This is only a short blog post to document a solution for a very annoying problem. After the automatic update of my Outlook to the latest Office 365 build (version 1809), it has started to prompting for credentials. I’m using Outlook to access a Microsoft Exchange 2016 server (on-premises), without any hybrid configuration. A pretty simple and plain Exchange 2016 on-prem deployment.
I knew, that it has to be related to Office 365, because the Outlook 2016 on my PC at the office was not affected.
It is common that vendors offer their products in special editions for SMB customers. VMware offers VMware vSphere Essentials and Essentials Plus, Veeam offers Veeam Backup Essentials, and now Vembu has published Vembu BDR Essentials.
Vembu Technologies/ Vembu BDR Essentials/ Copyright by Vembu Technologies
Backup is important. There is no reason to have no backup. According to an infographic published by Clutch Research at the World Backup Day 2017, 60% of all SMBs that lost all their data will shutdown within 6 months after the data loss.
TL;DR: I have passed the VCAP6-DCV Deploy exam today. :) I want to thank Fred, Dominik, Frank and Jens-Henrik for kicking my ass. Without you, I would have taken the VCP 6.5 delta exam. Thank you!
As often, the whole thing started with a tweet. A tweet about my expiring VMware Certified Professional (VCP) certification.
Time to prepare the VCP-DCV 6.5 Delta. Otherwise my VCP expires in a couple of months.
When taking a backup with Veeam Backup & Replication, a VM snapshot is created to get a consistent state of the VM. The snapshot is taken prior the backup, and it is removed after the successful backup of the VM. The snapshot grows during its lifetime, and you should keep in mind, that you need some free space in the datastore for snapshots. This can be a problem, especially in case of multiple VM backups at a time, and if the VMs share the same datastore.
I have worked with a lot of backup software products during my career, but for the last years I have primarily worked with MicroFocus Data Protector (former HP OmniBack, HP Data Protector, or HPE Data Protector), and Veeam Backup & Replication. Data Protector was a great solution for traditional server environments, or when UNIX (HP-UX, AIX, Solaris etc.) compatibility was required. Features like Zero Downtime Backups, LAN-free or Direct SAN backups were available for many years.
In January 2017, I wrote an article about how to protect your Wordpress blog using the WP Fail2Ban plugin, fail2ban on your Linux/ FreeBSD host, and CloudFlare. Back then, the fail2ban was using the CloudFlare API V1, which was already deprecated since November 2016.
Although the actions were updated later to use CloudFlare API V4, I still had problems with the unbaning of IP addresses. IP addresses were banned, but the unban action failed.
This is just a short, but interesting blog post. When you have to troubleshoot authentication failures in a network that uses Windows Network Policy Server (NPS), the Windows event log is absolutely indispensable. The event log offers everything you need. The success and failure event log entries include all necessary information to get you back on track. If failure events would be logged…
Today, I was playing with Alcatel-Lucent Enterprise OmniSwitches and Access Guardian in my lab.
Sometimes you have to replace SSL certificates instead of updating them, e.g. if you switch from a web server SSL certificate to a wildcard certificate. The latter was my job today. In my case, the SSL certificate was used in a Microsoft Exchange 2016 deployment, and the NetScaler configuration was using multiple virtual servers. I’m using this little script for my NetScaler/ Exchange deployments.
When using multiple virtual servers, replacing a SSL certificate using the GUI can be challenging, because you have to navigate multiple sites, click here, click there etc.
Usually, bypassing a firewall is not the best idea. But sometimes you have to. One case, where you want to bypass a firewall, is asymmetric routing.
What is asymmetric routing? Imagine a scenario with two routers on the same network. One router offeres access to the internet, the other router provides access to other sites with site-2-site VPN tunnels.
Patrick Terlisten/ vcloudnine.de/ Creative Commons CC0
Host 1 uses R1 as default gateway.
Last week I had an interesting incident at a customer. The customer reported that one of multiple Veeam backup jobs jobs constantly failed.
The backup job included two VMs, and the backup of one of these VMs failed with this error:
Error: Failed to open VDDK disk [[VMDS-SAS-01] VMDC1/VMDC1_1.vmdk] ( is read-only mode - [true] ) Failed to open virtual disk Logon attempt with parameters [VC/ESX: [vcenter.domain.tld];Port: 443;Login: [ADAdministrator];VMX Spec: [moref=vm-59];Snapshot mor: [snapshot-20226];Transports: [san];Read Only: [true]] failed because of the following errors: Failed to open virtual disk Logon attempt with parameters VC/ESX: [vcenter.
