Defining SSH cipher `rijndael-cbc@lysator.liu.se` as
```
set service ssh ciphers rijndael-cbc@lysator.liu.se
```
will break the daemon
```
Dec 13 20:08:27 systemd[1]: Starting OpenBSD Secure Shell server...
Dec 13 20:08:27 ip[5411]: /run/sshd/sshd_config line 53: Bad SSH2 cipher spec 'rijndael-cbc@lysator.liu.se'.
Dec 13 20:08:27 systemd[1]: ssh@default.service: Main process exited, code=exited, status=255/EXCEPTION
Dec 13 20:08:27 systemd[1]: ssh@default.service: Failed with result 'exit-code'.
Dec 13 20:08:27 systemd[1]: Failed to start OpenBSD Secure Shell server.
Dec 13 20:08:38 systemd[1]: ssh@default.service: Scheduled restart job, restart counter is at 10.
Dec 13 20:08:38 systemd[1]: Stopped OpenBSD Secure Shell server.
```
According to https://bbs.archlinux.org/viewtopic.php?id=188613 `rijndael-cbc@lysator.liu.se` was removed in OpenSSH 6.7 https://www.openssh.org/txt/release-6.7
> sshd(8): The default set of ciphers and MACs has been altered to remove unsafe algorithms. In particular, CBC ciphers and arcfour* are disabled by default.
The currently supported cipher list in Debian Bookworm (VyOS 1.4 and VyOS 1.5) is:
```
cpo@LR1.wue3:~$ ssh -Q cipher
3des-cbc
aes128-cbc
aes192-cbc
aes256-cbc
aes128-ctr
aes192-ctr
aes256-ctr
aes128-gcm@openssh.com
aes256-gcm@openssh.com
chacha20-poly1305@openssh.com
```