James B. Byrne wrote:

I encountered a couple of strange events with respect to password authentication this morning. Two of our staff were unable to login onto several systems using their usual passwords. Both users had last logged in on these hosts using their accounts and passwords on Friday past.

<snip>

Resetting both the passwords to their current values using the passwd utility on each system corrected the problem insofar as the users were concerned. However, I am somewhat perplexed as to the reason for their passwords to stop working in the first place. Is anyone here aware of any reason why this might happen?

Is it possible that they'd logged into something else first, and had multiple credentials, and the systems were trying to get those first?

mark

The /etc/shadow file has fields that control account login properties. The following is out of the man file for /etc/shadow:

struct spwd { char *sp_namp; /* user login name */ char *sp_pwdp; /* encrypted password */ long sp_lstchg; /* last password change */ int sp_min; /* days until change allowed. */ int sp_max; /* days before change required */ int sp_warn; /* days warning for expiration */ int sp_inact; /* days before account inactive */ int sp_expire; /* date when account expires */ int sp_flag; /* reserved for future use */ }

Could it be that the expiration field was set such that the passwords expired?

-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of James B. Byrne Sent: 03 January 2012 17:31 To: centos@centos.org Subject: [CentOS] Passwords apparently stopped working.

I encountered a couple of strange events with respect to password authentication this morning. Two of our staff were unable to login onto several systems using their usual passwords. Both users had last logged in on these hosts using their accounts and passwords on Friday past.

The two accounts could not log on to any of the servers for which they had access and the message log on each showed that access was denied for a failed password. The systems involved were running either CentOS-4.9 or CentOS-5.7. So, the effect was uniform across multiple hardware and software platforms. I also checked these accounts against our warm backup machine and encountered the same problems for both.

I verified that the passwords being used were correct for the accounts. I also verified that neither of passwords had been reset in some months and there were no expiry dates set for the accounts.

I would accept the coincidence of both forgetting their passwords except for the fact that each had kept a record of their password in their wallets and I was able to confirm those values against our records as well.

Resetting both the passwords to their current values using the passwd utility on each system corrected the problem insofar as the users were concerned. However, I am somewhat perplexed as to the reason for their passwords to stop working in the first place. Is anyone here aware of any reason why this might happen?