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Network Troubleshooting I was helping someone troubleshoot a network problem last week. As it turned out, the problem was very physical: a light fixture had fallen down an loosened some connection to a switch. Both the existence and the location of that switch in relation to the rest of the network had vanished from institutional memory so much of the testing we were doing didn't make sense and was hard to interpret. In fact, it was so puzzling that I drove on-site with more sophisticated testing equipment, only to find that someone had noticed the fallen fixture before I arrived. Problem identified and solved, but it did prompt me to look for a general "Network Troubleshooting" page here and I was a bit surprised not to find one.


Title Date Comments
Joe's computer turns 3   2011 07 
- I'm really excited because soon I may get to run Linux! I have been hoping for that for years and had just about given up on the idea when they tried to install Windows 7 on my drive. -
Per-user screen sharing in Lion   2011 06  2011/10/03 TonyLawrence
- There are possibilities for extending the life of older Macs and really exciting possibilities with iPad VNC. -
The Lion roars - did I just yawn?   2011 06  2011/06/10 Sledge
- I thought Lion was really exciting, but that has faded away quickly. The reality is that Lion is not for me. -
Helping my sister-in-law with Gmail   2011 06  2011/06/02 TonyLawrence
- I'd rather send pictures or a move than take control of their computer. They can refer back to what I sent over and over again. -
Tuning Mac OS X for FIOS   2011 05 
- Tuning for broadband isn't as easy as you might think. Your usage matters and it matters a lot. -
TinyTERM ITX for Mac   2011 05 
- TinyTERM ITX for Mac OS X is somewhat disappointing - the emulation is fine, but it is a poor Mac app. -
Sophos free anti-virus for Mac   2011 05  2011/05/23 TonyLawrence
- Although the main threat to Macs is trojans and malware, not viruses, the common man doesn't distinguish these - they are all the same to most folks. -
Slow Finder when browsing SMB Network Shares in Snow Leopard   2011 04  2012/08/08 anonymous
- Mac OS X finder in Snow Leopard, when bound to Active Directory can be painfully slow at just listing files on a SMB share. -
Mysterious Duplicate IP addresses   2011 04  2011/04/20 TonyLawrence
- Proxyarp on smart switch causes sudden appearance of duplicate ip addresses: All machines on our 192.168.206.x subnet (mostly Mac's, with Windows servers) got the IP conflict message when they started up in the morning. We do have a linux dhcp server running on that subnet, but it only hands out 2 IP addresses for barcode guns, and those are given the IP based on their MAC address, so each barcode gun always gets the same IP and can move to other buildings without reconfiguring them, as they run in dhcp mode. -
Finding Yesterday's Date   2011 04  2014/02/05 TonyLawrence
- How to find yesterday's date on Linux, Mac and any other Unix. -
Murder and mayhem - killing users processes   2011 04  2011/10/28 BigDumbDinosaur
- how to kill all of a specific user's user processes without "killall" - or select a subset to kill -
Slightly Scrambled - unsorting a file   2011 04  2011/04/05 TonyLawrence
- Here is a typical way to approach the problem. It uses Perl's associative arrays and (somewhat ironically) uses -
 
 
 
