Exchange 2003 high CPU (mad.exe)

I noticed recently that both of my DCs and my Exchange 2003 server were running at higher CPU than normal. Only one of the DCs is a GC and it had recently fallen over due to a hardware failure, but had since been running for a few days without problems.

As the CPU usage was not excessive (20% on Exchange vs. typical usage of around 3-5%; 15% usage on the DCs compared to typical 1-3%) it had not impacted on performance, so I only noticed it from a perfmon trace I leave running against all servers. I logged onto a DC, ran task manager (taskmgr.exe) and found the task with highest CPU: lsass.exe. A quick scan through the event logs on the affected servers didn’t turn up anything significant.

I then ran filemon to see what files lsass was accessing and give me a quick insight into where the problem might lie. Almost all the accesses were relating to ntds.dit – the AD database. This microsofty’s blog post had some good advice on tracking down CPU issues, but I couldn’t really use the tip of unplugging the server from the network so Wireshark was a better option. I chose to run wireshark on the DC to check if the AD activity was generated on the DC itself or if a remote server was querying AD. As it turned out, Exchange was generating a lot of queries relating to other forests in the domain. Exchange is renowned for being very stroppy about having good access to a GC and the information from Wireshark made me suspect that Exchange had become upset after a weekend without access to a GC in our AD site.

I moved over to the Exchange 2003 server and checked the high CPU services on there. Top of the pops was mad.exe – the Exchange System Attendant. The excellent Microsoft Exchange Team blog (you had me at ehlo) had a useful article entitled The Cliff Notes on System Attendant (MAD.EXE). That confirmed my suspicions that Exchange was going a little bit haywire with AD queries so as a quick fix I restarted the system attendant service and its dependant services from the Windows services console (services.msc).

The high CPU persisted for a couple of minutes and then subsided. Another quick scan through the Exchange server’s event logs showed a splattering of ExchangeAL errors in the Application event log like this one:

Event Type: Error
Event Source: MSExchangeAL
Event Category: LDAP Operations 
Event ID: 8270
User:  N/A
Description:
LDAP returned the error [10] No Such Attribute when importing the transaction 
dn: <GUID=**********>
changetype: Modify
msExchPoliciesIncluded:delete:{**********},{26491CFC-9E50-4857-861B-0CB8DF22B5D7}
msExchPoliciesIncluded:add:{**********},{26491CFC-9E50-4857-861B-0CB8DF22B5D7}
msExchALObjectVersion:329
objectGUID:**********
-

… but they subsided after a couple of minutes too and the storm was over. Mad.exe was back down to 0.00% CPU and the DCs were behaving themselves. Job done.

 

SIMS.net bug #8476A75E256

Sometimes getting SIMS.net to run smoothly seems like an impossible task. It’s something like painting the Forth Bridge only when you get to the end, you not only have to start again, but also you realise they’ve replaced the damn bridge with 6 different bridges. Paint-resistant bridges. And it’s raining…  H2SO4.

Take for example the last few updates (Feb, Feb re-release and March). Like good little soldiers we upgraded one evening soon after February came out. Unfortunately it completely stomped all over our ability to add new teaching staff thanks to a bug which Capita themselves took quite a few weeks to really get a handle on. It also made three commonly-used menu options crash SIMS.net completely. We were told that a patch was being prepared but it would be unlikely to be finished until the March release, so Capita advised us to restore our SIMS server from backup tapes. Ahem…

I’m sure you can imagine the look of glee on the faces of our administrative staff as we told them we were giving them the opportunity to repeat all the work they’d done in SIMS/SIMS.net since we applied the February update several days earlier! Hmm. So that evening we restored from a backup taken before the update and for reasons unfathomable to me (possibly workstation-end) it somehow managed not to fix the problem. Luckily Capita then chose to release a patch to fix the problem. After waiting for everyone to get out of SIMS that night I found that it wasn’t created for our version of the database (we hadn’t been issued the Feb re-release). A call to Capita next morning lead to the re-release and patch being made available via SOLUS. Patch applied that evening. Didn’t fix anything. Oh well, there’s always the March update…

So a couple of days later the March update arrives. Much fanfare. That goes on quite smoothly (they’ve broken SOLUS in a couple of places but it’s nothing too tragic) and it’s all installed before the caretakers start jangling their keys at me. Unfortunately it’s not made a jot of difference to the problems that are now plaguing three of our most active SIMS users.

