MOSQUITTO(8) Mosquitto MOSQUITTO(8) (NAME) mosquitto - MQTT (SYNOPSIS) mosquitto [-c ] [-d | --aemon] [-p ] [-q] [-v] [--ls-keylog ] (DESCRIPTION) mosquitto (broker) MQTT 5.0/3.1.1/3.1 . mosquitto . mosquitto(7) . (OPTIONS) -c, --onfig-file . 1883 (loopback) mosquitto.conf(5) . -p 1.6.x 2.0 . -d, --aemon mosquitto (daemon). . -p, --ort () . . 1.6.x -p ( 1883) . -c . 2.0 -p (loopback) . -p -p . -q, --quiet 2.1 . (). log_type none . -- . --est-config 2.1 . -c . 0 . --ls-keylog file 2.1 . TLS file. tcpdump, wireshark mqttshark TLS MQTT . Wireshark (Pre)-Master-Secret log filename Transport Layer Security . . -v, -- (verbose). log_type all . . (CONFIGURATION) mosquitto.conf(5) mosquitto . SSL/TLS mosquitto-tls(7) . (PLATFORM LIMITATIONS) API . Windows 10 Windows Server 2019 . . MQTT (MQTT SUPPORT) Mosquitto v5.0 v3.1.1 v3.1 MQTT . MQTT v5.0 Mosquitto MQTT v5.0 . Mosquitto . (Features) Enhanced authentication ( ) MQTT / . MQTT . . Mosquitto (plugins) . Error handling ( ) MQTT (reason code) . Mosquitto (reason string) . Flow control ( ) << >> (in flight) QoS 1 QoS 2 . Request / response ( / ) MQTT v5.0 / . Server redirection ( ) MQTT CONNECT DISCONNECT . Mosquitto . Shared subscriptions ( ) . (Packet properties) MQTT v5.0 . Mosquitto . CONNECT o Authentication data ( ) o Authentication method ( ) o Maximum packet size ( ) o Receive maximum ( ) o Request problem information - o Request response information - o Session expiry interval ( ) o Topic alias maximum ( ) o User property ( ) Last will and testament ( ) o Content type ( ) o Correlation data ( ) o Message expiry interval ( ) o Payload format indicator ( ) o Response topic ( ) o User property ( ) o Will delay interval ( ) CONNACK o Assigned client identifier ( ) o Authentication data ( ) o Authentication method ( ) o Maximum packet size ( ) o Maximum qos ( qos) o Reason string - o Receive maximum ( ) o Response information - o Retain available ( ) o Server keep alive ( ) o Server reference - o Session expiry interval ( ) o Shared subscription available ( ) o Subscription identifiers available ( ) o Topic alias maximum ( ) o User property ( ) o Wildcard subscription available ( ) PUBLISH o Content type ( ) o Correlation data ( ) o Message expiry interval ( ) o Payload format indicator ( ) o Response topic ( ) o Subscription identifier ( ) o Topic alias ( ) o User property ( ) PUBACK / PUBREC / PUBREL / PUBCOMP / SUBACK / SUBSCRIBE / SUBACK o Reason string - o User property ( ) SUBSCRIBE o Subscription identifier ( ) o User property ( ) DISCONNECT o Reason string - o Server reference - o Session expiry interval ( ) o User property ( ) AUTH o Authentication method ( ) o Authentication data ( ) o Reason string - o User property ( ) MQTT v3.1.1 Mosquitto MQTT v3.1.1 . MQTT v3.1 Mosquitto MQTT v3.1 . MQTT v3 MQTT v3 / (clean start) CONNECT . MQTT v3 Mosquitto . (BROKER STATUS) $SYS . (static) . sys_interval . sys_interval 0 . $SYS $ '$SYS/...' : \$SYS/... $SYS . $SYS/broker/bytes/received . $SYS/broker/bytes/sent . $SYS/broker/clients/connected, $SYS/broker/clients/active () . $SYS/broker/clients/expired persistent_client_expiration . $SYS/broker/clients/disconnected, $SYS/broker/clients/inactive () ( ) . $SYS/broker/clients/maximum . $SYS/broker/clients/total . $SYS/broker/connection/# (bridges) . $SYS/broker/connection/ . 