Every SSH connection exits with an abnormal code.

For example

ssh corti@myhost.example.com true

results in

Feb 11 10:16:47 mac-mini com.apple.xpc.launchd[1]: (com.openssh.sshd.163F2BE0-40C6-4B17-AB4E-5A0A07A524DE): Service instances do not support events yet.
Feb 11 10:16:48 mac-mini.home sshd[35674]: Accepted publickey for corti from ***.***.***.*** port 65030 ssh2
Feb 11 10:16:48 mac-mini.home sshd[35676]: Received disconnect from ***.***.***.***: 11: disconnected by user
Feb 11 10:16:48 mac-mini com.apple.xpc.launchd[1]: (com.openssh.sshd.163F2BE0-40C6-4B17-AB4E-5A0A07A524DE[35674]): Service exited with abnormal code: 255

Why is sshd exiting with a non zero return value (i.e., 225)?

  • 3
    I know this is old, but did you ever figure this out? I'm troubleshooting a nighttime problem with rsync and I've noticed that all of my launchd/sshd sessions on the server end with "abnormal code: 255". – tim.rohrer Aug 21 '16 at 17:20
  • I think I've found the solution. Checkout unix.stackexchange.com/questions/461851/… – pkgajulapalli Aug 13 '18 at 1:57

In recent macOS versions, the rotten fruit geniuses have restricted SSH access to admin users only. I was having this 'service exited with abnormal code' issue and I fixed it by Preferences -> Sharing -> Remote Login: On and 'Allow Access to': All Users (or the users/groups you want). You must be an admin to do that (you must be able to unlock the locker icon on the bottom left).

Two hours wasted, damn idiots...

  • 1
    That's not the problem I describe. The SSH login is working. It's result code of the ssh binary that always return 255. I have no problems with the connection – Matteo Jul 6 '18 at 15:52
  • 2
    But in my case the connection is successful: it’s only the code that is wrong. – Matteo Jul 6 '18 at 16:19
  • 1
    You mean you can login and start a sesion anyway? I couldn't. – zakmck Jul 6 '18 at 16:20
  • 2
    Yes exactly. It’s only the return code. – Matteo Jul 6 '18 at 16:42
  • 1
    I think its worth noting that this is probably the most common cause of this status code - the connection will open, and then close before the user is given a process. I think this change was wisely done by Apple, ebcause some apps/services install users, and a user who has enabled remote login then has open users with known default passwords on (who is unaware). I wouldn't recommend opening to 'all users', but I would recommend allowing specific users and maintaining control over who can and can't access your computer remotely. – Jmons Sep 19 at 10:14

I was running into this issue because of the default "Allow ssh access only to admin" setting, but wanted a command-line only solution.

I changed it by adding the user to the admin (and wheel for good measure) group:

sudo dscl localhost -append /Local/Default/Groups/admin GroupMembership $USER
sudo dscl localhost -append /Local/Default/Groups/wheel GroupMembership $USER

Make sure that your user corti has Remote Login feature enabled in Sharing Preferences.

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