Certification Summary

Networking services are an integral part of Red Hat Enterprise Linux. While most network services have been covered in other chapters, a few just don't fit neatly into other categories. Some are controlled through the xinetd daemon. SSH and DHCP are two other network services.

The Extended Internet Services Daemon, xinetd, governs the services configured though the /etc/xinetd.d directory. It controls services such as rsync, gssftp, and krb5-telnet, when installed.

Any network that is connected to an insecure network such as the Internet is vulnerable. Older protocols such as Telnet allowed passwords in clear text, which can be easily captured with tools such as Wireshark. The OpenSSH server can help you set up encrypted communication between computers.

DHCP allows a network administrator to manage IP address assignments of the computers on a LAN from a centralized server. DHCP requires some specialized setup on both the client and the server; however, it is easy to maintain once it is configured.

NTP services support time synchronization, which can keep changes such as moving to backup servers, load balancing, logs, and more, seamless to the end user. Clients can be configured with the Date/Time configuration tool or in /etc/ntp.conf. Configuring an NTP server requires specialized settings in /etc/ntp.conf.