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.
Benefit of storage snapshots
If your underlying storage supports the creation of storage snapshots, Veeam offers an additional way to create a consistent state of the VMs.… Read more
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 the unban action, which is included in fail2ban (taken from fail2ban-0.10.3.1 which is shipped with FreeBSD 11.1-RELEASE-p10):
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. Access Guardian refers to the some OmniSwitch security functions that work together to provide a dynamic, proactive network security solution:
Universal Network Profile (UNP)
Authentication, Authorization, and Accounting (AAA)
Bring Your Own Device (BYOD)
Quarantine Manager and Remediation (QMR)
I have planned to publish some blog posts about Access Guardian in the future, because it is a pretty interesting topic.… Read more
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. Using the CLI, the same task is much easier und faster.… Read more
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.
Host 1 uses R1 as default gateway. R1 has static routes configured to the networks reachable over the VPN, or it has learned them dynamically using a routing protocol from R2. A packet from host 1 arrives at R1, is routed to R2, and is sent over the VPN tunnel.… Read more
The last two days, I have supported a customer during the implementation of 802.1x. His network consisted of HPE/ Aruba and some HPE Comware switches. Two RADIUS server with appropriate policies was already in place. The configuration and test with the ProVision based switches was pretty simple. The Comware based switches, in this case OfficeConnect 1920, made me more headache.
The customer had already mac authentication running, so all I had to do, was to enable 802.1x on the desired ports of the OfficeConnect 1920. The laptop, which I used to test the connection, was already configured and worked flawless if I plugged it into a 802.1x enabled port on a ProVision based switch.… Read more
During the replacement of some VMware ESXi hosts at a customer, I discovered a recurrent failure of the vSphere Distributed Switch health checks. A VLAN and MTU mismatch was reported. On the physical side, the ESXi hosts were connected to two HPE 5820 switches, that were configured as an IRF stack. Inside the VMware bubble, the hosts were sharing a vSphere Distributed Switch.
The switch ports of the old ESXi hosts were configured as Hybrid ports. The switch ports of the new hosts were configured as Trunk ports, to streamline the switch and port configuration.
Some words about port types
Comware knows three different port types:
If you were familiar with Cisco, you will know Access and Trunk ports.… Read more
By accident, I found a heartbeat/ VLAN issue on a NetScaler cluster at one of my customers. The NetScaler ADC appliances have three interfaces connected to a switch stack. Two of the three interfaces were configured as a channel (LAG). This is a snippet from the config:
set channel LA/1 -tagall ON -throughput 0 -lrMinThroughput 0 -bandwidthHigh 0 -bandwidthNormal 0