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Christian
Asked: 2018-08-18 03:54:09 +0800 CST

Ubuntu-18.04 and libpam-google-authenticator not prompting for keyboard-interactive

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On a new Ubuntu 18.04.1 LTS (GNU/Linux 4.15.0-1017-aws x86_64), I have installed Google Authenticator [1] and configured it in the following way

/etc/pam.d/sshd
#@include common-auth
...
auth required pam_google_authenticator.so nullok


/etc/ssh/sshd_config
...
ChallengeResponseAuthentication yes
...
AuthenticationMethods publickey,keyboard-interactive

Which works on Ubuntu 16, but not Ubuntu 18 with the following error when trying to log in:

$ ssh ubuntu@server
ubuntu@server: Permission denied (keyboard-interactive).

It seems something has changed with the new version of Ubuntu.

When i enable debug, there is no further information

Aug 17 11:40:31 ip-10-0-0-182 sshd(pam_google_authenticator)[6834]: debug: start of google_authenticator for "ubuntu"
Aug 17 11:40:31 ip-10-0-0-182 sshd[6832]: error: PAM: Permission denied for ubuntu from X.X.X.X
Aug 17 11:40:32 ip-10-0-0-182 sshd[6832]: Connection closed by authenticating user ubuntu X.X.X.X port 61076 [preauth]

ps. The home directory is NOT encrypted

[1] apt-get install libpam-google-authenticator

ubuntu-18.04

1 Answers

  1. on 18.04, I tried removing the AuthenticationMethod line, and it worked for me

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