Self Test

The following questions will help you measure your understanding of the material presented in this chapter. As no multiple choice questions appear on the Red Hat exams, no multiple choice questions appear in this book. These questions exclusively test your understanding of the chapter. It is okay if you have another way of performing a task. Getting results, not memorizing trivia, is what counts on the Red Hat exams. There may be more than one answer for many of these questions.

The Extended Internet Services Daemon (xinetd)

1.	You are using the xinetd program to start services. What command makes sure the Kerberos version of Telnet, as configured in /etc/xinetd.d/krb5-telnet, starts the next time you boot Linux? Assume the xinetd service is active. ________________________________________________________
2.	What command rereads any configuration changes you've made to a file in the /etc/xinetd.d directory? ________________________________________________________

Answers

1.	The command that makes sure that the Kerberos version of Telnet starts the next time you boot Linux is chkconfig krb5-telnet on. This assumes the xinetd service is active when you boot. Naturally, you can edit /etc/xinetd.d/krb5-telnet directly for the same result.
2.	The command that rereads any configuration changes you've made to a file in the /etc/xinetd.d directory is service xinetd reload.

The Secure Shell Package

3.	Once configured, what do you have to do to an existing firewall to allow Secure Shell (SSH) access? ________________________________________________________
4.	You've started the SSH service and have a local account under username troosevelt. The local computer name is conservation. How would you log into that account from a remote computer? ________________________________________________________
5.	Where are SSH keys stored for user michael? Assume a standard home directory. ________________________________________________________
6.	When configuring an SSH server, what directive prohibits SSH logins by the root user? ________________________________________________________
7.	When configuring an SSH server, what directive supports access to remote GUI applications? ________________________________________________________
8.	If you've configured access to remote GUI applications, how would you log into the account described in question 4? ________________________________________________________

Answers

3.	Once configured, you need to open TCP port 22 to allow Secure Shell (SSH) access. It's easy to do with the Red Hat Security Level configuration tool described in Chapter 15.
4.	To log into the troosevelt account from a remote computer, use the ssh troosevelt@conservation command.
5.	SSH keys for user michael are stored in the /home/michael/.ssh/directory.
6.	When configuring an SSH server, the directive that prohibits SSH logins by the root user is PermitRootLogin no.
7.	When configuring an SSH server, the directive that supports access to remote GUI applications is X11Forwarding yes.
8.	If you've configured access to remote GUI applications, you would use the ssh -X troosevelt@conservation command to log into the account described in question 5. You can then access GUI applications such as Firefox and OpenOffice.org writer through the SSH connection.

Dynamic Host Configuration Protocol (DHCP)

9.	What would you add to the /etc/dhcpd.conf configuration file if the DNS server you want your clients to use has an IP address of 10.11.12.1? ________________________________________________________
10.	You add a new workstation to your /etc/dhcpd.conf file. You're in a hurry to finish, so you save and go to lunch. When you return, your phone mail is full of user complaints that they can't access the Internet, but the local network is fine. You surmise that you accidentally changed something in the dhcpd.conf file. What directive should you look at first in dhcpd.conf? ________________________________________________________

Answers

9.	If the DNS server you want your clients to use has an IP address of 10.11.12.1, add the domain-name-servers 10.11.12.1; directive to your /etc/dhcpd.conf configuration file.
10.	A missing routers directive in /etc/dhcpd.conf would keep your hosts from getting the gateway address, which is required to access the Internet from an internal network.

The Network Time Protocol

11.	From the /etc/ntp.conf file, there's the following directive: restrict default kod nomodify notrap nopeer noquery What directive would you add to open access to the 192.168.0.0/24 network? ________________________________________________________
12.	What Web site is associated with the public NTP server project? ________________________________________________________

Answers

11.	The appropriate directive that limits access to the 192.168.0.0/24 network is restrict 192.168.0.0 mask 255.255.255.0 nomodify notrap
12.	Pool.ntp.org is the Web site associated with the Public Time Server project. If you've used the Date/Time Properties tool, you should be familiar with this from the Red Hat defaults.