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Security Irules 101: You can’t always get what you want.. or can you?

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 tim... Read more
Average Rating: 4.9
3 Reviews


Denial of Service (DoS) attacks have been around for many years, but they are still frequently used today (ref: Iran's recent fascination with the US banking industry).  These attacks are used against servers to disrupt legitimate... Read more
1 Review

Getting Started with Bigsuds–a New Python Library for iControl

I imagine the progression for you, the reader, will be something like this in the first six- or seven-hundred milliseconds after reading the title: Oh cool! Wait, what? Don’t we already have like two libraries for python? Really, a third library... Read more
Average Rating: 4.6
10 Reviews

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

8.3 Alternate Names With ARX

Summary 8.3 names are a relic of the 1980’s, when the FAT12 and FAT16 file systems used in MS-DOS did not have a provision for arbitrarily-long filenames. In those days, names could have at most eight characters, followed by a single period, and... Read more
0 Reviews

Managing Ramcache Entries with Pycontrol

A DevCentral user posted a question in the forums asking for verification of an attribute on the RamCacheKey structure. The maximum_responses attribute should be a long integer. With his C# code, the maximum_responses returned from his iContro... Read more
0 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

Implementing The Exponential Backoff Algorithm To Thwart Dictionary Attacks

Introduction Recently there was a forum post regarding using the exponential backoff algorithm to prevent or at the very least slow down dictionary attacks. A dictionary attack is when a perpetrator attacks a weak system or application by cyclin... Read more
0 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

v11 iControl: Transactions

Introduction One of the most commonly requested features for iControl we’ve seen recently has been for transaction support. It was implemented in TMSH for Version 10 and is now available for iControl in Version 11. Transactions are super handy... Read more
2 Reviews

Ruby and iControl: Migrating Virtual Addresses Using ARP

Introduction Ever wanted to “failover” a virtual server to an LTM that is not part of the same HA (high availability) pair? This is a common occurrence for any engineer that has ever had to upgrade their BIG-IP hardware platform or been part of a... Read more
0 Reviews

Creating A File Criteria To Find Characters Not Supported In A CIFS File System

Introduction This article illustrates how to create a file criteria directly through the ‘Criteria Wizard’ as well as by uploading a text file that contains the criteria. As an example we will create a criteria that will identify file names that... Read more
0 Reviews

Automating Web App Deployments with Opscode Chef and iControl

Chef is a systems integration framework developed here in Seattle by Opscode. It provides a number of configuration management facilities for deploying systems rapidly and consistently. For instance, if you want 150 web servers configur... Read more
2 Reviews

Multiple Certs, One VIP: TLS Server Name Indication via iRules

An age old question that we’ve seen time and time again in the iRules forums here on DevCentral is “How can I use iRules to manage multiple SSL certs on one VIP"?”. The answer has always historically been “I’m sorry, you can’t.”. The... Read more
0 Reviews

Ruby and iControl: Automating Private Key and Certificate Signing Request Creation

Overview If you’re like most of our customers, you’re probably offloading SSL on your BIG-IPs. There is a large performance benefit to this PKI management strategy, but there is also the simplicity of being able to create, update, and manage SSL... Read more
0 Reviews

Ruby and iControl: Building A Maintenance Page iRule On The Fly

Overview This week we are continuing with our Ruby and iControl series, but we’re going to mix in some iRule spice. As a previous IT systems engineer here at F5 as well as startups, it is a common request to shunt a site to a maintenance page... Read more
0 Reviews

Ruby and iControl: Distilling SSL Certificate Information from SOAP::Mapping::Objects

We hope by now that you have gotten a running start with our Ruby iControl libraries. We have posted a few other Tech Tips on Ruby and iControl,  but have not touched on the retrieval of information from the BIG-IP. In this Tech Tip, we will... Read more
0 Reviews

Client Cert Fingerprint Matching via iRules

Client cert authentication is not a new concept on DevCentral, it’s something that has been covered before in the forums, wikis and Tech Tips.  Generally speaking it means that you’re receiving a request from a client, and want to... Read more
0 Reviews

Ruby and iControl: Understanding Complex Type Syntax

Anyone who has worked with SOAP knows it can make a lot of things easier, but it is not without its hurdles. Interpreting complex type syntax for use with a SOAP driver can present one of the largest headaches for a web services developer. In this... Read more
0 Reviews

Getting Started With Ruby and iControl

Here on DevCentral we’ve released libraries for a number of the big languages from Java and Perl to Powershell. Up until now there has not been much love for Ruby. Well, that’s all about to change: enter the new iControl Ruby Library. This proj... Read more
2 Reviews

Pacfiles R iRules?

by Bhattman @ gmail dot com   Pac Files are used throughout various companies to direct traffic out proxy systems but is not well understood by most and how it relates to F5 ADCs.  Hopefully this article can clear it up for you and giv... Read more
0 Reviews

Trending BIG-IP With Munin

Munin is an RRDtool-based (Round Robin Database Tool) graphical trending application. The server portion runs on Unix-like machines and the client portion runs on a number of different platforms and architectures. Munin is based on RRDtool, which... Read more
0 Reviews

Give me your query, your header and your failed

by Bhattman at gmail.com   The title sounds like a movie title. Actually its more related to the next scenario which I thought was unique enough to write about.  Recently a client came to me to discuss a problem she wanted solved by an... Read more
0 Reviews

Self-Contained BIG-IP Provisioning with iRules and pyControl - Part 1

There’s a plethora (yes, a plethora.  The Three Amigos taught me well.) of quality information constantly flowing here at DevCentral.  And whereas I might not have El Guapo’s superior intellect, I do have enough smarts to lean on my man... Read more
0 Reviews