So now we are at the stage of requiring a site-specific fix, which means uploading our 1.2GB (zipped) database at ~50KB/s over what appears to be the only cobbled section of the information superhighway. Currently 15 failed upload attempts down and I’m starting to lose the will to live. Tomorrow morning I will probably give in and send it by DVD.

To give Capita credit where it’s due, their support people seem intelligent, responsive and genuinely keen to fix problems. It’s just a shame that they seem to have too many bug creators (programmers) for their team of bug spotters (testers).

Securing offline files

Let me start by saying, “Aaaaaargh!”. Now, on with the esoteric technorant!

I’ve spent nearly a day’s effort trying to get offline files to encrypt as they are supposed to in Windows XP. The advantage of doing this is that any data which has synchronised to a laptop from your network is protected when the laptop is offsite. Even removing the hard drive and connecting it up to another computer won’t yield access to the offline files. The only sure way of getting access to the files is to get the user’s password.

It seems that the only way to get the encryption of offline files working is to manually log on to each laptop as an administrator and turn the option on:

Windows Explorer > Tools > Folder Options > Offline Files tab > Encrypt offline files to secure data (tick)

This works quite nicely thank you and when connecting to \\testcomputer\c$\windows\CSC (the real location of your offline files) the files all show up with green filenames – cryptography applied! Unfortunately, doing that on each of 100 laptops sounds like as much fun as a Daniel O’Donnell concert and undoubtedly longer. I also have my doubts about whether the laptops would Ghost nicely afterwards.

Luckily there is a Group Policy setting at:

Computer Configuration > Admin Templates > Network > Offline Files > Encrypt the Offline Files Cache

(enabled|disabled|not configured)

On the downside, the setting doesn’t work. At all. In fact, all it does is greys-out the Encrypt offline files to secure data checkbox in the Windows XP GUI. I have verified that even with the above GPO setting in place and the testcomputer‘s Resultant Set of Policy (rsop.msc) report showing as much, the files on disk are not encrypted at all.

There are several reports on the web from people suffering the identical problem, but seemingly none with a satisfactory resolution. Suggested resolutions include:

Make sure the first user to log on after the policy is put in place is a member of the Administrators group

Tried it, made no difference.

Reset the offline files cache:

Windows Explorer > Tools > Folder Options > Offline Files tab > Ctrl+Shift+Click on Delete Files…
Tried it, the client-side cache was reset, but the encryption problem was unaffected.

Contact Microsoft Product Support Services for proof that the data is encrypted:

Ahem, no. I can prove that it isn’t with only a few minutes work and zero cost.

Make sure the partition is NTFS:

Yup!

And not compressed:

Nope!

Try applying the fix from MS KB810859 (The “Encrypt the Offline Files cache” Group Policy setting does not take effect when a user logs on to a Windows XP-based computer):

I don’t get the event specified in the event logs so it doesn’t seem to be relevant. I’m also using an admin account which should prevent the scenario described. On top of that you need to contact PSS for the fix, apply it to each of your workstations (not via WSUS) and then do some rather nasty looking ADSIedit manoeuvres! Nopety nope.

Quite a crap effort there Microsoft! Maybe if I just use Vista instead….

North West Education Technology Show 2006 at Reebok Stadium (Part III)

Seminar 3 – Planning for Online Personal Learning

By Robin Ball (BECTA)

SUMMARY: A strategic overview of how BECTA believes virtual learning environments should be introduced into schools. Particular focus on cultural changes within schools.

