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Frequently Asked Questions About F5 Technology

F5 is the creator of and home to many different, powerful technologies. We offer some of the most powerful, advanced application delivery technology in the world. As with any advanced technology, however, there are often times terms and names... Read more
0 Reviews

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

DevCentral Architecture

Everyone has surely (don’t call me Shirley!) at least been exposed to THE CLOUD by now.  Whether it’s the—I’ll go with interesting—“to the cloud!” commercials or down in the nuts and bolts of hypervisors and programmatic interfaces for... Read more
1 Review

iRules logging to multiple locations with ease

Some months back I was at an account where we were developing some iRules to provide logging detail. One of the complications was that some of the infrastructure to support remote logging was in the process of being implemented and was not... Read more
1 Review

iRules Concepts: Logging, a Deeper Understanding

Multiple times in recent iRules presentations, whether on the road or here within F5, there have been questions raised when the topic of logging within iRules gets brought up. Specifically people are curious about logging best practices,... Read more
0 Reviews

Redirects, Rewrites and App Transfers via iRules

While traveling and talking about iRules, I come across a wide variety of topics that people are looking to address. From security offload to custom routing to just about anything you can think of. This week, while out and about at User Groups, I... Read more
2 Reviews

Vulnerability Patching via iRules: VU#520827 for PHP

Security is a top level priority in nearly every IT infrastructure these days. Whether it's keeping server patching up to date, putting in place hardened firewalls, password security models, denial of service prevention or any of the other... Read more
0 Reviews

iRules Concepts: Tcl, The How and Why

F5 uses Tcl as the interpreter for iRules. Many people often ask why that is. This questions is usually followed up by an immediate, "Why not Perl?" or "Why not Java" or "Why not ?". I understand the question, and... Read more
Average Rating: 4.5
5 Reviews

v11: iRules Data Group Updates

Several months ago I wrote up the v10 formatting for internal and external datagroups: iRules Data Group Formatting Rules. In v11, however, there is a change to the format of the internal data group and the data group reference to external class... Read more
Average Rating: 4.6
11 Reviews

HTTP Request Cloning via iRules, Part 1

One of the requests that I've seen several times over the years is the ability to completely clone web requests across multiple servers. The idea is that you can take the HTTP traffic coming in bound for pool member A and distribute it, in its... Read more
1 Review

iRules Concepts: Connection States and Command Suspension

Within iRules, in addition to mastering the language syntax and tricks therein, there is an added layer of understanding that can help in taking your iRules fu to a whole new level. Connection State. Connection states are relatively simple i... Read more
Average Rating: 4.9
3 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

v11.1–Add Signatures or Checksums to iRules via an iApp

iApps, introduced in v11, have a primary function in controlling the object creation and management for an application delivered by BIG-IP. As discussed previously, however, anything that can be accomplished in TMSH can be done in an iApp, so wha... Read more
1 Review

v11.1–External File Access from iRules via iFiles

New in BIG-IP version 11.1 are iFiles, a feature that allows users to load files through tmsh or the GUI onto the BIG-IP which can be referenced from iRules. This has an immediate use case of supplanting several of our codeshare entries for sorr... Read more
Average Rating: 4.9
8 Reviews

Base32 Encoding and Decoding With iRules

Introduction Anyone that's done any amount of programming has probably encountered Base64 encoded data. Data that is encoded with Base64 has the advantage of being composed of 64 ASCII characters, which makes it portable and readable with... Read more
0 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

APM Session Invalidation Using ASM

Introduction: Whenever customers expose their internal resources on the Web using VPNs or SSL VPNS there is still some concern over what type of traffic comes through the connection. In order to assist with these concerns we can provide a combine... Read more
Average Rating: 4.9
3 Reviews

Create a User Lockout Policy with Access Policy Manager

This article will cover a simple access policy that when completed will lock out a user using BIG-IP Access Policy Manager.  Start by making an access policy with the Device Wizard. Since I just want to make a quick and easy example, I’ll b... Read more
0 Reviews

Preventing Brute Force Password Guessing Attacks with APM–Part 4

F5er and DevCentral community member ystephie is back with another great solution (check out her first solution here: BIG-IP APM Customized Logon Page), this time tackling brute force attacks utilizing customizations with the BIG-IP Access Polic... Read more
2 Reviews

Preventing Brute Force Password Guessing Attacks with APM–Part 3

F5er and DevCentral community member ystephie is back with another great solution (check out her first solution here: BIG-IP APM Customized Logon Page), this time tackling brute force attacks utilizing customizations with the BIG-IP Access Polic... Read more
1 Review

Cookie Persistence and Troubleshooting

The BIG-IP persistence cookie is a valuable configuration option that allows stateful applications to remain persistent to a specific node with no additional configurations within the application or on the server(s) by doing something lik... Read more
2 Reviews

iRules Concepts: Considering Context part 2

In part 1 of this brief series we talked about what context means while coding, how it affects our perception of things and the different contexts within iRules that are inherent and would be covered in this 2 part-er. As a refresher, those... Read more
0 Reviews

iRules Concepts: Considering Context part 1

Language is a funny thing. It's so easily misunderstood, despite the many rules in place to govern its use. This is in part, of course, due to dialects and slang, but context shouldn't be underestimated as an important piece o... Read more
0 Reviews

BIG-IP APM–Customized Logon Page

Note: This solution is only applicable to version 10.x, version 11 doesn't use advCustHelp. The default logon page for the Access Policy Manager module is pretty basic, particularly so if only the minimal username and password ... Read more
Average Rating: 4.4
11 Reviews

iRules 101–#18–Revisiting the TCL Scan Command

I covered the Tcl scan command back in the iRules 101 – #16 – Parsing Strings with the TCL Scan Command, but this example (by Hoolio, who else?) was too good not to share with the community. The request involved parsing a log entry as efficientl... Read more
1 Review