Last update: May 8th 2023 There are several use cases for geo-location information in Citrix ADC / NetScaler. It may be helpful with WAF logs. I am European, I won’t spend much time on a positive, if the log comes from North Korea, but I would consider it to be a “false positive”, if it comes from Germany, Italy or Sweden. Even though I would not consider it to be secure...
The way we create certificates has not changed significantly over the years. Only the wizard is subject to a certain change. This blog is based on Citrix ADC 13, elder versions don’t differ significantly. The following steps are necessary to create a certificate: Generate the key pair Create the certificate-signing request Generate the certificate (either using Citrix ADC /...
last update: March 2nd 2020 Well, there are many guides. So why do I write a blog about it? Just to have one more? Bull shit! The truth is: I don’t like them at all! What’s wrong about all these guides? They all focus on how to remove malware currently installed on our Citrix ADCs (NetScalers). And, to be honest, it does not make the least little bit of sense. How can you ever be 100%...
This is the forth part of this blog. Part Part 1 2 3 4 5 Click here to see how to start your WAF project StartURLs are a powerful tool to protect a web server. Probably, creating StartURLs will be the first thing you need to do. There are two ways to deal with it: Learning or doing. Learning Learning does not mean, you learn, instead Citrix ADC / NetScaler learns about the application. There is...
This is the second part of this blog. Part 1 2 3 4 5 Click here to see how to start your WAF project Signatures Make sure, signatures get updated automatically. Today (January 22 2020) we have version 40. Check the auto update settings. Check, if Signatures Auto Update is enabled and Click on “Check URL”. This will connect to the update server and see the current version of signatures...
This is the forth part of this blog. Part Part 1 2 3 4 5 I am currently working on a Citrix ADC (NetScaler) WAF project. It’s a big international enterprise, security is of some concern to them. So everything hould be pretty much straight forward? Well, it never is. So, how to begin? Well, I almost forgot to mention: I have to introduce myself to the customer. “Hi, I’m Johannes...
Recently a friend asked a question: How is it possible to bypass a responder policy. They knew it happened, but they could not reproduce. HTML- Encoding HTML Encoding is a stupid trick, used by hackers ever since. Any character may get encoded using a encoding table. So instead of using you might use something like . This is strictly following standards. No one does, as it is huge overhead, but...
Yesterday I upgraded to NetScaler 13 built 41.20. Everything worked fine. No problems. But out of a sudden, my Exchange deployment failed to authenticate (I did it following Julian Mooren’s outstanding deployment guide). I did some further investigation and found all my other AAA servers don’t authenticate, even though the outcome of authentication requests was positive. I always saw...
last update: September 25th 2019 I was recently asked: Johannes, is it possible to orun the same AAA server, from the inside with single factor, from the outside with two factor authentication? Of course it is. That’s how you do: Prerequisites My test environment contains of a lb vServer (lb_vsrv_colors). I created a AAA vServer aaa_multifactor_ath. There is a content switching vServer...
photo by geralt (pixabay.com) last update: January 5th 2020 Recently I had to find a solution to block all connections to a TCP based service (SSH, TCP port 22), except of connections from IP addresses that pr-eauthenticated using a AAA vServer. This is something, most firewalls can do, but a Citrix ADC / NetScaler can’t. Ok, it can do, or would you think, I’ll write a blog about me failing...