Digital-Traffic.net

A while back I did some experimentation with IPv6 on my Cisco 2611xm. I was using a tunnel provided by Hurricane Electric, which worked well, but I had no firewall and that made me a bit nervous. A little while after I got things set up, I procured a Cisco ASA5505 with a 50 client license via eBay. My hope was that I could use the ASA for the firewall and the router to terminate the tunnel. As it turns out, this would have required a second IP address, because the ASA is not able to pass Protocol 41 traffic.

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Technology cisco, IPv6, networking

In my last post I described my experience with upgrading from VirtualCenter 2.5 to vCenter4. Here I’ll be describing the process of upgrading the host machines via a couple of different methods as well as my process for getting the VMs upgraded to the latest verision of VMware’s virtual hardware.

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Technology migration, virtual machines, virtualization, vmware

Last week I started our migration from VMWare’s VI3 to vSphere. There are many improvements to the load balancing capabilities as well as the management capabilities. The storage engine has been greatly improved as well. Storage vMotion is available in the GUI without a plugin and thin provisioning is finally available, which is a huge boon and reason enough to make the move on its own. Most of this process can be completed with no downtime for the virtual machines.

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Technology migration, upgrade, vcenter, virtualization, vmware, vsphere

I was given a project, recently, that involved creating a spreadsheet to list storage capacities and free space. One thing I wasn’t sure of, was how to format the values.

A bit of searching on the internet for formatting KB MB, etc. came up with a post by Ajay on http://www.eggheadcafe.com which suggested pasting the following code into the current worksheet’s private module:

Private Sub Worksh5eet_Change(ByVal Target As Range)
    If Not Intersect(Target, Range("C:C")) Is Nothing Then
        If Target.Value < 1000 Then
            Target.NumberFormat = "0 \B"
        ElseIf Target.Value < 999500 Then
            Target.NumberFormat = "0.000, \K\B"
        ElseIf Target.Value < 999500000 Then
            Target.NumberFormat = "0.000,, \M\B"
        ElseIf Target.Value < 999500000000# Then
            Target.NumberFormat = "0.000,,, \G\B"
        Else
            Target.NumberFormat = "0.000,,,, \T\B"
        End If
    End If
End Sub

I had some trouble with the macro and eventually abandoned it, but it did give me some ideas. The actual formats were good and I ended up using them later. The criteria for setting the formatting was spot on as well. After thinking about it for a while, I decided to look into Excel’s conditional formatting feature. There are premade rules for changing the cell color, etc., but it turns out that it’s capable of quite a bit more.

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Technology conditional formatting, excel, formatting, microsoft, spreadsheet

If you’re a systems administrator and run Vista, you might have run into some trouble with the server 2003 administration tools package (adminpack). Well, there’s good news for you. Remote administration is now built into the Vista operating system.

1. Firstly, you should be running service pack 1. I believe the tools are available for the original release of Vista, but I haven’t delved into it.
2. You’ll need to download the updated RSAT pack from Microsoft:

   Microsoft Remote Server Administration Tools for Windows Vista…

   • …for x64-based Systems
   • …for x86-based Systems
3. Go to the control panel and open “Programs and Features”.
4. Click on “Turn Windows features on or off.
5. Find and enable “Remote Server Administration Tools”.

Once you hit OK, your system will spend about 5-10 minutes configuring itself for remote administration and the “Administrative Tools” menu should be populated.

Technology administrative tools, remote, vista, Windows, Windows Server

I recently ran into an issue where a WSH script was calling an external executable and returning an exit code of 0 even though there had been an error running the external executable. The problem is that I was relying on oExec.StdOut.ReadAll() to block the script until the command had finished processing. The ReadAll() method functions synchronously, so if the executable had been writing to StdOut, I would have been right. Unfortunately, I was neglecting the StdErr stream. So, not only did I miss the errors that the executable threw, the script didn’t block on the executable’s output, so I returned the exit code before the executable had actually finished running. The lesson here is to always think about StdErr no matter what you’re trying to accomplish.

