Get USB serial port replicator working under Linux

Q I would love to junk Windows and run a pure Linux system. I have found equivalent software for everything I do and I know from the Live DVDs that my system will work. However I am studying for a Cisco CCNA qualification and use a serial port replicator connected to a USB port on my system. The serial end then connects to the console port on the Cisco Router via a serial-to-RJ11 crossover cable. Do you know how to get a USB serial port replicator working under Linux, and can you recommend a replacement for the Hyper Terminal and SolarWinds TFTP Server apps?

A By port replicator, I take it you mean a converter. A port replicator usually connects a port to an output of the same kind, as used on laptop docking stations. There are a variety of USB-to-serial converters out there, most of which are supported by Linux. I have two myself, both bought from eBay and using different chipsets and drivers, but both working perfectly under Linux. The kernel has a number of modules to drive these devices, which should be automatically loaded when you connect them. Run this command as root, or prefix it with sudo if running Ubuntu, before connecting the device

tail -f /var/log/messages

When you connect the device, you should see something like this:

usbcore: registered new interface driver usbserial
drivers/usb/serial/usb-serial.c: USB Serial Driver core
drivers/usb/serial/usb-serial.c: USB Serial support registered for ark3116
ark3116 5-2:1.0: ark3116 converter detected
usb 5-2: ark3116 converter now attached to ttyUSB0
usbcore: registered new interface driver ark3116

Here you can see that this device uses the ark3116 module and has created a serial device at /dev/ttyUSB0. You can see which USB serial drivers are available on your system with

ls -1 /lib/modules/$(uname -r)/kernel/drivers/usb/serial

If your device is not recognised, run the lsusb command to get its ID numbers and search for it at It may be that you have an unsupported device, (though that is unlikely), or that your kernel was not built with the appropriate modules, in which case you will have to recompile your kernel with the driver enabled. The standard serial terminal program for Linux is Minicom, which should be included with your distro. There are a number of TFTP servers available, including Atftp ( and NetKit TFTP ( although I prefer to use the TFTP server in dnsmasq (

Follow us on or Twitter

Username:   Password: