BIG-IP Configuration Object Naming Conventions

George posted an excellent blog on hostname nomenclature a while back, but something we haven’t discussed much in this space is a naming convention for the BIG-IP configuration objects. Last week, DevCentral community user Deon posted a question on exactly that. Sometimes there are standards just for the sake of having one, but in most cases, and particularly in this case, having standards is a very good thing. Señor Forum, hoolio, and MVP hamish weighed in with some good advice. [app name]_[protocol]_[object type] Examples: www.example.com_http_vs www.example.com_http_pool ...

Stop that F5 Key From Refreshing the Page

No, not “us” F5, the F5 key on the keyboard. You know, the one you hit relentlessly to refresh the page (well, the one I hit relentlessly during NFL games to update my fantasy football stats). Anyway, I was perusing the forums today, trying to catch up from a week attending our very excellent annual sales conference, and I noticed a thread that had to be shared. The Question Is there a way of preventing users from using the F5 button to refresh a web page? – DevCentral user ringoseagull (nice handle, btw!) ...

So Yeah, Regex is Bad

Don’t get me wrong, regex is awesome, and entirely useful—sometimes it’s the only option, it’s just not the best tool of choice for wire speed applications.  Often the sys-admin and network type converts to BIG-IP will find the regexp tcl command and go that route because it’s familiar.  If that describes you, please let me introduce you to a couple more appropriate commands: scan string These two commands will cover a great percentage of regexp’s use cases, and will save significant resources on the system.  Don’t buy it?  Here’s...

Changing the BIG-IP Default Syslog-NG Facilities

DevCentral community member geffr had a problem. The BIG-IP Application Security Manager module logs to the local3 facility but he needs to send them to the local7 facility on a remote server. Before giving up entirely, he posted to this thread in the Monitoring & Management group forum, where user nitass helped him jump through the syslog-ng hoops (click here for tips & tricks on syslog-ng) to the working solution posted below. It’s pretty straight forward. Define a template, a filter, and a destination, and then put the pieces together in a log statement. ...

BIG-IP Configuration Conversion Scripts

Two of our biggest internal contributors, Kirk Bauer and John Alam, are at it again with a handful of perl scripts aimed at easing your migration from some of the “other guys” to BIG-IP.  While they aren’t going to map every nook and cranny of the configurations to a BIG-IP feature, they will get you well along the way, taking out as much of the human error element as possible.  I built a few pages in the Advanced Design & Configuration wiki to host these scripts. Migrating from Cisco ACE, CSM, or CSS ...

IP::addr and IPv6

Did you know that all address internal to tmm are kept in IPv6 format?  If you’ve written external monitors, I’m guessing you knew this.  In the external monitors, for IPv4 networks the IPv6 “header” is removed with the line: IP=`echo $1 | sed 's/::ffff://'` IPv4 address are stored in what’s called “IPv4-mapped” format. An IPv4-mapped address has its first 80 bits set to zero and the next 16 set to one, followed by the 32 bits of the IPv4 address.  The prefix looks like this: 0000:0000:0000:0000:0000:ffff: (abbreviated as ::ffff:, which looks strickingly simliar—ok, identical—to the pattern...

Microsoft Exchange 2010 iRule Workflow Visualized

F5’s own John Alam sent over his latest Visio creation to share with the DevCentral community.  This diagram details the workflow of the comprehensive exchange services iRule described in the Microsoft Exchange 2010 Deployment Guide. Enjoy. For visio, pdf, png, & svg versions of this image, click here. Related Articles Microsoft Exchange 2010: HELO New Architecture Webcast - Microsoft Exchange Server Availability And Scalability Exchange Persistence Duality and iRules > DevCentral > F5 ... How Microsoft deployed Exchange Server...

Mitigate Java Vulnerability with iRules

I got a request yesterday morning to asking if there was a way to drop HTTP requests if a certain number was referenced in the Accept-Language header.  The user referenced this post on Exploring Binary.  The number, 2.2250738585072012e-308, causes the Java runtime and compiler to go into an infinite loop when converting it to double-precision binary floating-point.  Not good.  Twitter is ablaze on the issue, and there is a good discussion thread on Hacker News as well.  So how do you stop it?  At first, this appeared to be a no-brainer, just copy that string and drop if found in...

iRules Community Spotlight: Same Segment Load Balancing

This has been a perplexing issue for many users.  How do you introduce an intermediary (LTM going forward) between client and server when in the same network segment?  It’s easy when the LTM sits at gateways, but within a segment, it doesn’t work that well without some help.  Why?  Well, with tcp-based connection-oriented protocols, a handshake (consisting of a client syn packet, a server syn-ack packet, and a server ack packet) sets up the connection.  When you introduce the LTM, a problem arises: Client –> syn –> BIG-IP BIG-IP –> syn-ack –> Client...

Benefits of Desktop Virtualization

There is an abundance of mature desktop virtualization solutions that are outright free or at least reasonable.  From VMware’s Workstation (at cost after 30-day trial, but entirely worth it) to Oracle’s VirtualBox and Microsoft’s Virtual PC, you can get started in literally minutes.  Why would you want to? Trivial backups.  Tired of losing a drive and having to restore first the OS, then the applications, and finally your files?  Once everything is hosted on a virtual disk, keeping that backed up frequently means a physical disk failure costs you only the time to restore the hardware...