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Connect via RJ45 (traditional FTDI path)

For gear without USB-C console (most Cisco equipment from before ~2022), the traditional path is an RJ45 console port + USB-to-serial adapter cable.

What you need

  • Cable Matters USB to Cisco Console Cable — FTDI variant, 6 ft (or equivalent from Tripp Lite, StarTech, etc.)
  • Must specify FTDI FT232 chip (not Prolific PL2303 — the Prolific variant has driver quirks under Trixie)
  • The cable has an RJ45 connector on one end with rollover pinout built in

Physical connection

  • USB-A end into any USB port on the Pi
  • RJ45 end into the target's console port (usually blue, labeled CONSOLE)

What the Pi sees

The FTDI cable enumerates as a USB-serial adapter:

lsusb | grep -iE 'ftdi|future technology'
# Bus 001 Device 006: ID 0403:6001 Future Technology Devices International, Ltd FT232 Serial (UART) IC

And a /dev/ttyUSB* character device appears:

ls /dev/ttyUSB*
# /dev/ttyUSB0

Udev populates useful attributes:

udevadm info -q property /dev/ttyUSB0 | grep -E '^ID_'
# ID_VENDOR=FTDI
# ID_MODEL=FT232R_USB_UART
# ID_MODEL_ID=6001
# ID_SERIAL=FTDI_FT232R_USB_UART_ABC123XY
# ID_VENDOR_ID=0403

ser2net port mapping

ConsolePi's ser2net config maps /dev/ttyUSB* devices to telnet ports:

Device Telnet port
/dev/ttyUSB0 8001
/dev/ttyUSB1 8002
/dev/ttyUSB2 8003
/dev/ttyUSB3 8004
/dev/ttyUSB4 8005
/dev/ttyUSB5 8006
/dev/ttyUSB6 8007
/dev/ttyUSB7 8008

Talk to the device

From any host on your LAN:

telnet ConsolePi.local 8001

Hit Enter to elicit a prompt. Default baud rate is 9600, which is correct for virtually all Cisco console ports.

Exit telnet: Ctrl-] then quit.

Alternate: SSH + screen

ssh pi@ConsolePi.local
sudo screen /dev/ttyUSB0 9600

Exit screen: Ctrl-A then k (kill) or Ctrl-A then d (detach).

Baud rates for other vendors

Not every vendor uses 9600 for console. If you're consoling a non-Cisco device:

Vendor Common console baud
Cisco (most) 9600
Cisco UCS C-series server (BIOS/CIMC redirect) 115200
Juniper 9600
Arista 9600
Palo Alto 9600
Fortinet 9600
Dell PowerEdge iDRAC serial 115200
HPE ProLiant iLO serial 9600 or 115200 (check iLO config)

To use a different baud rate at connect time via ser2net, you'd need to add a custom port stanza in /etc/ser2net.yaml, or connect via screen /dev/ttyUSB0 115200 directly.

Multiple devices

Same as USB-C — 4 direct USB ports on the Pi, more via powered USB hub. The /dev/ttyUSB* device numbers are assigned in USB enumeration order, which can shift between reboots. For stable naming, use the udev-populated /dev/serial/by-id/ path or use consolepi-addconsole to create persistent aliases.

Watch out for

  • Rollover cable + straight-through RJ45 doesn't work. Cisco console needs rollover pinout, which is built into console cables specifically. A random RJ45 patch cable will not work in place of a console cable.
  • RJ45 console and USB console — on newer Cisco gear that has both, USB wins if both are plugged in. Unplug the USB-C side if you want to force the RJ45 console.
  • Prolific PL2303 cables are cheaper but have Linux driver quirks that manifest as intermittent character drops. Stick with FTDI.

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