On October 15, 2017, security researcher Mathy Vanhoef announced the discovery of KrackAttacks, a serious flaw in the WPA2 encryption protocol that encrypts most WiFi connections. Using this method, an attacker can decrypt traffic from almost any wireless access point (WAP) and clients. Every WiFi access point will need to be upgraded with patch that prevents … Continue reading Upgrade Ubiquiti UniFi Access Points (WAP) now to avoid KrackAttack
When you run yum upgrade on a CentOS/RedHat 7 instance, you will be upgraded to 7.4. If you have a FreeRADIUS server, you will be upgraded from version 2 to 3, and your server will likely stop authenticating! Good times! Fortunately, the solution was not complicated for us, because we had good documentation. Symptoms Your … Continue reading Warning: CentOS/RedHat 7.4 installs FreeRADIUS 3 with breaking changes
It can confusing when you have multiple persistent disks on an instance running on Google Compute Engine. For example, a server may have separate disks for the filesystem root, MySQL data, logs, and /tmp. Once you've created the Compute Engine disks and attached each one to the instance, how do you know which Compute Engine … Continue reading Managing persistent disks on Google Compute Engine
The Historical Answer With Windows NT, prior to the advent of Active Directory, there was one Primary Domain Controller (DC) per domain, and every other DC was a Backup. The Modern Answer When Active Directory was introduced with Windows 2000, domain controllers became fully multi-master. There is no primary domain controller. However, there are two … Continue reading Is there a “Primary Domain Controller” in Active Directory?
If you are a Linux or OS X power user, then you're used to having all the necessary tools built into your OS. When you log into a Windows system (What! No command line?) you may feel lost. These tools and shortcuts will help you be productive on Windows systems. Windows Shortcuts Alt-x is a … Continue reading Making Windows work for Linux and OS X admins
In Part 1, I summarized the basic concepts of SNMP and defined the terms and acronyms used in this post. Now, I will show how to use SNMP to monitor actual devices. As an example, I will monitor an enterprise-grade uninterruptible power supply (UPS) and power distribution unit (PDUs) from Tripp-Lite. These devices have an … Continue reading Monitoring with SNMP, Part 2: Command-line tools for active SNMP
SNMP is a protocol for conveying information and controlling devices over a network. SNMP can be used in two ways: Active: a device sends a command to set a parameter or request information for another device Passive: a device sends an alert (called a trap) to another device, which is configured to receive traps and … Continue reading Monitoring with SNMP, Part 1: Fundamentals of SNMP