E-STRATEGY:

23,000 schools in England – one size won’t fit all
Initial provision – Online access to learning by 2007-8

LEARNING PLATFORM:

Outline:

• Primarily web-based
• Provision for file access
• Levels of sophistication: Basic repository, VLE or MLE
• Potential for integration into MIS although technology still not really available

Benefits:

• Customised learning
• Home learning (improving inclusion)
• 24/7 Access
• Parental involvement & pupil tracking
• Sharing aims & progress with pupils

How to make it happen:

• Skills – Assess requirements
• Involvement – Consult with staff, SLT, parents
• SLICT – Strategic Leadership in ICT, 2-day course for headteachers

Planning:

• Change management – 5 key elements: vision, skills, incentives, resources, action plan
• Accessibility
• Sustainability
• Data exchange
• Support, maintenance & training
• 5 point plan: product, installation, maintenance, support, training

BECTA Progress:

• Functional specification defined for Learning Platforms
• Procurement process in progress – expected completion Jan 2007

LINKS/FILES/CONTACTS:

http://www.ncsl.org.uk/slict (SLICT course)
http://www.becta.org.uk/publications (BECTA publications)
http://www.swgfl.org.uk/streaming/lp_robin_ball.asp (video of earlier presentation)
How to Get it All Wrong.htm (what to avoid in VLE implementations)
6 Learning Services 2006 NDI.ppt (Powerpoint from seminar)
robin.ball@becta.org.uk

North West Education Technology Show 2006 at Reebok Stadium (Part II)

Seminar 2 – Collaboration in an Online Environment

By Kevin Thompson (UltraLab / UltraVersity)

SUMMARY: A brief description of the UltraVersity project and a discussion of new collaborative technologies, focussing mainly on websites with a strong collaborative theme.

PROBLEMS:
Conflict between old and new ways of teaching & learning:

• “Solo” examinations vs. collaborative working
• Taught vs. self-taught
• Passive learning vs. Active learning
• Dissemination vs. Communication

What is required in the modern workplace?

ULTRAVERSITY:

• Degrees delivered entirely online
• Students all in full- or part-time employment
• Students geographically spread and don’t meet in person until graduation
• 140 Graduates this year

FOUR C’s OF SOCIAL TOOLS:

• Communication: email / instant messaging / voice over IP
• Coordination: shared calendaring / contacts
• Collaboration: files / wikis / blogs / writely.com
• Community: social networks / group decisions

COLLABORATIVE / COMMUNITY WEBSITES:

• Encyclopaedia: Wikipedia
• Video: YouTube, Google Video
• Art: Artpad.art.com
• Photographs: Flickr
• Music: Pandora, Blogmusik
• Bookmarks: Furl, Del.icio.us
• Documents: Writely (aka Google Docs&Spreadsheets), Writeboard
• Maps: Frappr

KEY POINTS:

• Learners can contribute to the learning process by communication with both teachers and other learners
• Online communities can work, but require some facilitation
• Wider participation does not mean watered-down teaching

LINKS/FILES/CONTACTS:

http://www.ultraversity.net
http://www.ultralab.net
Kevin Thompson Powerpoint NWETS 06 (Powerpoint from seminar)
ltscotland-sett2006-D1C.mp3 (Audio recording of earlier seminar)
kevin can be emailed at ultralab net

North West Education Technology Show 2006 at Reebok Stadium (Part I)

Some notes from the first seminar I attended at the NWETS on Wednesday 15th November 2006 

Seminar 1 – Harnessing Technology – A Strategy for Personalised Learning

By Norman Crawford (BECTA)

SUMMARY: A brief discussion of how personalised learning can be achieved through the correct use of technology, particularly by the use of virtual learning environments.

