Hi Luke, thanks for reporting this issue. Unfortunately, I am not able to reproduce it.
Ubuntu 18.04.2 ships openssh-server 1:7.6p1-4ubuntu0.3, not 7.9. Is the version typo'd in the report or are you running a self-installed version of openssh perhaps? In any case, I attempted reproduction on both 18.04 (bionic) and 19.10 (eoan) in lxc, but was not able to reproduce a fault. If you could, please provide an exact set of commands to reproduce, and the error message you encountered. Please also verify you're running the stock distro version of openssh when doing - reproducing in a clean vanilla lxc instance or a fresh installation of ubuntu would be helpful. $ lxc launch ubuntu:18.04/amd64 lp1834129 $ lxc exec lp1834129 bash # apt-get update [...] # ps aux | grep sshd root 685 0.0 0.0 72296 5660 ? Ss 22:31 0:00 /usr/sbin/sshd -D root 687 0.0 0.0 14856 1008 ? S+ 22:31 0:00 grep --color=auto sshd # service sshd stop # ps aux | grep sshd root 718 0.0 0.0 14856 1116 ? S+ 22:31 0:00 grep --color=auto sshd # ls -l /run/ssh* ls: cannot access '/run/ssh*': No such file or directory # touch my_sshd_config # sshd -f ./my_sshd_config sshd re-exec requires execution with an absolute path # /usr/sbin/sshd -f ./my_sshd_config Missing privilege separation directory: /run/sshd # mkdir /run/sshd # /usr/sbin/sshd -f ./my_sshd_config # ps aux | grep sshd root 725 0.0 0.0 72296 3344 ? Ss 22:31 0:00 /usr/sbin/sshd -f ./my_sshd_config root 727 0.0 0.0 14856 1040 ? S+ 22:31 0:00 grep --color=auto sshd # kill 725 # !ps ps aux | grep sshd root 729 0.0 0.0 14856 1004 ? S+ 22:32 0:00 grep --color=auto sshd # mv /etc/ssh/sshd_config /tmp/ # /usr/sbin/sshd -f ./my_sshd_config # !ps ps aux | grep sshd root 732 0.0 0.0 72296 3200 ? Ss 22:32 0:00 /usr/sbin/sshd -f ./my_sshd_config root 734 0.0 0.0 14856 1156 ? S+ 22:32 0:00 grep --color=auto sshd # ls -l /etc/ssh/sshd_* ls: cannot access '/etc/ssh/sshd_*': No such file or directory # passwd ubuntu Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully # su ubuntu To run a command as administrator (user "root"), use "sudo <command>". See "man sudo_root" for details. $ ssh localhost ubuntu@localhost's password: To run a command as administrator (user "root"), use "sudo <command>". See "man sudo_root" for details. $ logout Connection to localhost closed. $ . /etc/lsb-release && echo ${DISTRIB_DESCRIPTION} Ubuntu 18.04.2 LTS $ ssh -V OpenSSH_7.6p1 Ubuntu-4ubuntu0.3, OpenSSL 1.0.2n 7 Dec 2017 $ apt-cache policy openssh-server | grep Installed Installed: 1:7.6p1-4ubuntu0.3 ** Changed in: openssh (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1834129 Title: Presence of sshd_config mandatory To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1834129/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs