Lost ssh access after running update using pacman [resolved]

audiomuze · 2017-03-22 03:29:07

My headless server has been running Arch for over a year without any issues and ssh has also worked without issue during this time. Yesterday I ran an arch update which ran successfully, however, after rebooting to take account of kernel updates I could no longer access the server via ssh - not as a regular user nor as root (which is previously explicitly re-enabled quite some time back). I know it's rebooted successfully as the server application it runs is accessible by its clients on the network and I can NFS mount the server drives.

Before I dig out a monitor and keyboard, have there been any recent changes to Arch that would trigger this?

Last edited by audiomuze (2017-03-22 08:20:16)

jasonwryan · 2017-03-22 03:49:52

Read the pacman log and the journal entries for the ssh service.

audiomuze · 2017-03-22 04:03:55

How? I don't have access to the server OS. I guess I could pull the flash drive it boots from and pop it in my Arch desktop machine.

Last edited by audiomuze (2017-03-22 04:08:09)

jasonwryan · 2017-03-22 04:22:30

You said in your first post you could pull out a monitor and keyboard...

audiomuze · 2017-03-22 07:58:24

Unfortunately my logs on that box aren't persistent as they're written to tmpfs. Anyhow, the problem seems to me to be upstream with sshd.service or a change to /etc/ssh/sshd_config. systemctl status sshd.service returns:

sshd.service - OpenSSH Daemon
Loaded: loaded (/usr/lib/systemd/sshd.service; enabled; vendor preset: disabled)
Active: failed (Result: exit-code) since Wed 2017-03-22 08:44:57 SAST; 20min ago
Process: 681 ExecStart=/usr/bin/sshd- D (code=exited, status=255)
Main PID: 681 (code=exited, status=255)

Tried reinstalling it and got same outcome.

Looked at timestamp of /etc/ssh/sshd_config and I see it was changed last night ... so I'm guessing some config was modified by the update and went awry.

Damnit, chasing the rabbithole.

Last edited by audiomuze (2017-03-22 08:04:09)

audiomuze · 2017-03-22 08:03:46

Yip, reverted to an earlier sshd_config and all's good again. Should I be reporting a bug ?

jasonwryan · 2017-03-22 08:17:19

No. The update shouldn't have touched your config, it should have created a .pacnew that you can compare with your current config.

What is the diff between the two configs?

audiomuze · 2017-03-22 08:19:22

These are the changes made by the update:
--- sshd_config.bk
+++ sshd_config
@@ -97,12 +97,11 @@
UsePAM yes

#AllowAgentForwarding yes
-AllowTcpForwarding yes
+#AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
-X11DisplayOffset 10
-X11UseLocalhost yes
-ForwardX11Trusted yes
+#X11DisplayOffset 10
+#X11UseLocalhost yes
#PermitTTY yes
PrintMotd no # pam does that
#PrintLastLog yes

Last edited by audiomuze (2017-03-22 08:20:39)

jasonwryan · 2017-03-22 08:29:47

You should work out why your config was overwritten, rather than pacnew'ed. I also don't see any change that would lock you out...

audiomuze · 2017-03-22 10:17:23

I learned something today. I see there is a pacnew. It might've been me that made the x11 related changes as I've been using x-forwarding of late. Still, nor sure why the server speed working with those changes... Guess I need to go read some.

Arch Linux

#1 2017-03-22 03:29:07

Lost ssh access after running update using pacman [resolved]

#2 2017-03-22 03:49:52

Re: Lost ssh access after running update using pacman [resolved]

#3 2017-03-22 04:03:55

Re: Lost ssh access after running update using pacman [resolved]

#4 2017-03-22 04:22:30

Re: Lost ssh access after running update using pacman [resolved]

#5 2017-03-22 07:58:24

Re: Lost ssh access after running update using pacman [resolved]

#6 2017-03-22 08:03:46

Re: Lost ssh access after running update using pacman [resolved]

#7 2017-03-22 08:17:19

Re: Lost ssh access after running update using pacman [resolved]

#8 2017-03-22 08:19:22

Re: Lost ssh access after running update using pacman [resolved]

#9 2017-03-22 08:29:47

Re: Lost ssh access after running update using pacman [resolved]

#10 2017-03-22 10:17:23

Re: Lost ssh access after running update using pacman [resolved]

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