PROBLEMS:
• Only 1 in 6 schools using ICT effectively as of 2004 (source?)
• Often caused by the use of unsuitable technology
• Lack of 24/7 access hinders use

STRATEGY:
• Broadband infrastructure projects – largely completed
• Provision of content – don’t overlook
• “E-maturity” – skills and practices which make the most of the technology available – referenced Becta Matrix (self assessment for schools) & ICT Mark (Accreditation scheme)

DESIRABLE OUTCOMES:

• Closing achievement gaps
• More pupils following on to post 16
• Reducing levels of failure in adult life

(comparison drawn with Every Child Matters agenda)

E-CONFIDENCE”:

• School is: managed effectively, innovative
• Learner is: self-directed, capable of choosing the correct tool for the job

WEB 2.0”:

Some brief discussion of new trends in collaborative online communities which are popular with young people (myspace, piczo etc.)

LEARNING PLATFORMS:

Discussion of the terminology:

VLE – Virtual Learning Environment
MIS – Management Information System (e.g. SIMS)
MLE – Managed Learning Environment (i.e. VLE & MLE combined)

Discussion of the benefits:

• Collaboration between teachers
• 24/7 access

Discussion of potential issues:

• Transfer of data between schools (e.g. if pupil moves) may be problematic. Therefore systems should use open data standards. Borough/LA-wide systems may reduce the impact of this issue.

Additional benefits of LA-wide systems:

• Same login details across borough (parents/teachers etc.)
• Improved/easier collaboration between teachers at different schools
• Improved training provision

IMPLEMENTATION:

• Experience shows whole-school deployments best
• Planned strategically
• Teacher-lead

DEADLINES:

2008 – Personal learning space
2010 – Learning platform

LINKS/FILES/CONTACTS:

NW Ed Show Keynote Nov 2006.ppt
norman crawford can be emailed at becta org uk

Setting up secure WiFi in Server 2003 and Windows XP

These instructions are step-by-step, but fairly long and (as yet) without any screenshots. Hopefully they will be of use to someone! Good luck!

Requirements: 

Server: Windows Server 2003 Standard / Enterprise (I used standard) DC
Clients: Windows XP Pro SP2, wireless NIC supporting WPA
Access point: Most new wireless APs / routers will do. I used a Linksys WRT54GL with modified firmware from http://www.dd-wrt.com/ 

You will need to be a domain admin for your own domain, but you don’t need to be an enterprise admin. 

Summary: 

To get the secured wireless working we need to have a RADIUS server running which authenticates the wireless computers against Active Directory. In WS2003, RADIUS is provided by the Internet Authentication Service (IAS) which is a built-in windows component, but isn’t installed by default. 

To allow the laptops to verify that the server is what it claims to be, we need to set up certificates. In WS2003, this is done via Certificate Services which again is included with the OS, but not installed by default. 

Next, we need to tell the access point(s) where our RADIUS (IAS) server is and vice versa and then use Group Policy to tell the XP clients how to authenticate.

The finished wireless network will then be using WPA, PEAP (MS-CHAPv2) and AES.

Procedure: 

On the Domain Controller 

Setting up IAS: 

1)     Launch Add/Remove programs > Windows components > Networking Services > Details> Tick Internet Authentication Services > OK, NEXT
2)     Start > Programs > Administrative Tools > Internet Authentication Services
3)     Right click Internet Authentication Services (local) on left hand side > “Register server in Active Directory” > OK
4)     Right click Internet Authentication Services (local) > Properties > Ports – make a note of the ports used for Authentication and Accounting: you may need them for setting up your Access Point later
5)     Right click on Radius Clients > New Radius Client > Pick a friendly name and a static IP address you can use for the Access Point. Be sure not to choose something in your DHCP range. Select RADIUS Standard and enter a shared secret. Microsoft recommend 22 characters or more generated by a random password generator.
6)     Click on Remote Access Logging > Right click on Local file > As a minimum, select Accounting Requests and Authentication Requests and check the Log File tab settings.
 