Technology bugs, development, scripting

I cut my system administration teeth on UNIX-based systems (OS X Server and Linux) and I quickly got used to being able to do a multitude of things very easily and efficiently from the command line. Windows, the main platform I support now, is missing a lot of these features. Every once in a while, after working on a Linux system, I’ll drop into a Windows command line and type something like tail -f foo.log just to get smacked with an error because the system has no idea what I’m asking of it.

Fortunately, the good people working on the GnuWin32 project have decided that Windows admins deserve a robust command line as well. GnuWin32 is a set of Windows-native executables that duplicate a large amount of the functionality found on a UNIX or Linux system. A lot of these little programs can make a Windows administrator’s life much easier. grep, tail, diff… all available without installing Cygwin.

The packages are distributed in a number of ways. Binaries are packaged in small collections. There’s are packages for the core utilities, diff utilities and separate packages for some of the other utilities like grep. There’s also a setup utility that functions as a package manager to help you keep all of the utilities up to date. Overall, this is a great project that’s definitely worth a look for anyone that hangs out in the CLI much.

Technology cli, Gnu, utilities, Windows

There have been a lot of articles floating around the net, lately, that mention how quickly we’re running out of IPv4 addresses. Seeing all of this got my interests in IPv6 rekindled. I’d been meaning to get it up and running on my network since I got my Cisco router, but it wasn’t until lately that I was really able to find enough information on the subject to know where to begin. I don’t have anywhere near enough knowledge to write up a tutorial, but I find it helpful and interesting to hear about other peoples’ experience with new technology. I hope it’s helpful for you to see how things went for me.

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Technology cisco, ip, IPv6, networking, routing

Everyone hates spam, and one of the main ways that people are fighting it is through the use of SpamAssassin. I’ve been using it for a while now and have Sieve detecting spam headers and moving them to my Junk folder.

The Problem

Dealing with spam that went unrecognized has been more of a manual process. Every once in a while, I’d have to segregate all of my useful mail from the spam and run “sa-learn” on the leftovers. This isn’t horrible, because I tend to shell into my server fairly frequently, but I really prefer to have menial tasks like this automated.

A solution

First of all, I created a folder in my mailbox called “Unrecognized Spam”. The name isn’t important, really. It just needs to be a place to file away all of those messages that SpamAssassin didn’t catch on the way in.
Once that was done, I wrote a very simple little script, which I dropped in /etc/cron.daily/:

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Technology linux, Maildir, scripting, spam, SpamAssassin

So, now that Hardy Heron is out, I’ve gone ahead and upgraded my server. It took a little while, but overall it went quite smoothly. Having the ability to go back and forth between the old server image and the new server image made it a much easier experience. Big thanks to Linode and virtualization.

Changes

One large change I made to my configuration is using Dovecot’s sasl authentication for Postfix rather than Cyrus. Dovecot really seems to be making headway in the mail server market. I strongly reccomend it to anyone looking for a decent IMAP server.

I’ve also upgraded to WordPress 2.5 and a later version of Roundcube for webmail. Unfortunately, Ubuntu seems to be holding Roundcube back a bit in their package repository. I’m not sure what the holdup is, but they’re at least one version behind at the time I’m writing this. For that matter, WordPress is a couple of releases behind as well. I guess that happens with an LTS release.

Todo

I’m still having a bit of trouble getting WordPress’ permalinks working correctly, so you’ll probably notice that some of the links aren’t working properly on the blog. I remember having this problem in the past, but, for the life of me, I can’t remember what I did to solve it.

Update: Got the permalink issue taken care of. Apache must be told, with the “AllowOverride” parameter, to allow .htaccess files. If this isn’t done, they will be ignored.

Technology Dovecot, Ubuntu, upgrade, Wordpress