What’s an IP address calculator? I’m pretty sure it’s something you won’t need. It will help understanding IP addresses. It does calculations on IP addresses and will tell you, if the address is valid (or a network / broadcast address), and if two addresses are on the same subnet. Why did I create an IP address calculator like that? My daughter started studying informatics...
Last update: 2018/03/27 Sometimes we have to schedule commands in a Citrix NetScaler. A good example would be: force HA failover It’s obvious, we don’t want to fail over during day time to not disconnect TCP connections, to not interrupt users. The best time would be something like 3:30 AM. It’s obvious, we don’t want to set an alarm for 3:00 to get up, take a shower...
last update: 2018/04/12 I recently had to protect a website using IP reputation feature. There is some good information about this feature, however I decided to glean information here. Facts about this feature IP reputation is a platinum feature. It is included in web application firewall (there are extra licenses for the WAF available, they also contain IP-reputation). IP-reputation feature...
last updated: December 2020 Creating a Citrix NetScaler Test environment New since February 2020: Instead of downloading, you may just use my environment, hosted at my private data centre. Being a Citrix Certified Instructor I am very much aware of the Red/Green/Blue website used during official Citrix NetScaler training (CNS-220, CNS-222). I created my own test website. I usually use it during...
Last update: January 11th 2022 This one is outdated, as the Citrix ADC Version and MAS (former name of ADM) it refers to, is available no more. However, I wrote a new blog on how to enlarge disk space on a Citrix ADC / NetScaler VPX. My NetScaler VPX ran out of disk space. I did several tricks like adding a second disk and mounting ít into the update directors, to be able to upgrade my NetScaler...
last update: October 22nd 2021 Citrix NetScaler Logging and policy troubleshooting Some times it’s quite hard to understand what’s going on. There is a lot of mystics about policies. And it’s even harder to understand what went on (past tense). “Johannes, there had been several problems connecting to <any blabla application here>” “I’m sorry, I...
Why do I love HDX on UDP in Citrix XenDesktop and XenApp? (HDX Enlightened Data Transport EDT) Well, I’m mainly a network guy. So I’ll take a look at this brand new feature from networking perspective.I’ll start from scratch, so I don’t assume you understand network protocols. But let me tell you a joke about UDP first: I got a short joke about UDP, and I don’t care...
Yesterday I published a blog about DDOS- protection. I used the Citrix NetScaler AppQoE feature to do so. That’s nice, but not enough. I still could beat my server to a pulp easily. Just 10 clients launching a DDOS attack using HULK had been enough. I can’t throttle down the number of users to just 10! WTF? Basically AppQoE will just limit the number of users (actually it’s the...
last update: February 21st 2018 How to protect a website using Citrix NetScaler? Well it seems to be easy. A nonsense question. We may use AppQoE (Application level Quality of Experience), a feature introduced with NetScaler version 10, so it’s quite an old feature. Let’s start. AppQoE is enterprise edition My first starting point was E-Docs. Let’s be honest: the guy in charge...
This article is a very first answer to a question I recently received. The question was: You’re talking about web application firewalls. I’d like to know how to use the WAF for reverse proxying. … I also might use a firewall as it also contains functions like SQL injection prevention. So what’s in a web application firewall? A web application firewall, also known as WAF...