Setting up Certificate Services:

7)     Launch Add/Remove programs > Windows components > Certificate Services > Details > Tick Certificate Services CA > YES > OK > NEXT
8)     In the Windows Component Wizard window:
a.      Choose “Standalone Root CA”. If you are an enterprise admin and know how to set up autoenrollment, you might want to choose “Enterprise Root CA”, but standalone should work in all cases. NEXT.
b.      Choose a “common name” such as StTriniansRootCA, increase the validity period from 5 years (I used 25), NEXT
c.      Click YES to stop the IIS service.
d.      Choose YES to installing ASP to allow web enrolment – we’ll be using that later
e.      FINISH
 

Creating and installing a server certificate: 

This process creates a certificate to prove the identity of your IAS server. By default the certificate only lasts 1 year before it expires. For instructions on increasing this value, visit http://support.microsoft.com/?id=254632
 

9)     Open Internet Explorer at http://YOURSERVER/certsrv
10)  Click “Request a certificate”
11)  Click  “advanced certificate request”
12)  Click “Create and submit a request to this CA.”
13)  The “Advanced Certificate Request” page must be filled in carefully, in particular the following fields:
Name – The fully qualified name of your server as the wireless clients see it, e.g. yourserver.yourdomain.int
Type of Certificate Needed – Choose “Server Authentication Certificate”
Create new key set – Select this option
CSP – Choose “Microsoft RSA/Schannel Cryptographic Provider”
Key Size – 1024 should be fine. Bigger numbers give better security, but increase the processing power required.
Mark Keys as exportable – Tick this
Store certificate in the local computer certificate store – Tick this
14)  Click Submit >
15)  The next screen tells you to come back later when your certificate has been approved, so go back to the Certification Authority snap-in, expand your Root CA > Pending Requests > Select the request > Right click > All tasks > Issue. It should move into the Issued Certificates container.
16)  Open Internet Explorer at http://YOURSERVER/certsrv (again)
17)  Click “View the status of a pending certificate request”
18)  Follow the link to install the certificate you just created.
 

Creating a Remote Access Policy: 

19)  Create a security group (e.g. WirelessComputers) in the Active Directory Users and Computers snap-in and add all your wireless laptops and PCs as members of the group.
20)  Start > Programs > Administrative Tools > Internet Authentication Services
21)  Right click on Remote Access Policies > New Remote Access Policy
22)  NEXT
23)  Make sure the “Use the wizard…” option is selected and type in a name, such as “Wireless Access to the St. Trinians network”. NEXT.
24)  Select “Wireless”, NEXT
25)  Select Group, click Add… and find your WirelessComputers security group. NEXT
26)  Select “Protected EAP (PEAP)” and click Configure…
27)  Pick the certificate with your IAS server’s fully qualified domain name e.g. yourserver.yourdomain.int
28)  “Enable fast reconnect” is optional, but most sources I have found suggest that you tick it.
29)  “Secured password (EAP-MSCHAP v2)” should be the only item in the list
30)  Click OK
31)  NEXT
32)  Finish
 

Pushing Wireless Networking policies out to workstations: 

Some steps required for this section vary depending on whether the Group Policy Management Console (GPMC.msc) has been installed on your server or not, so those steps are described in a general way. 

