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Twitter- Server operating system version
- Ubuntu 20.04
- Plesk version and microupdate number
- 18.0.61 #1
TL;DR: not a question, just a summary of how I approached and fixed the issue on one of my systems.
For the longest time Plesk updates have been showing the error “Warning: install PAM module not successed” on one of my Plesk installations. While this message is a bit scary to read, the installer always claimed that all changes had been executed successfully. And I never experienced any negative effects, indeed. So I got used to ignoring the error years ago.
Today I stepped over it once more and I finally took the time to investigate it further.
This is the message appearing in the installation log:
Google wasn’t very helpful as I found exactly one result complaining about the same error, but without any solution. The forum didn’t have anything good to tell either at this point.
Even though there is no clear indication which (.deb) package exactly is causing the issue, its pretty obvious that it must PAM related. libpam-plesk seems to be a good candidate. So I grabbed it form /var/cache/apt and to have a look at its content.
This got me a bunch of files and directories to look at.
Unfortunately the message “install PAM module” can’t be found inside any of them, but there is a “uninstall PAM module” message, so I considered myself being on the right track.
After some more digging I found that postinst calls /opt/psa/bootstrapper/components/libpam-plesk.sh which contains “install PAM module”. Yay!
This bootstrapper script finally calls the binary /opt/psa/pam_plesk_config/pam_plesk_install. Uuuh, a binary?
This time a search here on the forum gave me 2 hints: a) people have been calling pam_plesk_install multiple times without doing any futher harm and b) pam plesk_install supports -v for more verbosity.
Not too helpful, but there are references to .py files? Ok... so this “binary” might be just a collection of Python scripts. The first two bytes of the file header read PK... maybe its a simple ZIP file?
Indeed! Now we’re talking...
Crawling the source code was challenging and I will not claim to understand everything or even try to document the steps, but my summary is: `pam_plesk_install` verifies/analyzes all files in `pam.d`, regardsless if it needs to touch them or not. So this might be something completely unrelated to plesk.
BTW: PAMConfig/analyzers.py
And heres the root cause: a completely different service (Acronis Backup Manager) referenced system-auth in one of its own pam.d files. Appearantly system-auth is not available in Ubuntu 20.04 (anymore?) and pam_plesk_install can’t get any details about it. That ultimately crashed the script!
acronisagent.system
Since I didn’t use Acronis for a long time, my fix was easy: just get rid of BackupManager. Or: So I thought... but thats another story which will be told another day (and probably elsewhere). Hint: Don’t trust Acronis’ uninstaller to not touch files in /usr/sbin it doesn’t own!
Anyways, the takeaway is: The error described here is gone for good after removing any invalid/outdated entries from pam.d files.
Did anyone else run over this before?
For the longest time Plesk updates have been showing the error “Warning: install PAM module not successed” on one of my Plesk installations. While this message is a bit scary to read, the installer always claimed that all changes had been executed successfully. And I never experienced any negative effects, indeed. So I got used to ignoring the error years ago.
Today I stepped over it once more and I finally took the time to investigate it further.
This is the message appearing in the installation log:
Google wasn’t very helpful as I found exactly one result complaining about the same error, but without any solution. The forum didn’t have anything good to tell either at this point.
Even though there is no clear indication which (.deb) package exactly is causing the issue, its pretty obvious that it must PAM related. libpam-plesk seems to be a good candidate. So I grabbed it form /var/cache/apt and to have a look at its content.
Code:
# ar -x ../libpam-plesk_18.0-v.ubuntu.20.04+p18.0.61.0+t240426.1307_amd64.deb
# tar xJf control.tar.xz
# tar xJf data.tar.xzUnfortunately the message “install PAM module” can’t be found inside any of them, but there is a “uninstall PAM module” message, so I considered myself being on the right track.
After some more digging I found that postinst calls /opt/psa/bootstrapper/components/libpam-plesk.sh which contains “install PAM module”. Yay!
This bootstrapper script finally calls the binary /opt/psa/pam_plesk_config/pam_plesk_install. Uuuh, a binary?
This time a search here on the forum gave me 2 hints: a) people have been calling pam_plesk_install multiple times without doing any futher harm and b) pam plesk_install supports -v for more verbosity.
Code:
# /usr/local/psa/pam_plesk_config/pam_plesk_install -v
DEBUG:Loading PAM configuration from (directory="/etc/pam.d", file="/etc/pam.conf")
INFO:PAM configuration loaded from (directory="/etc/pam.d", file="/etc/pam.conf"). Configuration contains 29 file(s)
DEBUG:calculating changes for 'auth' stacks
DEBUG:S3:Traceback (most recent call last):
File "pam_plesk_install.py", line 351, in main
File "pam_plesk_install.py", line 35, in getAuthChanges
File "PAMConfig/analyzers.py", line 130, in selectServices
shared = confSet.getCommonServiceNames(self.facility)
File "PAMConfig/confset.py", line 958, in getCommonServiceNames
if self.getConf(c, facility):
File "PAMConfig/confset.py", line 980, in getConf
raise PAMServiceError(service)
PAMConfig.confset.PAMServiceError: system-auth
CRITICAL:3:a programming/runtime error (PAMConfig.confset.PAMServiceError: system-auth)Not too helpful, but there are references to .py files? Ok... so this “binary” might be just a collection of Python scripts. The first two bytes of the file header read PK... maybe its a simple ZIP file?
Code:
# unzip pam_plesk_install
Archive: pam_plesk_install
inflating: .bootstrap/__init__.py
[...}Indeed! Now we’re talking...
Crawling the source code was challenging and I will not claim to understand everything or even try to document the steps, but my summary is: `pam_plesk_install` verifies/analyzes all files in `pam.d`, regardsless if it needs to touch them or not. So this might be something completely unrelated to plesk.
BTW: PAMConfig/analyzers.py
Well... yeah, by now I think I know what you mean!
And heres the root cause: a completely different service (Acronis Backup Manager) referenced system-auth in one of its own pam.d files. Appearantly system-auth is not available in Ubuntu 20.04 (anymore?) and pam_plesk_install can’t get any details about it. That ultimately crashed the script!
acronisagent.system
Since I didn’t use Acronis for a long time, my fix was easy: just get rid of BackupManager. Or: So I thought... but thats another story which will be told another day (and probably elsewhere). Hint: Don’t trust Acronis’ uninstaller to not touch files in /usr/sbin it doesn’t own!
Anyways, the takeaway is: The error described here is gone for good after removing any invalid/outdated entries from pam.d files.
Did anyone else run over this before?
