Console Redirection
To properly set up CentOS8 with COMe-bBD6 CPU, it could be necessary to use Console Redirection, as CPU do not provide graphic output. Console Redirection is a feature that transmits terminal interface through RS-232. It is possible then, to navigate within BIOS settings or have access to the operating system terminal straight on.
In order to do it, serial interfaces between host and target PCs needs to be connected by crossed cable and parameters of communication should be set up in the same manner.
BIOS:
Putty:
Additionally, the system is taking control of the serial interface after booting up. It is necessary to configure Console Redirection in the operating system as well, so one can have full control over the system with such a connection.
To do it in CentOS8, follow instructions below:
- Open grub within text editor: nano /etc/sysconfig/grub
- Find the line labeled GRUB_CMDLINE_LINUX and add console=ttyS0,115200 to the end (this assumes your serial port is ttyS0). It should look something like this: GRUB_CMDLINE_LINUX="rhgb quiet console=ttyS0,115200"
- Save the file and exit
- Run: stty -F /dev/ttyS0 speed 115200
- Then: grub2-mkconfig -o /boot/grub2/grub.cfg
- Finally: systemctl start getty@ttyS0
- And to automatically run service after startup: systemctl start getty@ttyS0
There was an issue with connecting to CentOS8 after OS installation with COMe-cKL6 CPU. It happened, that the network interface was disabled and Console Redirection was helpful to access the terminal and fix an issue. To enable it, one can use "sudo nmcli dev connect " Additionally, nmcli and nmtui commands could be useful for either debugging or configuring network interfaces.
Configuration of firewall for remote desktop within CERN network
In order to set up firewall in CERN network for xrdp connection, it is required to find internal IP address of the device, that connection would be initialized from. In my case, it was 137.138.76.235, so subnetwork including this address was added to firewall (--add-source=137.138.76.235/16) There is also an option to request for fixed IP address for the device at cern.ch/network, so the firewall can be set up accordingly.
sudo systemctl start xrdp
sudo firewall-cmd --new-zone=xrdp -–permanent
sudo firewall-cmd --zone=xrdp –-add-port=3389/tcp –-permanent
sudo firewall-cmd --zone=xrdp --add-source=137.138.76.235/16 --permanent
sudo firewall-cmd –-reload