33)  Create a new Group Policy Object and link it to the OU containing your wireless computers
34)  Disable the user portion of the GPO (not necessary, but good practice for speeding up application of the policy)
35)  Edit the policy
36)  In the Group Policy Object Editor snap-in, navigate to Computer Configuration > Windows Settings > Security Settings > Wireless Network (IEEE 802.11) Policies
37)  Right-click Wireless Network (IEEE 802.11) Policies > Create Wireless Network Policy
38)  NEXT
39)  Type a name, e.g. “St. Trinians Secure Wireless Network”, NEXT
40)  Tick “Edit properties”, FINISH
41)  In the properties of the policy, select the General tab
42)  Set “Networks to access” to “Access point (infrastructure) networks only”
43)  Tick “Use windows to configure…”
44)  Untick “Automatically connect to non-preferred networks”
45)  Click the “Preferred networks” tab
46)  Click “Add…”
47)  Pick the SSID you will be using to identify the network, e.g. SchWlan1 This will need to match the SSID set up on your access point(s).
48)  Set “Network Authentication” to “WPA”
49)  Set “Data Encryption” to “AES”
50)  Click the IEEE 802.1x tab
51)  Set the EAP Type to “Protected EAP (PEAP)”
52)  Click Settings
53)  Tick “Validate server certificate”
54)  Tick “Connect to these servers” and type in the name of your IAS server
55)  Under “Trusted Root Certification Authorities”, find the Root CA you created earlier and tick it
56)  Tick “Do not prompt user to authorize new servers or trusted authorities”
57)  Select “Secured password (EAP-MSCHAP v2)”
58)  Tick “Enable Fast Reconnect”
59)  OK
60)  Untick “Authenticate as a guest…”
61)  Tick “Authenticate as a computer…”
62)  Computer Authentication: “Computer only” (This setting will prevent the computer being disconnected and reconnected while the user is logging in.)
63)  OK
64)  OK
65)  In the Group Policy Object Editor, move down to Public Key Policies and right click on Trusted Root Certification Authorities
66)  Import…
67)  NEXT
68)  Type \\YourDCName\CertConfig\ and click Browse…
69)  Pick the Root CA certificate, OPEN
70)  NEXT
71)  NEXT
72)  FINISH
73)  Close the Group Policy Object Editor
74)  To apply the policies, connect the wireless computers via a wired connection, log in, run “gpupdate /force” then reboot.
Setting up the wireless access point: 

Obviously this depends very much on the model of the access point, so these instructions are very generic. 

75)  Look for an option for setting up WPA with Radius. On the superb DD-WRT firmware this is under Wireless > Wireless Security.
76)  If there is an option to choose between AES and TKIP, choose AES
77)  For the RADIUS server address, enter the IP address of your domain controller running IAS
78)  For the RADIUS port, enter the port number you made a note of earlier on. By default this will probably by 1812.
79)  Enter the WPA shared key: this should match exactly with the “shared secret” you used when setting up IAS.
80)  Set up the SSID to match what you put in your Wireless Networking policies sent to the clients, e.g. SchWlan1. If you want disable broadcasting of the SSID it will make your network less visible as a target to casual snoopers, but it might make it more difficult to troubleshoot problems with your setup.

Making mailto: links work in OWA

I recently had one of those moments which I guess all techies have from time to time, where a once small irritation reaches the level where you have to completely obliterate it from existence. In this case, it was accidentally clicking on a mailto: link on a web page. For a number of reasons, here in school everyone uses Outlook Web Access, me included, but the mailto: link always starts up Outlook 2003. I then spend the next minute waiting for it to slowly get its act together so I can shut it down again and get on with my day. I decided to find a way to make mailto: links create a new message in Outlook Web Access instead and after a couple of hours’ work here it is:

You will need:

  • A web server which runs ASP pages
  • Outlook Web Access for Exchange 2003 (other versions not tested but may work)
  • Internet Explorer installed on your clients (doesn’t need to be the default browser)

First, create an empty text document called exchredir.asp and put the exchredir.asp code listing into it. (I’ve had to store the code listing in a Google Notebook, because WordPress is a complete tart about quoting code) Make sure you edit the text in red to reflect your OWA server’s name; text in green can be customised to suit your setup, but isn’t critical.
Drop exchredir.asp into a new folder on your ASP server where people can get at it, but make sure that you turn off anonymous access to the folder so that the script can pick up their username. To do that go into the IIS management console, find the directory containing exchredir.asp in the treeview on the left, properties > directory security tab > anonymous access and authentication control > edit > untick anonymous access.
Finally, your computer needs to know that mailto: links are opened by our script so we need to register the “URL:MailTo Protocol” filetype in Windows Explorer (Tools > Folder Options > File types).

Folder Options dialog

Use the “Advanced” button to edit the action for “open” so that it reads, including quotes:

c:\program files\internet explorer\iexplore.exe” http://server/path/exchredir.asp?mailto=%1

which makes the setting for all users of that computer.

