[CentOS] Passwords apparently stopped working.

Paul (GPR Support) paul at gpr.co.za
Wed Jan 4 06:15:04 UTC 2012

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

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf
Of James B. Byrne
Sent: 03 January 2012 17:31
To: centos at 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?

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James B. Byrne                mailto:ByrneJB at Harte-Lyne.ca
Harte & Lyne Limited          http://www.harte-lyne.ca
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Hamilton, Ontario             fax: +1 905 561 0757
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