COMP1298-01 Networks and Applications 10

In order to send a print job to a printer using CUPS, what command must be used?

lp

On Linux, the root user always has a UID of what number?​

0

What priority used by the System Log Daemon indicates a very serious system condition that would normally be broadcast to all users?​

panic

What option can be added to the userdel command to remove the home directory of the target user?

-r dash lowercase r

What option can be used in the journald configuration file to specify a file size limit to the event log?​

SystemMaxUse

Adding the -t option to what command below will provide a list of all printers on the system and their status?

lpstat

What is the default print job priority for all print jobs created by the lp command?

50

he System Log Daemon uses what TCP and UDP port to accept incoming requests from another System Log Daemon on a remote system?

514

What System Log Daemon priority indicates an error that should be rectified immediately, such as a corrupt system database?

alert

​The CUPS Web administration tool can be accessed via web browser by accessing what TCP port below?

631

What log file contains information and error messages regarding network access generated by daemons such as ssd and xinetd?

secure

Where is the skeleton directory located on most Linux systems?

/etc/skel dash etc dash skel

Select the option that can be used with the lpstat command to display a list of printers that are enabled:

-p dash p

What option should be used in conjunction with the lp command in order to specify the destination printer name?

-d dash d

A user account can be locked with the usermod command using what option?

-L dash L

The System Log Daemon uses what TCP and UDP port to accept incoming requests from another System Log Daemon on a remote system?​

514

​What configuration file contains parameters that set the default location for e-mail, password expiration information, minimum password length, and the range of UIDs and GIDs available for use?

​login.defs

In order to create user accounts on a Linux system, what command should be utilized?

useradd

A system that uses an /etc/passwd file only can be converted to use /etc/shadow for security by using what command?

pwconv

Which command should be used to restrict access to printers?

lpadmin

To change the primary group temporarily to another group that is listed in the output of the groups and id commands, you can use which command below?

newgrp

Describe how the /etc/passwd and /etc/shadow files are used in the authentication process. Why are two files used instead of one? How can you convert a system to use the /etc/shadow file to store passwords?

The system database that contains user account information typically consists of two files: /etc/passwd and /etc/shadow. Every user typically has a line that describes the user account in /etc/passwd and a line that contains the encrypted password and expiration information in /etc/shadow. ​ Older Linux systems stored the encrypted password in the /etc/passwd file and did not use an /etc/shadow file at all. This is considered poor security today because processes often require access to the user information in /etc/passwd. Storing the encrypted password in a separate file that cannot be accessed by processes prevents a process from obtaining all user account information. By default, Fedora 13 configures passwords using an /etc/shadow file. However, you can use the pwunconv command to revert to using an /etc/passwd file only. Also, you can use the pwconv command to configure the system again using an /etc/shadow file for password storage.

How do you delete a user account? When you delete a user account, what gets deleted and what does not? What happens to the user’s files?

To delete a user account, you can use the userdel command and specify the user name as an argument. This removes entries from the /etc/passwd and /etc/shadow files corresponding to the user account. Furthermore, you can specify the -r option to the userdel command to remove the home directory for the user and all of its contents. When a user account is deleted, any files that were previously owned by the user become owned by a number that represents the UID of the deleted user. Any future user account that is given the same UID then becomes the owner of those files.

In order to prevent unauthorized access, how can the shadow file be configured to enforce a password policy?​ What happens to accounts with expired passwords?

To ensure that passwords are changed, you can can set them to expire at certain intervals. Three fields of the /etc/shadow file indicate information about password expiration: min represents the number of days a user must wait before he changes his password after receiving a new one, max represents the number of days a user can use the same password without changing it, and warn represents the number of days before a password would expire that a user is warned to change his password. ​ When a password has expired, the user is still allowed to log in to the system for a certain period of time, after which point the user is disabled from logging in. The number of days after a password expires that a user account is disabled is represented by the disable1 field in /etc/shadow. In addition, you can choose to disable a user from logging in at a certain date, such as the end of an employment contract. The disable2 field in /etc/shadow represents the number of days since January 1, 1970 that a user account will be disabled.