Trying to connect to a Cisco router, in purpose to learn Cisco skills that could help me finding a job. So, I plugged a cable in the rj45 Console (blue) port of a Cisco 888 router, and other end into serial port. On Debian 10, I installed minicom, then searched for serial tty:

sudo dmesg | grep tty
[    0.108074] console [tty0] enabled
[    4.648840] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[    4.669401] 00:03: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A

So I set up minicom to use /dev/ttyS0 , with 9600 bauds/8N1, and saved this configuation as cisco. However, when launching sudo minicom cisco, nothing particular happens:

Welcome to minicom 2.7.1

Compiled on May  6 2018, 08:43:56.
Port /dev/ttyS0, 09:17:07

Press CTRL-A Z for help on special keys

CTRL-A Z for help | 9600 8N1 | NOR | Minicom 2.7.1 | VT102 | Offline | ttyS0

Tried to reset the router (with the physical button), restarting it, unplug and replug the serial cable... but nothing happened.

==> How to initiate communication with the router ? Isn't it automatically launching a terminal when connecting to it over serial console cable ?

  • 1
    Unfortunately, this is something that gets asked here often, but there really is not much we can do to help, other than tell you that you need to try different combinations of parameters, such as the speed. The router could be set to to a different speed and/or other parameter, or you may have a cabling problem (DTE-DTE).
    – Ron Maupin
    Jul 6, 2020 at 15:28
  • @RonMaupin ((1)) Thank you, your comment is helpful because at least I know that I am in the right direction: with some good combination, the above command should directly give a prompt. ((2)) Have you some links to these related questions ? Before asking I searched but found nothing.
    – ymudyruc
    Jul 6, 2020 at 16:33
  • Search here for cisco console. I just did and found some with the same or related problems. Also, many of them may have been deleted by the OP or by the community for lack of activity because it is a difficult problem.
    – Ron Maupin
    Jul 6, 2020 at 16:38
  • Be sure to try all of your physical serial ports in case they're out-of-order. If the ports are internally connected to your PC's motherboard via ribbon cables, make sure they are really hooked up. Trying a USB-to-Serial cable isn't a bad idea, either. Jul 6, 2020 at 16:47
  • @JeffWheeler Is the gived dmesg output sufficient to ensure the port is alive ?
    – ymudyruc
    Jul 6, 2020 at 16:51

1 Answer 1


Isn't it automatically launching a terminal when connecting to it over serial console cable ?

Answer : no.

Simply need to reboot the router (eg power off and on), so it begins sending serial stuff to console port.

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