Jaime Frutos Morales's blog


How to connect to Cisco devices via serial port using GNU/Linux

Filed under: Linux, SysAdmin — acidborg @ 10:17

Description: to connect your computer to a Cisco device via its console port, you usually need a RJ45 rolled cable. You can use a RJ-45 to DB-9 Female if your computer has a serial port.

RJ-45 to DB-9 Female

To communicate through the serial port with the Cisco device, you need Minicom, a terminal emulator software.


  • Debian/Ubuntu based distros: sudo apt-get install minicom
  • Red Hat/Fedora based distros: sudo yum install minicom


  1. Check whether your serial port is detected by the kernel: dmesg | grep ttyS

    [ 0.485378] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
    [ 0.485739] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
  2. Run Minicom: sudo minicom
  3. Press Ctrl+A Z to enter Minicom’s menu.
  4. Press O to enter configuration submenu.
  5. Enter the serial port setup.
  6. Set the serial device (/dev/ttyS0 in this example).
  7. Press E to set the “Bps/Par/Bits”.
  8. Press C (9600 bps) and Q (8-N-1).
  9. Set software flow control to NO.
  10. Save the configuration as “cisco” (for example)
  11. Press Q to quit Minicom
  12. Run Minicom with the new configuration: sudo minicom cisco

Tip: if you need to send a “Break” through Minicom (on a password recovery operation, for example), use Ctrl+A F .


How to force a file system check on the next reboot on GNU/Linux

Filed under: Linux, SysAdmin — acidborg @ 14:52

Description: sometimes you need to force a file system check after you reboot your computer. This can be done in two ways:

If you are going to reboot right now:

  • Execute this command (the -F argument forces a file system check): sudo shutdown -Fr now

If you aren’t going to reboot right now:

  • Execute this command: sudo touch /forcecheck
  • Next time you reboot or start your computer, a file system check will be performed.

Alternatively, if you want to avoid a file system check, use this command to reboot your machine: sudo shutdown -fr now


I passed my CCNA exam!

Filed under: Studies, SysAdmin — acidborg @ 18:19

Last Friday, I passed my CCNA exam.

CCNA certification

I would like to thank GNS3‘s developers and community for their great work.


The Humble Indie Bundle #2

Filed under: Linux — acidborg @ 00:37

The Humble Indie Bundle strikes back. As I did before, I’ve already contributed by purchasing my copies of their cross-platform games (GNU/Linux, Windows, Mac).

I totally recommend them.

Create a free website or blog at WordPress.com.