Category: Linux and UNIX

A few months ago we had Daylight Savings Time. My parents were delighted to discover that “the clock” in their car automatically adjusted itself, as did their computer. But now they had to change the two clocks in their bedroom, the two clocks in the kitchen, and several others around the house. How did the […]

The big cybersecurity news of the past couple of weeks has been the WannaCry worm. It took advantage of some rather old bugs, dating back to Windows XP and Windows Server 2003. We got lucky! The vulnerability, the problems in the targets, allowed unlimited abuse. But the exploit, the attackers’ code, had a built-in “kill […]

Perfect is the enemy of good. That’s an old saying. Confucius (551-479 BC) said, “Better a diamond with a flaw than a pebble without.” Aristotle (384-322 BC) said something similar. Voltaire popularized the phrase in the 1770s. And maybe that’s where we are with SDN WAN. Software-Defined Networking and Wide Area Network Links Software-defined networking, […]

Do you know how to check the IP address of a Linux server? “Of course!”, you say, and you type this: $ ifconfig eth0 Not anymore! Both the command ifconfig and the interface name eth0 have been obsolete for a few years now. However, many organizations still use something like Red Hat Enterprise Linux 6, […]

Recently, I posted about basic permissions for Linux files; now let’s look at how to access those in a shell script. Testing file permissions is an essential part of enforcing an access control policy. Two common ways to test files for readability, writability, zero size and so forth are the if and the test. For […]