In this chapter, we covered a wide array of security features that are available to us in the Linux environment. First, we covered accessing commands with root privileges; particularly, we looked at the su and sudo commands. We then moved on to TCP wrappers, focusing on the /etc/hosts.allow and /etc/hosts.deny files. We looked at how the two files can complement each other by allowing access via the /etc/hosts.allow file and denying everything in the /etc/hosts.deny file.
Next, we covered SSH; we looked at setting up SSH access between a client and a server, allowing for a seamless login without entering a password, and we covered using a passphrase. We then cached the passphrase, so that the user would not have to enter a passphrase when logging into the server. Finally, we covered encryption in depth. We focused on symmetric encryption, which involves a passphrase; we...