| Where user identity is stored? | /etc/passwd -user account info
/etc/shadow -encrypted passwords
/etc/group -system groups
these are ASCII files |
| Difference between user name and user id | UID is used for most purposes, each is assigned with a name |
| What kinds of accounts can be distinguished? | root
regular users
system accounts |
| Where valid login shelss are stored? | /etc/shells |
| What root user can do with passwords? | It doesn't know them but it can change them |
| command used for password change | passwd user_name |
| command that generates random secure passwords | pwgen |
| Is each user assigned to a primary group? | Yes it is
It can also be assigned to secondary groups |
| What is Pluggable Authentication (PAM) | It is an authentication mechanism performed by invoking a sequence of procedures |
| Where PAM configuration is stored? | in /etc/pam.conf file
and in /etc/pam.d directory |
| What is NSS Name Service Switch? | It allows for queying additional sources defined in /etc/nsswitch.conf
for users and groups |
| command that allows for searching through databases such as passwd or group
it is a line interface for NSS | getent passwd
getent group |
| What is the difference between PAM and NSS | PAM modules are used for authentication tasks
NSS is used for obtaining UID GID and additional info about user |
| command that allows to run command as other user | su - username
- denotes home directory
if no user is specified the default is root
regular users are prompted for passwords |
| command to add users | useradd
new accounts have invalid passwords by default |
| Where is each file or directory assigned ? | to a pair
owner
group |
| What can file owner do? | manage file permissions
manage file group
deinfe limits |
| Who can change file ownership? | root |