 
Snarling Panda site cleanup   2011 03 
- The problem is "low value content". That's tough to define absolutely, but some pages here definitely fall into that category -
Smarter HTML Link Extractor   2011 03  2011/07/20 TonyLawrence
- Checking links is not really hard; you can actually do it with just a few lines of Perl. -
Environment variables - maximum size of a variable?   2011 03 
- An 18 MB or larger variable is much more than any shell script is likely to need, but it shows that you need not fear assigning large chunks of data -
Cisco VPN's with VPN Tracker 6   2011 01 
- Mac users get ignored by Cisco and many other VPN providers. VPN Tracker 6 gives you access to those VPN's. -
Thinking iPad for Xmas?   2010 10  2011/11/30 TonyLawrence
- Are you thinking iPad for Xmas? I think iPad is the ideal second computer. However, other companies are offering similar devices. -
How do I fix files showing up as 0k on a SMB mount in Snow Leopard?   2010 09  2013/10/08 BruceGarlock
- We have been battling a strange Snow Leopard font issue (who hasn't) for a while now, and this one seemed to work on some SL machines, and not others. As it turned out, I had made some changes as to the way SMB connections happen on my machine, so I couldn't reproduce this issue. I had even made this change on a couple of our Art department managers machines, so we couldn't get it to mess up on their machines either. The problem presents itself like this: -
Converting File Encodings   2010 09  2010/11/03 anonymous
- Converting File encodings on MacOSX UTF-16 to 8 bit ascii and an odd complaint from cron caused by DOS line endings. -
Free iPad book   2010 06 
- Free e-books are often barely worth the time and trouble it takes to download them. They are often just thinly veiled advertising vehicles promoting some other product -
iPad Keynote with VGA projector or display   2010 05  2010/07/27 TonyLawrence
- How to make an external monitor work with Keynote and your iPad - it's too balky right now! -
iPad app file extensions   2010 05  2011/08/05 TonyLawrence
- Finding iPad uti file extensions can be confusing. There is an app that lets you look up the apps that belong to particular extensions, but you don't need to buy anything to find the extensions that an app you own recognizes. -
iPad 3G   2010 05  2010/10/07 TonyLawrence
- When to cancel ipad 3g - leaving it on constantly seems like a waste of money to me. -
Traveling with the iPad   2010 05  2010/05/25 TonyLawrence
- Traveling with the iPad is not the annoyance that some insist. I have no issues worth griping about. -
iPad passwords   2010 05  2010/05/05 MarcFarnumRendino
- The iPad keyboard and its affect on passwords - some good passwords are very hard to type. -
iBooks vs. Kindle   2010 05 
- Differences between Kindle and iBooks - I like the iBooks versions better but Kindle does have its charms. -
Improving the iPad keyboard   2010 05  2011/04/06 TonyLawrence
- Apple iPad needs a fully programmable custom keyboard option. Why has Apple left this out? -
It's the overall experience that matters   2010 05 
- iPad apps can be less than stellar - yes, there is an app for that, but there's a good chance it's a crappy app. -
My iPad Senior Moments   2010 05 
- Where is that iTunes icon now? I do have my senior moments, but this weekend was unusually bad. -
It's only going to get better   2010 05  2010/05/09 TonyLawrence
- Perfection is in sight - masybe it's not quite the dawning of a new age, but iPads are something very close to that. -
If I could talk to Steve Jobs   2010 05 
- Three things the ipad really, really needs. These are very obvious omissions that should be fixed ASAP. -
Waiting for the..   2010 05  2010/05/07 TonyLawrence
- The iPad vs hp slate and android: I am all for Android devices competing with Apple. Competition is good, and we all will benefit. -
On the fourth day of iPad..   2010 05  2010/05/05 MarcFarnumRendino
- Getting more comfortable with the ipad - some attitude adjustment is required, but I can do most of my work there. -
First day with iPad   2010 05  2010/05/04 TonyLawrence
- I can do 90 percent of my daily work with my iPad. I imagine many will be able to do everything. -
Finding Leaks in Xcode   2010 04  2010/07/02 abes
- Finding memory leaks with Xcode turns out to be much harder than I thought it would be. -
Basics of the iPhone/iPad SDK   2010 04  2010/04/07 TonyLawrence
- Getting started with the iPhone SDK (Software Development Kit) -
iPad Application Development For Dummies   2010 04 
- Very good explanation of iPhone/iPad SDK development nuts and bolts -
iPads being delivered today   2010 04  2012/06/11 TonyLawrence
- Fedex drivers were greeted by the strange sight of geeks rushing out to meet their trucks or already at the curb, bouncing up and down, giddy with excitement. Many a geek inflicted neck strain upon themselves from stretching to see if the Fedex truck was coming. Others were obviously distressed with indecision: should they stand outside awaiting the delivery or go back in and reload the tracking page? Sometimes this problem was solved by keeping children home from school: little geeks-to-be were seen shouting out windows: 'No change, Dad, no change'. -
Xcode 3 Unleashed   2010 04 
- Knowing Xcode is definitely part of knowing the SDK: Yeah, well that worked - sort of. You can just wander in and use Xcode without really knowing all that much about it. However, you'll probably miss things that can really add to your productivity. -
Beginning iPhone 3 Development   2010 04 
- I liked this because it dove right in to things I need to know about the iPhone SDK -
The iPhone Developers Cookbook   2010 04 
- This book helped clear some confusion about the iPhone SDK: This title was mentioned frequently when I was looking for good books to get me started with iPhone/iPad programming. There were a few negative comments - one particular jibe from a college professor was especially cutting. He's probably one who gets all snitty if a students indentation style doesn't match his own, so I ignored that. -
Adventures in Xcode and the iPhone SDK II   2010 04  2010/04/24 TonyLawrence
- There is a lot of pain in getting started with IOS development. I've made some progress, but I'm not sure how far I can go. -
Adventures in Xcode and the iPhone SDK   2010 04  2010/04/20 TonyLawrence
- I must have been missing a big chunk of something, because a reinstall took away an extra GB of disk. -
Thinking about that iPad   2010 04  2010/04/07 TonyLawrence
- Do I want to buy an iPad? Can I possibly NOT buy an iPad? It seems that I really cannot avoid this. -
Network Troubleshooting   2010 03  2010/03/16 AndrewSmallshaw
- As it turned out, the problem was very physical: a light fixture had fallen down and loosened some connections to a long forgotten ethernet switch. -
What does a leading colon (:) mean in a script?   2010 03 
- Bash and sh both use colons (":") in more than one context. You'll see it used as a separator ($PATH, for example), as a modifier (${n:="foo"}) and as a null operator ("while :"). -
Cheap laptop, Netbook or .. iPad?   2010 03  2010/04/01 TonyLawrence
- Best Buy to sell ipads, which is a very smart move for Apple. Not everyone has an Apple store near them. -
MacScan   2010 03  2010/03/26 TonyLawrence
- There's a bounty on your Mac. It isn't much money, but it's what the market pays.. -
Basic TrueCrypt Usage   2010 01  2010/01/12 TonyLawrence
- People have said that they installed TrueCrypt, but have no idea what to do next. OK, maybe the interface isn't all that user friendly. -
Lan sniffing with a DualComm port mirroring switch and Windump   2010 01  2010/01/23 TonyLawrence
- Using Dualcomm Port Mirroring switch and Windump to trace network problems and detect virus activity. -
 
