Recently, the 11th point release of Debian 11 has been announced, and it will be the last one. For I am still maintaining one Debian 11 machine, I am starting to prepare its upgrade to Debian 12. Because it is a dual boot machine, I must not forget about the change of grub OS probing. Before I ugrade, I have to add GRUB_DISABLE_OS_PROBER=false to / etc/default/grub, or I lose grub menu for Windows OS. Another thing that impacts me is the change of gnome-text-editor. In Debian 11, gnome-text-editor is a kind of alias of gedit controlled under the Debian alternative system with update-alternatives command. On the other hand, a new package gnome-text-editor appears in Debian 12, and it is a different thing from gedit. For I am an uim user, I was confused when I tried to use launch a Japanese input method via uim on gnome-text-editor in Debian 12, for it wouldn't work as in Debian 11. Yes, these two things are important reminder to me.
I built and am running a mail server, using dovecot for IMAP4 server and Power DNS (pdns) for DNS authoritative server, and memcached for back-end service for some mail filter. I also use LXC for staging environment to test my mail server, but running those services is not straight forward. My understanding is that it is because some security features of systemd using Linux kernel namespace function conflict with the use of namespace in LXC container. So, if you want to run memcached, dovecot, and pdns via systemd within LXC container, you have to disable some security features of systemd by configuration. My additional configuration to systemd is as follows: root@myhost:/# cat /etc/systemd/system/memcached.service.d/99-ns.conf [Service] ProtectSystem = no ProtectHome = no PrivateDevices = no PrivateTmp = no cat /etc/systemd/system/dovecot.service.d/99-ns.conf [Service] ProtectSystem = no PrivateDevices = no PrivateTmp = no root@myhost:/# grep -v '#' /etc/systemd/system/pdns.s...