CentOS Authentication Token Issues

Authentication tokens in CentOS (and other Linux systems) are part of the PAM (Pluggable Authentication Modules) system and are used to maintain user sessions. Here's what you need to know about authentication tokens in CentOS:

Common Authentication Token Issues

1. "Authentication token manipulation error"

   • Typically occurs when changing passwords
   • Common causes:
     • Full /etc or / partition
     • Corrupted PAM configuration
     • Filesystem permissions issues
     • SELinux context problems

2. "Authentication token is no longer valid"

   • Usually means the user's session has expired or credentials changed

Troubleshooting Steps

For "Authentication token manipulation error":

1. Check disk space:

   df -h
   

   • Clear space if partitions are full

2. Verify PAM configuration:

   authconfig --test
   

3. Check file permissions:

   ls -la /etc/pam.d/
   ls -la /etc/shadow
   

4. Check SELinux context:

   ls -Z /etc/shadow
   restorecon -v /etc/shadow
   

5. Force password change:

   passwd -d username
   passwd username
   

For expired/invalid tokens:

1. Check account status:

   chage -l username
   

2. Reset authentication tokens:

   pam_tally2 --user=username --reset
   

3. Clear cached credentials:

   kdestroy
   

Prevention

1. Regularly monitor disk usage
2. Maintain proper file permissions (shadow should be 000)
3. Keep PAM configurations clean
4. Consider using faillock for better authentication tracking

Would you like me to elaborate on any specific aspect of CentOS authentication tokens?