In the latest versions of Citrix NetScaler ADC, the dig command is missing. Where did it disappear to and why? The reason is relatively simple: recent versions of BSD from version 10 do not support dig anymore, it has been replaced by drill. The good thing is that drill has almost the same functions and parameters as dig, so you just have to replace dig with drill. The current Citrix NetScaler...
Recently, I came across a question: When did the STA go down? How can we find out? Well, that’s easy to tell, as it gets logged. Unfortunately, the log isn’t that easy to understand. And, of course, like all logs in Citrix NetScaler, it disappears in a bit more than a day due to logfile rollover. Where do we search for these logs? Like always, my first source is Syslog. In a...
Notepad++ is widely used by Windows administrators. The reason is, Notepad++ is not just a good editor, it also allows to “understand” different languages, like HTML, CSS, Java, Pearl and many more. My friend and fellow CCI (Citrix trainer) at that time, Christian Schwendemann (now Citrix employee), created NetScaler definitions for Notepad++. He sent it to me, but I found several...
Usually, we create profiles in a test environment. After thoughtful testing, we have to copy them to the production and the DR site. Requirements: Test, production and DR site have to be exactly the same version, or the import will fail. The user has to be able to use the shell (so it has to be equivalent to nsroot) Exporting a profile The profile can get exported at any time. This can be done...
No doubt, monitoring a WAF is an important thing to do. It helps to find attacks and their sources for forensic purposes and is needed to find false positives as well. How to do it? Citrix NetScaler WAF logs locally, that’s great for real-time logging and trouble shooting, but it may also log to external sources like Citrix Application Delivery Manager (ADM), that’s great for long...
Sometimes, we need specific attributes like an E-Mail address or the userPrincipalName to be passed from a SAML IDP to the SP. If you use a Citrix ADC / NetScaler as SAML IDP, it is, indeed, an easy thing to do. Let’s have a look. Extracting attributes from LDAP The first step, of course, is always to retrieve an attribute from LDAP. This is done via an LDAP policy. I won’t go into...
last updated: April 26 2022 I am currently creating a slide deck for a CUGC event on May 11. It will be about securing Citrix (NetScaler) Gateway. During my work, I wanted to find out, what the cookie NSC_VPNERR is good for. After a successful login, its value is set to 3 (Citrix ADC 13.0, it’s not documented). With most of the current browsers, you have to press F12 to see the...
last update: July 12th 2022 If someone makes a typing error when entering the domain name, he will not get a valid response. This is a typical example: You can clearly see: The response got an NXDOMAIN status, a non-existing domain. This, however, is not always desired, instead, you might want to return an IP address. It should have looked like this: This time, you see an answer section. The IP...
last update: March 2023 There is a question coming up every now and then: How to extend space on a Citrix ADC formerly called NetScaler. First of all: There is absolutely no supported way to do so! With this in mind, we can continue. Is there a real need to extend the disk space? The answer is no. There is plenty of space for all needs. You said, there is space enough, why did I run out of...
Last update: December 22nd 2021 Many of us, today, struggle with the Log4J security issue (CVE-2021-44228). It will take a long time to fix all apps, as the Apache log4J framework is built deep into several apps. For many of my customer’s apps, it’s still not clear, if whether they are affected, or not. At the same time, there are already exploits out there, allowing attackers to get shell access...