Running a serial login terminal under systemd

TL;DR:

$ sudo systemctl edit serial-getty@ttyUSB0
[Service]
ExecStart=
ExecStart=-/sbin/agetty -o '-p -- \\u' 115200 %I $TERM
StandardInput=null
StandardOutput=journal
TTYPath=
TTYReset=no
TTYVHangup=no

From the other node:

$ tio /dev/ttyUSB0

I have a MINI PC in the comm area which hosts a few useful services at home. I got tired of how unstable the Raspberry Pi is, so replaced it with something that is almost as power efficient, but runs orders of magnitude faster. With support for both an SSD and an NVMe I can have software RAID for extra reliability.

The problem is that the onboard network (something based on RTL8111) insists on running at 100M and keeps flapping up and down. Got tired of troubleshooting it so got a USB network adapter which runs at 1G and is much more stable. Recently I noticed that the link would die, and as I have no way of getting into the machine easily to troubleshoot, I decided to give it a serial console.

Got a male USB to serial converter, and another female USB to serial converter for the other node. What I thought should be a matter of `sudo systemctl enable --now serial-getty@ttyUSB0` did not work. Following most online advice to change the `ExecStart` also did not work. It seems that a recent change to systemd to manage the serial port and connect the agetty process to it is not working as expected, so my fix is to revert it to the previous behavior. Just put the `TTY` related settings back to their defaults in the override drop-in and that's it.

Comments

Post a Comment

Popular posts from this blog

FreeIPA cluster with containers

Notes on how to install a FreeIPA cluster on Ubuntu. Mostly following the instructions on https://github.com/freeipa/freeipa-container Start with what would be the primary host. If you install a third replica you would want to review the replica agreements to ensure you have a two-way replication between all pairs of nodes.
Read more

ADSL Router Model CT-5367 user and pass (VIVACOM)

Writing down the username and password for the vivacom ADSL router, in case I need it again. user: root pass: warmWLspot Useful to telnet 192.168.1.1 and then reboot . Originally found at Neo2SHYAlien blog . And here I found passwords for other models, just in case. ZTE ZXDSL 832 username: root password: GSrootaccess ZTE ZXDSL 831 username: root password: GSrootaccess ZTE username: root password: 831access Huawei SmartAX MT882 username: root password: MT882rootaccess ZTE ZXDSL-531b username: root password: rootWLaccess Pirelli – DRG – A124G username: root password: warmWLspot Comtrend CT-5367 username: root password: warmWLspot HG530 Home Gateway username: root password: warmWLspot
Read more

Installing Gentoo with full disk encryption

The purpose of this exercise - install Gentoo where all disk partitions are encrypted. Boot from a system rescue disk and partition the disk - use GPT partition table where the first partition is reserved, second is the boot, and the third one is for the rest of the data. Device Start End Sectors Size Type /dev/sda1 2048 32767 30720 15M BIOS boot /dev/sda2 32768 442367 409600 200M Linux filesystem /dev/sda3 442368 375093902 374651535 178.7G Linux filesystem Encrypt partitions number 2 and 3, and open them cryptsetup luksFormat /dev/sda2 cryptsetup luksFormat /dev/sda3 cryptsetup luksOpen /dev/sda2 crypt_boot cryptsetup luksOpen /dev/sda3 crypt_data Format the boot partition mkfs.btrfs /dev/mapper/crypt_boot Prepare LVM for the rest, and format the top level vgcreate vg0 /dev/mapper/crypt_data lvcreate -l 100%FREE -n data vg0 mkfs.btrfs /dev/vg0/data Mount and set up any subvolumes mount /dev/vg0/data /mnt/gentoo btrfs subvol create /mnt/gentoo/@ /mnt/gentoo/@home umount /mnt/gentoo Now...
Read more