 
 
 
Why the iPad IS important   2010 01  2010/01/30 TonyLawrence
- Why the ipad's defects don't matter. There will people who insist they don't need it, don't want it. They'll be lying to themselves. -
Mac OS X Scrabble Word Trainer with Growl   2010 01  2010/04/11 TonyLawrence
- A little scripting lets Growl toss up any sort of message ypu'd like, as often as you like. -
Unix and Linux startup scripts, Part 1   2009 12 
- In the beginning, there was "init". If you had a Unix system, you had "init" and it was almost certainly process id 1. -
Unix and Linux startup scripts, Part 2   2009 12  2009/12/11 TonyLawrence
- The rc.d system is used on NetBSD, FreeBSD and DragonFly (andpossibly a few other systems) to launch daemon processes when the system goes multiuser. -
Unix and Linux startup scripts, Part 3   2009 12 
- We have looked at both System V and BSD methods; until fairly recently that would hav e been the end of the discussion. -
Why Microsoft should fear Chrome OS, Linux and Apple   2009 12  2011/04/20 TonyLawrence
- The big question is how Microsoft will fare if Chrome OS and Apple's rumored iTablet (whatever they finally call it) become popular. -
Using color in shell scripts (Linux, Mac OS X)   2009 11  2010/01/03 BigDumbDInosaur
- Color is tricky. Displays can be bad at it, people can be color blind... using colors can make text hard to read - I don't like using color in scripts. -
Sort -u vs. uniq   2009 11 
- Don't tie yourself in pipeline knots with either of them; learn to use each of them appropriately and your scripts will be easier. -
Awk vs. Perl   2009 11  2012/08/15 TonyLawrence
- Sure, I used to use awk. When I used it, you weren't likely to find Perl onmost Unix systems, so for a lot of text mangling, awk was at least easier than writing in C or anything else. It did the job, and you'd get used to its quirks. -


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