It is taking several attempts for users to SSH to several 64-bit Ubuntu machines which are using sssd to authenticate.
The following will happen from 0-6 times in a row before the user is allowed to log in:
ssh [email protected]
[email protected]'s password:
Connection closed by 10.13.63.101
It takes several seconds for the Connection closed by 10.13.63.101 error to occur.
Here is a sample from /var/log/auth.log which shows a failure followed by a success:
sshd[7098]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=x.x.x.x user=User
sshd[7098]: pam_sss(sshd:auth): authentication success; logname= uid=0 euid=0 tty=ssh ruser= rhost=x.x.x.x user=User
sshd[7098]: pam_sss(sshd:account): Access denied for user User: 4 (System error)
sshd[7098]: Failed password for bob from x.x.x.x port 54817 ssh2
sshd[7098]: fatal: Access denied for user bob by PAM account configuration [preauth]
sshd[7106]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=x.x.x.x user=bob
sshd[7106]: pam_sss(sshd:auth): authentication success; logname= uid=0 euid=0 tty=ssh ruser= rhost=x.x.x.x user=bob
sshd[7106]: Accepted password for bob from x.x.x.x port 54826 ssh2
sshd[7106]: pam_unix(sshd:session): session opened for user User by (uid=0)
systemd-logind[529]: Removed session 69.
systemd-logind[529]: New session 70 of user bob.
It seems the important line is the third one from the above output:
sshd[7098]: pam_sss(sshd:account): Access denied for user User: 4 (System error)
According to sssd's official wiki (https://fedorahosted.org/sssd/wiki/Troubleshooting):
System Error is an "Unhandled Exception" during authentication. It can either be an SSSD bug or a fatal error during authentication.
The sssd package is up to date:
$ sudo apt-get install sssd
sssd is already the newest version.
So far this is only affecting a very small sample of our systems (~4 of dozens).
Update:
It appears the sssd logs are either empty or months old.
bob@system:/var/log/sssd$ ls -l
total 16
-rw------- 1 root root 0 Jan 26 2015 ldap_child.log
-rw------- 1 root root 0 Jan 26 2015 sssd_LDAP.log
-rw------- 1 root root 0 Aug 5 06:49 sssd.log
-rw------- 1 root root 268 Aug 4 16:24 sssd.log.1
-rw------- 1 root root 158 Jun 15 11:47 sssd.log.2.gz
-rw------- 1 root root 139 May 25 13:17 sssd.log.3.gz
-rw------- 1 root root 139 May 11 11:08 sssd.log.4.gz
-rw------- 1 root root 0 Jan 26 2015 sssd_nss.log
-rw------- 1 root root 0 Jan 26 2015 sssd_pam.log
