I am trying to configure a Cisco (small business 300) via serial port. I read here: http://www.commandlinefu.com/commands/view/6130/use-screen-as-a-terminal-emulator-to-connect-to-serial-consoles

That I can use screen to connect to the switch, but when I try the command

screen /dev/ttyUSB0 9600

All I get is a bunch of weird characters.

The gear is connected via a Logilink serial-usb adapter. I had found the name of the chip in that, but now I can't seem to find it again.

This is on Debian 7.0, but I have tried it on a Linux Mint as well. Didn't work either.

Tried minicom first, didn't work. Which was why I turned to Google and found the above site. It seems to work well with screen though, meaning I have just tried it on a windows 7+putty with the newest drivers and it produces the exact same output as with screen. So I am starting to think the damn dongle might be broken.

  • Not an answer, but I personally use putty for this. Configuration is a bit easier.
    – jordanm
    Commented Mar 21, 2013 at 18:36
  • 2
    Putty is usually Windows-centric. I personally use minicom to connect to an ASA. Works just fine.
    – schaiba
    Commented Mar 21, 2013 at 19:01
  • added some clarification. Commented Mar 21, 2013 at 20:58
  • screen works fine for serial connections, but you have to supply it with the correct speed and negotiation options. Weird characters can occur when you have the wrong ones - or a bad cable. Commented Mar 23, 2013 at 14:47

1 Answer 1


As it turns out. The fault was neither the dongle, nor was it screen.

The Small Business 300 series uses 115200 baud unlike the rest of cisco's equipment that uses 9600 baud.

Using the command:

screen /dev/ttyUSB1 115200

Did the trick. Thanks for playing guys :)

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