Advice for everyday Unix systems administration and some clever ways to approach more challenging problems.
The security dudes have been badmouthing telnet for a couple of decades now, reminding us that this old time tool for connecting to remote systems exposes our passwords to the snooping masses. But the telnet command itself still has some handy uses t....
The grep command can search for and list Linux files based on strings you are looking for and add the context of surrounding text.
The /etc/inittab file controls what happens whenever a Unix system is rebooted or forced to change run levels. Let's take a look at the configuration lines that tell your system what it's supposed to do when you hit that power button.
Port knocking is a method of opening ports on a firewall by trying to connect with a series of ports in a pre-determined order. The sequence of “knocks” acts like a secret access code
Whenever you use a simple grep command to find a single word or phrase in a file, you run the risk of getting a lot of extra "stuff" you didn't want to see. Here are two grep commands that will do just what you want.
The /etc/acct/holidays file is intended to be used by various accounting utilities on your system that might need to behave differently on certain days of the year -- holidays.
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