SSH server won't start, exit code 255

[Matt Wilson]

I keep trying to set up external SSH access using openssh server on my 18.04 system and it throws back this error

sudo service ssh status
● ssh.service - OpenBSD Secure Shell server
   Loaded: loaded (/lib/systemd/system/ssh.service; enabled; vendor preset: enabled)
   Active: failed (Result: exit-code) since Sat 2018-07-07 09:33:19 CDT; 12min ago
  Process: 3243 ExecStartPre=/usr/sbin/sshd -t (code=exited, status=255)

Jul 07 09:33:19 warehouse systemd[1]: ssh.service: Service hold-off time over, scheduling restart.
Jul 07 09:33:19 warehouse systemd[1]: ssh.service: Scheduled restart job, restart counter is at 5.
Jul 07 09:33:19 warehouse systemd[1]: Stopped OpenBSD Secure Shell server.
Jul 07 09:33:19 warehouse systemd[1]: ssh.service: Start request repeated too quickly.
Jul 07 09:33:19 warehouse systemd[1]: ssh.service: Failed with result 'exit-code'.
Jul 07 09:33:19 warehouse systemd[1]: Failed to start OpenBSD Secure Shell server.

I was in the process of uninstalling the openssh-server and ssh packages and was prompted to start a bug report. If it's in error, just let me know. My ssh config file is all default except for passwordauthentication = yes. I've toggled that to default as well, and still get the same error.

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: openssh-server 1:7.6p1-4
ProcVersionSignature: Ubuntu 4.15.0-23.25-generic 4.15.18
Uname: Linux 4.15.0-23-generic x86_64
NonfreeKernelModules: kpatch_livepatch_Ubuntu_4_15_0_23_25_generic_40
ApportVersion: 2.20.9-0ubuntu7.2
AptOrdering:
 openssh-server:amd64: Install
 ssh:amd64: Install
 NULL: ConfigurePending
Architecture: amd64
Date: Sat Jul 7 09:48:11 2018
ErrorMessage: installed openssh-server package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2018-07-07 (0 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.2
SSHDConfig:
 Error: command ['/usr/sbin/sshd', '-T'] failed with exit code 255: /etc/ssh/sshd_config: line 1: Bad configuration option: \342\200\213\342\200\213
 /etc/ssh/sshd_config: terminating, 1 bad configuration options
SourcePackage: openssh
Title: package openssh-server 1:7.6p1-4 failed to install/upgrade: installed openssh-server package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Alex Murray (alexmurray)]

It looks like the ssh server configuration file has become corrupted - notice the error message:

Error: command ['/usr/sbin/sshd', '-T'] failed with exit code 255: /etc/ssh/sshd_config: line 1: Bad configuration option: \342\200\213\342\200\213
 /etc/ssh/sshd_config: terminating, 1 bad configuration options

Have you edit this file? Can you please make sure it is valid.

[Joshua Powers (powersj)]

Per the comment above, please take a look at your sshd_cofig file and verify it is valid. I am marking this incomplete until then.

[Launchpad Janitor (janitor)]

[Expired for openssh (Ubuntu) because there has been no activity for 60 days.]