Securities Software (Network Services).Linux OpenSSH Client/Server
Overview
As illustrated in Chapter 2, “Installation of your Linux Server”, many network services including, but not limited, to telnet, rsh, rlogin, or rexec are vulnerable to electronic eavesdropping. As a consequence, anyone who has access to any machine connected to the network can listen in on their communication and get your password, as well as any other private information that goes over the network in plain text. Currently the Telnet program is indispensable for daily administration task, but is insecure since it transmits your password in plain text over the network and allows any listener to thereby use your account to do any evil he likes. (Далее…)
Linux PortSentry
Overview
Firewalls help us to protect our network for unsolicited intrusions. With them we choose which ports we want to open and which ones we don’t. Information is kept private by your organization and responsibility. Nobody from the outside knows implicitly knows this information, but attackers know as well as spammers that for some kinds of attacks you can use a special program to scan all the ports on a server to glean this valuable information (what is open and what is not). (Далее…)
Linux Logcheck
Overview
One important task in the security world is to regularly check the log files. Often the daily activities of an administrator don’t allow him the time to do this task and this can bring about problems. (Далее…)
Securities Software (Monitoring Tools).Linux sXid
Overview
SUID/SGID files can be a security hazard. To reduce the risks, we have previously already removed the ’s’ bits from root-owned programs that won’t absolutely require such privilege, but future and existing files may be set with these ’s’ bits enabled without your notification. sXid is an all in one suid/sgid monitoring program designed to be run from cron on a regular basis. Basically it tracks any changes in your s[ug]id files and folders. (Далее…)
Some last comments
Before proceeding to read the rest of this book, it should be noted that the text assumes that certain files are placed in certain directories. Where they have been specified, the conventions we adopt here for locating these files are those of the Red Hat Linux distribution. If you are using a distribution of Linux (or some other operating system) that chooses to distribute these files in a different way, you should be careful when copying examples directly from the text. (Далее…)