confirms a queue definition delete40delete a queue bind20bind queue to an exchange delete-ok41confirm deletion of a queue bind-ok21confirm bind successful unbind50unbind a queue from an exchange purge30purge a queue unbind-ok51confirm unbind successful #### basic (Class ID 60) Method ID Description Method ID Description qos10specify quality of service get70direct access to a queue qos-ok11confirm the requested qos get-ok71provide client with a message consume20start a queue consumer get-empty72indicate no messages available consume-ok21confirm a new consumer ack80acknowledge one or more messages cancel30end a queue consumer reject90reject an incoming message cancel-ok31confirm a cancelled consumer recover-async100redeliver unacknowledged messages publish40publish a message recover110redeliver unacknowledged messages return50return a failed message recover-ok111confirm recovery deliver60notify the client of a consumer message #### tx (Class ID 90) Method ID Description Method ID Description select10select standard transaction mode commit-ok21confirm a successful commit select-ok11confirm transaction mode rollback30abandon the current transaction commit20commit the current transaction rollback-ok31confirm successful rollback ### Sample Hexdump Protocol Header. The client MUST start a new connection by sending a protocol header. This is an 8-octet sequence: ``` Advanced Message Queuing Protocol Type: Method (1) Channel: 0 Length: 524 Class: Connection (10) Method: Start (10) Arguments 0000 41 4d 51 50 00 00 09 01 AMQP.... ``` Connection.Open ``` Advanced Message Queuing Protocol Type: Method (1) Channel: 0 Length: 8 Class: Connection (10) Method: Open (40) Arguments Virtual-Host: / Capabilities: .... ...1 = Insist: True 0000 01 00 00 00 00 00 08 00 0a 00 28 01 2f 00 01 ce ..........(./... ``` ### Reference [AMQP Wireshark Wiki](https://wiki.wireshark.org/AMQP) [IANA search=amqp](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=amqp) [RabbitMQ: Inspecting AMQP 0-9-1 Traffic using Wireshark](https://www.rabbitmq.com/amqp-wireshark) [amqp-specification.zip](https://github.com/ericwu1997/ericwu1997.github.io/raw/refs/heads/main/content/docs/app-layer-protocols/amqp/amqp-specification.zip)