Serial terminal

Configuration on the host

1. Add a virtual serial port to the VM

qm set  -serial0 socket

(or)

echo "serial0: socket" >> /etc/pve/qemu-server/.conf

Configuration on the guest

Configure the terminal

1. Enable a serial console

systemctl enable serial-getty@ttyS0.service
systemctl start serial-getty@ttyS0.service

2. Instruct grub2 to send the boot messages on the serial port by editing `/etc/default/grub` and adding:

GRUB_CMDLINE_LINUX="quiet console=tty0 console=ttyS0,115200"

3. run `update-grub` afterward.

Allow password-less root login on the serial console

_TIPS_

Add in .bashrc

export SYSTEMD_EDITOR=vim

1. Run `systemctl edit serial-getty@ttyS0.service`, and add the following:

[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -- \\u' --keep-baud 115200,38400,9600 --noclear --autologin root ttyS0 $TERM

This will cause `agetty` to auto-login the `root` user, but with only this change the system will still prompt you for the root password.

-o  --login-option
-p  --login-pause
\u  user
-J --noclear (Do not clear the screen before prompting the login name. By deafult the screen is cleared)

2. We can configure `/etc/pam.d/login` to authenticate `root` logins on the console without a password. Add the following to the top of `/etc/pam.d/login`:

```

auth sufficient pam_listfile.so item=tty sense=allow file=/etc/securetty onerr=fail apply=root

```

This will cause the PAM stack to check for the login tty in `/etc/securetty`, and to skip other authentication mechanisms if it finds it.

3. Add the serial port to `/etc/securetty`.

```

echo ttyS0 >> /etc/securetty

```

Connecting to the Serial Terminal

On the host, just enter

qm terminal

and enter **enter** a second time to get the prompt.

*NOTE**: if it seems this is not working, and if you have defined ttyS1, you can connect to it with the command:

qm terminal  -iface serial1

Remember the `qm terminal` uses Ctrl-O as shortcut, so saving a file from `nano` with Ctrl-O will log you out instead.