Concerns about Citrix NetScaler Web Application Firewall (WAF)


Let’s talk about a WAF, a Web Application Firewall on a Citrix NetScaler. What’s to be concerned off? Is it worth while considering a NetScaler to be your WAF? I do work for several companies, including Citrix Consulting Services. Recently I worked on some Web Application Firewall projects, so I have some experience on it. Usual concerns will a Citrix NetScaler be really safe WAF? How...

Logging more detailed data about websites blocked by NetScaler Web Application Firewall (WAF)


last update: April 16th 2018 I had been asked recently: Johannes, how can we log data about NetScaler Application Firewall policy hits in detail? The standard NetScaler Web Application Firewall log-files NetScaler’s Web Application Firewall logs to /var/log/ns.log. These logs are fine for trouble shooting. There is a good description about these logs here. This is a sample log, stolen from...

DDOS protection using Citrix NetScaler, 2nd part


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...

DDOS protection using Citrix NetScaler, 1st part


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...

What’s in a WAF (Web application firewall)


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...

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