Upgrading to Debian 13 - Trixie
Intro
Important stuff first, Trixie is a toy Triceratops, from Toy Story movies, probably from the same set as Rex, owned by Bonnie Anderson.
Howto
Read the release notes, yeah long peice of text, but well worth it to avoid problems with transforming your worm to a triceratops dinosaur.
Improvements
SSHD
Edit the /etc/ssh/sshd_config to include latest algorithms:
KexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512,curve25519-sha256,curve25519-sha256@libssh.org
Problems on the way
Dovecot 2.4
Why this is not 3.0 is beyond me. Massive changes, consult the official documentation and test extensively. Manual action required.
A few years ago I have used tutorial by Thomas Leister and here is the update for Dovecot 2.4 that really helps.