Connecting to a cisco device using serial console cable from pfsense



  • hi
    I have installed pfsense on commoditiy grade pc for my home lab and it has a serial port. nowadays all new laptps and pads etc dont have this port.

    is there any possibility to establish a console connection with the switch if i connect the cable between the switch and the pfsesense serial port ?

    i couldnt find an obvious package to achieve above.

    dmesg | grep "uart"
    uart0: <16550 or compatible> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
    uart0: console (115200,n,8,1)



  • You'd need to install some terminal app on pfSense.  I use Minicom on Linux.  However, an alternative may be to buy a USB serial port adapter.  I bought one years ago and it works fine with Linux & Windows.  Then again, you can also use ssh to access pfSense from another computer.  It does everything you can do with a serial port.


  • LAYER 8 Global Moderator

    I would think you should just be able to use the cu command, I just checked and pfsense has it available calling out the specific port and rate you want to use, etc.



  • @johnpoz:

    I would think you should just be able to use the cu command, I just checked and pfsense has it available calling out the specific port and rate you want to use, etc.

    Thanks for the super quick response.
    i red at this site
    https://superuser.com/questions/476580/how-to-connect-to-cisco-w3550-with-freebsd

    that command "cu -l /dev/cuau0 -s 9600" can be used to connect to cisco from freebsd . if i run it form my pfsense i get below error.
    cu -l /dev/cuau0 -s 9600
    /dev/cuau0: Device busy
    link down

    I am doing this conoluted thing as my switch blown and the only serial to usb converter at hand is not working and no pc with serial atm with me. i am locked out.  above if work is a good band aid.

    the speed is set correctly.


  • LAYER 8 Netgate

    The only Cisco device I have with USB console is a 2901 Router.

    It enumerates as /dev/cuaU0 and I can cu to that but it doesn't respond at -s 9600.

    I can cu to the same router just fine from a mac on /dev/cu.usbmodem141

    Not sure what's up with that.

    The same workflow works just fine from pfSense/FreeBSD to another ADI unit: cu -l /dev/cuaU0 -s 115200.



  • and the only serial to usb converter at hand is not working

    Some Cisco gear has a built in USB converter.  You connect to it with a mini USB cable.  I've never tried it, as I always had a USB serial port adapter.  If it has one, it should work like any other USB serial port.


  • Banned

    Did you turn on the serial console in pfSense? In that case the port is already in use.


  • LAYER 8 Netgate

    That is cuau0 not cuaU0 which is why he was seeing that on cuau0.

    ls -l /dev/cu*

    connect the USB console.

    ls -l /dev/cu*

    The connected console will be the new devices.


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