Editing the MailTo Protocol settings

Edit Open Action

For a large number of users you may need to manipulate the registry keys at:

HKEY_CURRENT_USER\SOFTWARE\Classes\mailto\shell\open\command
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\mailto\shell\open\command

more info here: How to implement a per-user default mail client in Windows XP?

Now try testing a mailto link on a web page, such as the one at the end of the first paragraph of: http://www.bbc.co.uk/blogs/ouch/ . It should pop up a new email message in OWA with the To: field filled in for you.

Limitations:

At the moment I don’t know of a way of passing the subject into a new email message in OWA and it may not be possible at all, so I just drop the subject line – you’ll have to type it in yourself.

WinDirStat – Find out what’s taking up all your disk space!

This may not be new to some, but WinDirStat is an excellent free tool for visualizing the space taken up by files on your hard disks or network drives and cleaning out clutter. I first used it a few months ago, but when one of my servers recently got worryingly low on space during a service pack install WinDirStat came to the rescue!

WinDirStat main interface

As you can see from the screenshot above, the program doesn’t just give you a simple bar or pie chart of your top-level directories, it also produces a view known as a Treemap. The Treemap displays a coloured rectangle for each file on your drive – larger files have larger rectangles. The rectangles are also clustered together into folders: if you look carefully at the screenshot above, there is a white rectangle surrounding about half of the treemap’s area. All files within that rectangle are inside the same parent folder (in this case “c:\program files”) You can hover your mouse over any part of the treemap and the status bar will show you which file it represents.

But why the wacky colours? The colours in the treemap represent different filetypes (determined by their filename extension) so that you can see at a glance which type of file is occupying the most disk space. Ingenious!

So how did this help my ailing server? I ran WinDirStat from a share on our network whilst logged on to the server and started a scan of the c:\ drive. A few seconds later the treemap showed up and two large files were standing out:

c:\pagefile.sys (the windows swapfile) – 1.5GB

c:\Program Files\Websense\bin\xid_trace.txt (a mystery file!) – 1GB

A bit of googling told me that xid_trace was just a logfile generated by our Web filtering software (Websense) on the servers which perform authentication (known as DC Agents). Every time a user had requested a page from the Internet, a line had been logged in xid_trace.txt to record the event (as well as our standard database logs). Ouch. I zapped the file from within WinDirStat and added it to my list of logfiles to prune periodically. If only applying service packs was so quick and painless!

Fantastic geometry/algebra software for nowt! – GeoGebra

Just a quick post this one, but hopefully useful to your Maths departments.

Take a look at these screenshots of GeoGebra. Now visit the GeoGebra WebStart page and click on the button (proper Java required). Amazingly this amazing piece of dynamic geometry software is not only free, but also runs without an installer, even under a standard user account. It will (optionally) create shortcuts and file associations for the pupil too. I’ve seen Java WebStart before and thought it was pretty nifty, but to be honest I’ve never really seen any truly worthwhile uses of it until now.

But that’s not all! You can even create web pages with your saved GeoGebra files preloaded into them (as in this GeoGebra example) – fully interactive worksheets with very little effort. There are more sites full of examples around the web, including these:

SLU.edu GeoGebra Applets (hard maths!)

Henrico County GeoGebra Applets (easy maths!)

For a school that has struggled through with Omnigraph for years and (I gather) tried some of the more expensive commercial oferings without luck, this is a real revelation. The large buttons make me think this could be a good tool for use on interactive whiteboards too.

Caveats & fixes

Unfortunately at the time of writing the author’s security certificate has expired. Depending on your settings this may cause some problems with the initial setup. Under Windows with Internet Explorer, try clicking OK to problems with the certificate. If you aren’t even given that option, put www.geogebra.at into your trusted sites list in IE, clear your cache and restart IE. As a network admin, you can add it to trusted sites for all or part of your domain via a GPO.