I verified the fix using openssh-server 1:9.0p1-1ubuntu8.1 from lunar-proposed: Test 1: root@lunar:~# apt-cache policy openssh-server openssh-server: Installed: 1:9.0p1-1ubuntu8.1 Candidate: 1:9.0p1-1ubuntu8.1 Version table: *** 1:9.0p1-1ubuntu8.1 100 100 http://archive.ubuntu.com/ubuntu lunar-proposed/main amd64 Packages 100 /var/lib/dpkg/status 1:9.0p1-1ubuntu8 500 500 http://archive.ubuntu.com/ubuntu lunar/main amd64 Packages root@lunar:~# ssh localhost The authenticity of host 'localhost (::1)' can't be established. ED25519 key fingerprint is SHA256:AbCnblNKQGNc02dY90hZSSobjAiPKfXOOs0YFUhVe9c. This key is not known by any other names Are you sure you want to continue connecting (yes/no/[fingerprint])? no Host key verification failed. root@lunar:~# systemctl status ssh.service ● ssh.service - OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; disabled; preset: enabled) Drop-In: /etc/systemd/system/ssh.service.d └─00-socket.conf /run/systemd/system/service.d └─zzz-lxc-service.conf Active: active (running) since Mon 2023-05-15 13:51:10 UTC; 16s ago TriggeredBy: ● ssh.socket Docs: man:sshd(8) man:sshd_config(5) Process: 148 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS) Main PID: 149 (sshd) Tasks: 1 (limit: 18854) Memory: 1.3M CPU: 71ms CGroup: /system.slice/ssh.service └─149 "sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups" May 15 13:51:10 lunar systemd[1]: Starting ssh.service - OpenBSD Secure Shell server... May 15 13:51:10 lunar sshd[149]: Server listening on :: port 22. May 15 13:51:10 lunar systemd[1]: Started ssh.service - OpenBSD Secure Shell server. May 15 13:51:12 lunar sshd[150]: Connection closed by ::1 port 37598 [preauth] root@lunar:~# systemctl reload ssh root@lunar:~# systemctl status ssh.service ● ssh.service - OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; disabled; preset: enabled) Drop-In: /etc/systemd/system/ssh.service.d └─00-socket.conf /run/systemd/system/service.d └─zzz-lxc-service.conf Active: active (running) since Mon 2023-05-15 13:51:10 UTC; 23s ago TriggeredBy: ● ssh.socket Docs: man:sshd(8) man:sshd_config(5) Process: 148 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS) Process: 158 ExecReload=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS) Process: 159 ExecReload=/bin/kill -HUP $MAINPID (code=exited, status=0/SUCCESS) Main PID: 149 (sshd) Tasks: 1 (limit: 18854) Memory: 1.3M CPU: 127ms CGroup: /system.slice/ssh.service └─149 "sshd: /usr/sbin/sshd -D [listener] 0 of 10-100 startups" May 15 13:51:10 lunar systemd[1]: Starting ssh.service - OpenBSD Secure Shell server... May 15 13:51:10 lunar sshd[149]: Server listening on :: port 22. May 15 13:51:10 lunar systemd[1]: Started ssh.service - OpenBSD Secure Shell server. May 15 13:51:12 lunar sshd[150]: Connection closed by ::1 port 37598 [preauth] May 15 13:51:33 lunar systemd[1]: Reloading ssh.service - OpenBSD Secure Shell server... May 15 13:51:33 lunar sshd[149]: Received SIGHUP; restarting. May 15 13:51:33 lunar systemd[1]: Reloaded ssh.service - OpenBSD Secure Shell server. May 15 13:51:33 lunar sshd[149]: Server listening on :: port 22. Test 2: root@lunar:~# apt-cache policy openssh-server openssh-server: Installed: 1:9.0p1-1ubuntu8.1 Candidate: 1:9.0p1-1ubuntu8.1 Version table: *** 1:9.0p1-1ubuntu8.1 100 100 http://archive.ubuntu.com/ubuntu lunar-proposed/main