NET-MQTT-TRACE(1)

💅 NET-MQTT-TRACE 💅

okay so bestie, this is net-mqtt-trace — a Perl script for decoding MQTT messages from IP packets, living its best life in the User Contributed Perl Documentation section. iykyk 🫶

✨ VERSION ✨

version 1.163170 — yes she has a version number and yes she's proud of it 🎀

🌸 SYNOPSIS 🌸

net-mqtt-trace [options] {dev|dumpfile}

# live decode
# decode MQTT packets that are visible on the interface eth0
net-mqtt-trace eth0

# batch decode
# sniff 100 MQTT packets from eth0 and write them to mqtt.tcp
# then later decode MQTT messages from tcpdump file
tcpdump -w mqtt.tcp -i eth0 -c 100 -s 4096 tcp and port 1883
net-mqtt-trace mqtt.tcp

like, two whole moods: sniffs it live off an interface, or reads a tcpdump file later. both iconic ✨

🦋 DESCRIPTION 🦋

so this script is literally an MQTT message decoder for IP packets, no cap. you can decode packets live by sniffing traffic on a network interface, or you can batch process them by reading them out of a tcpdump file. both are valid, both slay 💖

👑 OPTIONS 👑

• -help — prints a brief help message. the "hi, what do you need" of flags 🌈
• -man — prints the manual page. very meta, very main character 💅
• -verbose — gives you more verbose output. by default you only get a little output at the start and end of processing, but this turns on extra stuff — including a summary of the counts of the different packets decoded. the tea ☕
• -quiet — removes even the basic verbose output. she is silence, she is peace 🙈
• -link — prints link layer info (assumed to be Ethernet). you can repeat this option to get further output. repeat for more, periodt 🔥
• -ip — prints ip layer information. also repeatable for further output ✨
• -tcp — prints TCP layer information. repeatable too, bestie 🎀
• -mqtt — prints MQTT message information. guess what — also repeatable for further output 🦋
• -count NNN — stops processing after the given number of packets. default is to process all the packets, which is lowkey a lot 😭
• -snaplen NNN — maximum length of data to capture for each packet. default is 65535. ngl this one only gets used when you're capturing directly from a device 💀
• -promisc — turns on promiscuous mode. default is off. again, only used when capturing directly from a device 👀
• -timeout NNN — the read timeout in milliseconds. default is 0 (aka no timeout). and yes, only used when capturing directly from a device 🌸

⭐ SEE ALSO ⭐

Net::MQTT::Message(3), Net::Pcap(3), tcpdump(8) — go read these, they're the supporting cast and they ate 💜

💖 AUTHOR 💖

Mark Hindess <soft-cpan@temporalanomaly.com> — the icon who made this happen 🫶

🍓 COPYRIGHT AND LICENSE 🍓

This software is copyright (c) 2014 by Mark Hindess.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. slay, free software fr fr 💅

and that's the whole vibe check, bestie — page brought to you by perl v5.42.2, dated 2026-02-15, from the NET-MQTT-TRACE(1) manual. mwah 💋✨