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Security Irules 101: DNS Gravitational Disturbance

Introduction iRules are a powerful tool in the F5 administrators arsenal. They allow administrators to adapt and customize the F5 to their needs. They provide extensive power for security engineers as well. We’ve decided it’s time to revisit... Read more
1 Review

Building a resilient, secure DNS infrastructure.

DNS is inherently insecure and exposed. F5 customers have been seeing a spate of DNS attacks and DNS denial of service lately, and I thought it would be a good idea to analyze a few of the common attack vectors, and ways F5s GTM, or LTM DNS... Read more
0 Reviews

v11.1: DNS Blackhole with iRules

Back in October, I attended a Security B-Sides event in Jefferson City (review here). One of the presenters (@bethayoung) talked about poisoning the internal DNS intentionally for known purveyors of all things bad. I indicated in my write-up tha... Read more
Average Rating: 4.9
3 Reviews

DNS Services Architecture

F5 has been in the DNS business for quite some time, beginning with the 3-DNS GSLB product introduced in 1998. While steadily growing the GSLB market through product advances, the platform is incredibly feature rich now, offering far more than... Read more
Average Rating: 4.9
6 Reviews

DNS Resolution via iRules: NAME::lookup vs RESOLV::lookup

There are so many things that you can do with iRules that it can be pretty staggering to narrow down what the "most useful" commands are, but if I were given that task and absolutely had to, I would say that DNS resolution ranks up there... Read more
Average Rating: 4.9
3 Reviews

v11: DNS Express – Part 2

Introduction In our last Tech Tip, v11: DNS Express – Part 1, we discussed configuring DNS Express as an authoritative slave DNS server. We also discussed the advantages of using DNS Express in place of a pool of BIND servers. In this part of... Read more
0 Reviews

v11: DNS Express – Part 1

Introduction Among the many features released with GTM version 11, DNS Express has to be near the top of the list for many DNS administrators. DNS Express is a high performance in-memory authoritative DNS server. GTM has always been able to serve... Read more
0 Reviews

Dynamic Pool Member Selection Via DNS

Ponder this scenario, you have built a worldwide CDN with WebAccelerator and GTM. You have tens if not hundreds of remote WebAccelerators and multiple central datacenters housing your central WebAccelerators and origin servers. Only one central... Read more
0 Reviews

v10.1 - Configuring GTM's DNS Security Extensions

Security extensions were added to the DNS protocol as a means of countering malicious attacks such as cache poisoning, domain hijacking, and man-in-the-middle attacks.  The extensions are described in detail in RFC 4033 (Introduction an... Read more
0 Reviews

Selective DNS Persistence on GTM

The world of DNS is an interesting one to me. So much of what transpires on the internet these days relies on it, heavily, to connect from point A to B with ease, and yet it remains relatively unchanged, compared to the more complex and rapidly... Read more
1 Review

Non-English DNS Request filtering via iRules

When talking about iRules there are many themes that come up: application fluency, flexibility, control, high-availability. Among the themes that are often related to iRules one of the most important, in my estimation, is the extremely granular... Read more
0 Reviews