subscribe
Listen to one or more MQTT topic filters and print received messages.
Synopsis
mqattack subscribe [OPTIONS] -t <TOPIC>...
Options
| Flag | Default | Description |
|---|---|---|
-t, --topic <TOPIC> | (required) | Topic filter, repeatable |
-q, --qos <QOS> | 0 | QoS level: 0, 1, or 2 |
-C, --count <N> | (unlimited) | Exit after receiving N messages |
--hex | off | Print payload bytes as hexadecimal |
Multiple -t flags can be combined to subscribe to several filters in one
connection.
Output format
Each received message is printed on one line:
[2026-10-25 14:32:01] home/sensors/temp -> 22.4
With --hex:
[2026-10-25 14:32:01] home/sensors/temp -> 32 32 2e 34
Examples
Subscribe to all topics
mqattack subscribe -H 192.168.1.10 -t '#'
Multiple topic filters, exit after 5 messages
mqattack subscribe -H 192.168.1.10 -t 'home/#' -t 'sensors/#' -C 5
Authenticated subscription
mqattack subscribe -H 192.168.1.10 -u admin -P secret -t '#'
TLS with system root CAs
mqattack subscribe --tls -H broker.example.com -p 8883 -t '#'
TLS with a custom CA
mqattack subscribe --cafile ca.crt -H broker.example.com -p 8883 -t '#'
mTLS (client certificate)
mqattack subscribe \
--cafile ca.crt --cert client.crt --key client.key \
-H broker.example.com -p 8883 -t '#'
JWT authentication over TLS
mqattack subscribe --tls --jwt 'eyJhbGci...' \
-H broker.example.com -p 8883 -t '#'
Inspect binary payloads as hex
mqattack subscribe -H 192.168.1.10 -t 'device/raw' --hex
Capture a fixed number of messages for offline analysis
mqattack subscribe -H 192.168.1.10 -t '#' -C 100 > capture.txt