Serial console

Some servers do not have a KVM/IP but allow the visualization of a video output on a serial console.

Its functions are more basic.

1. Go to the servers status page in your account
2. Click on KVM/IP:

3. Create a session to get the credentials:

Now you can access the serial console of your server:

You can now interact with the server, even if you have locked out yourself by a malicious network configuration, for example.

Configuration

It is possible, that the serial console is not activated by default on certain installations.

Here is how to activate it:

On SystemD based operating systems

  • CentOS 7
  • Fedora
  • ArchLinux
  • CoreOS

To activate it on each reboot:

# systemctl enable getty@ttyS1.service

To activate it on an already booted server:

# systemctl start getty@ttyS1.service

On Ubuntu 14.04

Create the folder /etc/init/ttyS1.conf

# ttyS1 - getty
#
# This service maintains a getty on ttyS1 from the point the system is
# started until it is shut down again.

start on stopped rc RUNLEVEL=[12345]
stop on runlevel [!12345]

respawn
exec /sbin/getty -L 9600 ttyS1 vt102

After a reboot of the server, the serial console will be activated.

On Debian 7 (Wheezy)

1. Edit the file /etc/inittab.

2. Uncomment the following line

T1:23:respawn:/sbin/getty -L ttyS1 9600 vt100

To take the changes into effect type:

init q

GRUB

In certain cases, GRUB may not be configured to show the serial console.

1. Edit /etc/default/grub, then add/change the following lines:

GRUB_TERMINAL=serial
GRUB_SERIAL_COMMAND="serial --unit=1 --speed=9600 --word=8 --parity=no --stop=1"

2. Save the changes
3. Update your GRUB

update-grub or update-grub2.

On ESXi

Directly from the vSphere client:

1. Enter the Configuration tab (1). In the Software section click on Advanced Settings (2)

A new window will open. Go to VMKernel and open it by clicking on the small + icon on the left.

2. Click on Boot (1).

3. On the right side of the window, look for the VMKernel.Boot.com2_baud option
4. Enter 9600 (2) as value

5. Look for the VMKernel.Boot.tty2Port value
6. Enter com2 as value

7. Reboot the ESXi host. You can now use the serial console of your server.

On FreeBSD

1. Edit the /boot/loader.conf file

boot_multicons="YES"
boot_serial="YES"
comconsole_speed="9600"
console="comconsole"
comconsole_port="0x2F8"

This will activate the console during the boot process of your server.

2. Edit the /etc/ttys file to add the following information at the ttyu1 line

ttyu1   "/usr/libexec/getty std.9600"   vt100   on  secure

3. Reboot your server to access the serial console.