1 0 . . $SYS/broker/connections/socket/count MQTT . $SYS/broker/heap/current (heap) mosquitto. . $SYS/broker/heap/maximum mosquitto. . $SYS/broker/load/connections/+ CONNECT . "+" 1min 5min 15min . . $SYS/broker/load/bytes/received/+ . "+" 1min 5min 15min . . $SYS/broker/load/bytes/sent/+ . "+" 1min 5min 15min . . $SYS/broker/load/messages/received/+ MQTT . "+" 1min 5min 15min . . $SYS/broker/load/messages/sent/+ MQTT . "+" 1min 5min 15min . . $SYS/broker/load/publish/dropped/+ (publish) . . "+" 1min 5min 15min . . $SYS/broker/load/publish/received/+ . "+" 1min 5min 15min . . $SYS/broker/load/publish/sent/+ . "+" 1min 5min 15min . . $SYS/broker/load/sockets/+ . "+" 1min 5min 15min . . $SYS/broker/messages/received . $SYS/broker/messages/sent . $SYS/broker/mqtt/connect/received MQTT CONNECT . $SYS/broker/mqtt/connack/sent MQTT CONNACK . $SYS/broker/mqtt/publish/dropped, $SYS/broker/publish/messages/dropped MQTT PUBLISH / . max_inflight_messages max_queued_messages mosquitto.conf(5) . $SYS/broker/mqtt/publish/received, $SYS/broker/publish/messages/received MQTT PUBLISH . $SYS/broker/mqtt/publish/sent, $SYS/broker/publish/messages/sent MQTT PUBLISH . $SYS/broker/mqtt/puback/received MQTT PUBACK . $SYS/broker/mqtt/puback/sent MQTT PUBACK . $SYS/broker/mqtt/pubrec/received MQTT PUBREC . $SYS/broker/mqtt/pubrec/sent MQTT PUBREC . $SYS/broker/mqtt/pubrel/received MQTT PUBREL . $SYS/broker/mqtt/pubrel/sent MQTT PUBREL . $SYS/broker/mqtt/pubcomp/received MQTT PUBCOMP . $SYS/broker/mqtt/pubcomp/sent MQTT PUBCOMP . $SYS/broker/mqtt/subscribe/received MQTT SUBSCRIBE . $SYS/broker/mqtt/suback/sent MQTT SUBACK . $SYS/broker/mqtt/unsubscribe/received MQTT UNSUBSCRIBE . $SYS/broker/mqtt/unsuback/sent MQTT UNSUBACK . $SYS/broker/mqtt/pingreq/received MQTT PINGREQ . $SYS/broker/mqtt/pingresp/sent MQTT PINGRESP . $SYS/broker/mqtt/disconnect/received MQTT DISCONNECT . $SYS/broker/mqtt/disconnect/sent MQTT DISCONNECT . $SYS/broker/mqtt/auth/received MQTT AUTH . $SYS/broker/mqtt/auth/sent MQTT AUTH . $SYS/broker/packet/out/count . . $SYS/broker/packet/out/bytes . . $SYS/broker/publish/bytes/received (payload) PUBLISH . $SYS/broker/publish/bytes/sent PUBLISH . $SYS/broker/retained messages/count (retained) . $SYS/broker/store/messages/count, $SYS/broker/messages/stored () . . $SYS/broker/store/messages/bytes . . $SYS/broker/shared_subscriptions/count . $SYS/broker/subscriptions/count . $SYS/broker/version . (Static). (WILDCARD TOPIC SUBSCRIPTIONS) mosquitto (wildcard) . + . "a/b/c/d" : o a/b/c/d o +/b/c/d o a/+/c/d o a/+/+/d o +/+/+/+ : o a/b/c o b/+/c/d o +/+/+ # . "a/b/c/d" : o a/b/c/d o # o a/# o a/b/# o a/b/c/# o +/b/c/# $SYS "#" . $SYS $SYS/# . "a/b+/c" . # . (BRIDGES) (bridging) . . . . . mosquitto.conf(5) . (SIGNALS) (POSIX) Mosquitto . : kill -HUP SIGHUP SIGHUP mosquitto -c mosquitto . . mosquitto.conf(5) . TLS mosquitto SIGHUP . . SIGRTMIN SIGRTMIN mosquitto (log rotation) . SIGUSR1 SIGUSR1 mosquitto . (persistence) . SIGUSR2 SIGUSR2 mosquitto (retained) . . (ENVIRONMENT VARIABLES) MOSQUITTO_UNSAFE_ALLOW_SYMLINKS (symlink) . . . (FILES) /etc/mosquitto/mosquitto.conf . mosquitto.conf(5). /var/lib/mosquitto/mosquitto.db . /etc/hosts.allow, /etc/hosts.deny tcp-wrappers hosts_access(5) . (BUGS) mosquitto : https://github.com/eclipse-mosquitto/mosquitto/issues (SEE ALSO) mosquitto(7), mqtt(7), mosquitto-tls(7), mosquitto.conf(5), mosquitto_ctrl(1), mosquitto_passwd(1), mosquitto_pub(1), mosquitto_rr(1), mosquitto_sub(1), libmosquitto(3) (THANKS) Andy Stanford-Clark MQTT . Andy Nicholas O'Leary . Ubuntu UK Podcast Linux Outlaws OggCamp Andy mosquitto . (AUTHOR) Roger Light Mosquitto Project 04/03/2026 MOSQUITTO(8)