amd64 Packages 100 /var/lib/dpkg/status 1:9.0p1-1ubuntu8 500 500 http://archive.ubuntu.com/ubuntu lunar/main amd64 Packages root@lunar:~# vi /etc/default/ssh root@lunar:~# cat /etc/default/ssh # Default settings for openssh-server. This file is sourced by /bin/sh from # /etc/init.d/ssh. # Options to pass to sshd SSHD_OPTS=-ddd root@lunar:~# ssh localhost The authenticity of host 'localhost (::1)' can't be established. ED25519 key fingerprint is SHA256:AbCnblNKQGNc02dY90hZSSobjAiPKfXOOs0YFUhVe9c. This key is not known by any other names Are you sure you want to continue connecting (yes/no/[fingerprint])? yes Warning: Permanently added 'localhost' (ED25519) to the list of known hosts. Welcome to Ubuntu 23.04 (GNU/Linux 6.2.0-20-generic x86_64) * Documentation: https://help.ubuntu.com * Management: https://landscape.canonical.com * Support: https://ubuntu.com/advantage The programs included with the Ubuntu system are free software; the exact distribution terms for each program are described in the individual files in /usr/share/doc/*/copyright. Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law. debug1: PAM: reinitializing credentials debug1: permanently_set_uid: 0/0 debug3: Copy environment: XDG_SESSION_ID=17 debug3: Copy environment: XDG_RUNTIME_DIR=/run/user/0 debug3: Copy environment: DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus debug3: Copy environment: XDG_SESSION_TYPE=tty debug3: Copy environment: XDG_SESSION_CLASS=user debug3: Copy environment: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin debug3: Copy environment: LANG=en_US.UTF-8 Environment: LANG=en_US.UTF-8 USER=root LOGNAME=root HOME=/root PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin SHELL=/bin/bash TERM=xterm-256color XDG_SESSION_ID=17 XDG_RUNTIME_DIR=/run/user/0 DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus XDG_SESSION_TYPE=tty XDG_SESSION_CLASS=user SSH_CLIENT=::1 38966 22 SSH_CONNECTION=::1 38966 ::1 22 SSH_TTY=/dev/pts/2 root@lunar:~# systemctl status ssh.service ● ssh.service - OpenBSD Secure Shell server Loaded: loaded (/lib/systemd/system/ssh.service; disabled; preset: enabled) Drop-In: /etc/systemd/system/ssh.service.d └─00-socket.conf /run/systemd/system/service.d └─zzz-lxc-service.conf Active: active (running) since Mon 2023-05-15 14:22:15 UTC; 8s ago TriggeredBy: ● ssh.socket Docs: man:sshd(8) man:sshd_config(5) Process: 153 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=0/SUCCESS) Main PID: 154 (sshd) Tasks: 0 (limit: 18854) Memory: 1.9M CPU: 89ms CGroup: /system.slice/ssh.service ‣ 154 "sshd: root@pts/2" May 15 14:22:17 lunar sshd[154]: debug1: server_input_channel_req: channel 0 request shell reply 1 May 15 14:22:17 lunar sshd[154]: debug1: session_by_channel: session 0 channel 0 May 15 14:22:17 lunar sshd[154]: debug1: session_input_channel_req: session 0 req shell May 15 14:22:17 lunar sshd[154]: Starting session: shell on pts/2 for root from ::1 port 38966 id 0 May 15 14:22:17 lunar sshd[154]: debug2: fd 5 setting TCP_NODELAY May 15 14:22:17 lunar sshd[154]: debug3: set_sock_tos: set socket 5 IPV6_TCLASS 0x10 May 15 14:22:17 lunar sshd[154]: debug2: channel 0: rfd 11 isatty May 15 14:22:17 lunar sshd[154]: debug2: fd 11 setting O_NONBLOCK May 15 14:22:17 lunar sshd[154]: debug3: fd 8 is O_NONBLOCK May 15 14:22:17 lunar sshd[154]: debug3: send packet: type 99