Adding a separate USB-Serial console to SG-2440 - /etc/ttys woes?

  • Running 2.4 Beta on official SG-2440 hardware.

    Netgate SG-2440 hardware comes with a built-in USB console for debugging.
    I'm trying to add a separate "physical" serial port console to the SG-2440, mainly for the purposes of "cheap" out of band debugging from devices that support physical serial redirect function, such as some Cradlepoint routers, SpiderDuo KVM (etc).
    I got a suggestion to try using an FTDI-based USB to serial adapter:
    When plugged into a SG-2440 USB port, pfSense "sees" it as a serial adapter /dev/cuaU0, and I can send and receive data by running "cu -l /dev/cuaU0 -s 9600" from pfSense command-line. So far so good.
    I added uftdi_load="yes" to /boot/loader.conf, and after a reboot I can send and receive data via /dev/ttyU0 by running "screen /dev/ttyU0 115200". Not sure editing /boot/loader.conf is necessary, but again it seems to work fine.

    Now I want to turn /dev/ttyU0 into a console port that I can use to access pfSense CLI.
    From what I've read (, this should be possible. However, any changes I make to the /etc/ttys file seem to be overwritten after boot.
    For instance, if I add the following to /etc/ttys:

    ttyU0  "/usr/libexec/getty Pc"  vt100  on    secure

    It gets overwritten with this on the next boot:

    ttyU0  "/usr/libexec/getty al.3wire"  vt100  onifconsole    secure

    At this point I'm still able to send/receive data on ttyU0 by connecting from pfSense command line, but this isn't what I want to do. I want to be able to access the physical serial end and have it be a command-line interface to pfSense.

    Am I going about this wrong? Is adding another serial console to the SG-2440 impossible to do, or does FreeBSD have issues with creating console ports out of serial-USB devices? Any thoughts or suggestions are appreciated.

  • Like you I wanted to have serial console for out of band management and I succeed to assign serial console to AMT instead of local COM port. The only disadvantage is that I lost local serial console from COM port…. not a big problem if computer have a VGA port.

    If you want to have other adapter assigned to serial console you have to edit:

    with your COM settings:

    or with device:
    #Determine this value from the pciconf -l

    thanks to Derelict you can have a look here:

    and here for AMT related:

    and freebsd doc:

  • Rebel Alliance Developer Netgate

    You can't add a USB serial adapter as a console, at least not that I've ever seen work. The USB device is not present early enough for it to be viable as a console for debugging purposes. It's a path that only leads to anger, heartache, and disappointment.

    You can turn a cheap rpi or similar into a network/OOB USB serial console mux/server that connects to loads of other USB serial consoles quickly and easily with off the shelf hardware and without modding anything. Just USB hub(s) and such.

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