The backpack kit is what you carry when you don't know what the day will need. Different from the lab bench, different from the travel router. This is the "go bag" — capable across compute, radio, NFC, USB, with a power budget that lasts the day. I refined it over about eighteen months of dragging different combinations to events, labs, and friends' apartments to debug their networks.
Tier 1 · Compute
Two Pis. The Pi 4 is the workhorse — Kali ARM64, 4GB, USB-C powered. It runs everything I need a real Linux machine for: Burp, Aircrack, Bettercap, Nmap. The Pi Zero 2 W is the drop device. It boots into P4wnP1 and is small enough to forget about, big enough to act as a HID, network bridge, or Bluetooth proxy when needed.
Both Pis live in a hard SSD case with foam cutouts so the SD cards don't shake loose. I lost three SD cards to vibration before I started using the case.
Tier 2 · Radio
The radio kit is where the kit earns its rent. Coverage spans 13.56 MHz (NFC) through 2.4 GHz (Wi-Fi/BLE/Zigbee/proprietary remotes), each with the right interface for the right job.
[ ESP32 MARAUDER + GPS ] wifi/ble recon, wardriving, deauth tests [ NRF24L01+ ] 2.4 GHz packet sniff, mousejack PoCs [ PN532 NFC SHIELD ] MIFARE Classic / NTAG / DESFire reads [ TP-LINK AC600 ] monitor mode + injection · external ant. [ HACKRF (BENCH ONLY) ] SDR experiments — too power-hungry for field
The TP-Link AC600 is the unsung hero. The Pi's built-in radio doesn't do monitor mode reliably and the antenna is anaemic. The AC600 with the right driver is rock solid for everything aircrack-ng wants to do.
Tier 3 · Power and cables
This tier is what makes or breaks the kit. The wrong cable in the wrong moment ends a day. I carry: USB-C PD powerbank (20Ah), short USB-C to USB-C, USB-C to USB-A, USB-A to micro, USB-A to mini, an OTG adapter, and a 40-pin GPIO ribbon for when the Pi has to talk to something weird. All cables are velcro-tied and labelled with shrink wrap.
Label every cable at both ends with the speed and capability (e.g. USB-C · PD · 100W vs USB-C · 2.0 · charge only). Cheap charge-only cables look identical to data cables and will silently waste hours of your life when you can't figure out why the Pi isn't enumerating.
What I removed and why
The kit used to include a full bash bunny, a flipper zero clone, a soldering iron, and a small multimeter. The reality is: I never used 80% of it in the field. The flipper duplicates what the PN532 + NRF24 already do. The soldering iron belongs at the bench. The multimeter only ever came out for two specific power-supply diagnoses that never happened on the road. They got cut.
The hardest thing to build is not the kit — it's the discipline to remove things from the kit. Every gram you carry is a gram you're still carrying when you don't need it.
The bag itself
Boring answer: a Peak Design 20L. The dividers are key. The hard SSD case for the Pis sits in one slot, the radio kit in a small zipped pouch, the cables in a roll. Nothing rattles, nothing migrates between compartments.