Greg Smith

Goodbye OPSM - Hello Zenni Optical for Prescription Glasses

noreply@blogger.com (Gregory Smith) — Wed, 01 Jun 2011 11:25:00 +0000

I don't think I've ever been very satisfied with prescription glasses purchased from OPSM or the advice they've given me. I haven't tried the other stores - but I imagine they are similar. It's all marketing hype and the sad reality is expensive products with no real technical advantage over glasses offered by online stores.

My most recent OPSM purchase was a pair of occupational glasses (for computer use). Cost $159 for the frame, and $289 for the lenses (Invisibles Ultra - Plastic 1.49 progressives smudge resistant and anti-reflection coatings). The frame they suggested for me is huge and heavy. The lenses are thick and are already showing scratches despite care in handling and cleaning. Other OPSM glasses have cost $500 or more and I haven't been impressed. Typically it's taken 14 to 21 days to get the glasses once ordered.

In frustration I thought I'd buy a couple of cheap pair of glasses on the web to try different styles and configurations (bi-focal, progressive, occupational, etc.). I bought a pair of bifocal glasses from www.ozglasses.com for $70. They arrived in a week and were great. Then I bought a pair of progressives with bendable frame from www.zennioptical.com for $47. They were also good and arrived by courier to my home within 14 days of the order being placed on the web. Now I've just received a pair of featherweight no-rim glasses with lightweight progressive photochromatic lenses for less than $80.

Now progressive lenses are "evil" (distorted on the sides and very poor for intermediate distances). So I tend to use the bi-focals for reading and computer work (at my desk) and the progressives everywhere else. The point is that the OPSM progressives are no better or any higher quality that those from Zenni Optical. For the same price as one pair of OPSM glasses, I can experiment with half a dozen Zenni glasses to get the frame and lense combination that suits me the best. All with home delivery. I'm a satisfied customer.

So ignore the best efforts of the scare-mongering shop owners. Do your homework. There is plenty of information online about lenses, frames, online retailers, etc. Be happy to buy a few pairs on line to get the best results. It's still a hell of a lot cheaper and maybe you end up with a few spare pairs.

Extract thy Digit Tom Tom Navigator People!

noreply@blogger.com (Gregory Smith) — Thu, 30 Dec 2010 06:23:00 +0000

I purchased 2 TomTom Via 160 navigation units for Christmas presents for my wife and daughter. The specs looked pretty good and I was certainly impressed with the TomTom One and OneXL that my other daughter and son had.

What I enjoyed about the previous TomTom units was the "HOME" application that allowed downloading of new voices, maps, car icons, etc. Easy to use and very effective.

The new range of TomTom units don't appear to use "HOME". They appear to use a web based system called "MyTomTom". But the stupid thing is that this software IS NOT FINISHED. In other words, TomTom have happily released new models (just in time for Christmas) with INCOMPLETE functionality - and only with a promise akin to "we'll get around to it later".

The following is a summarised extract from the TomTom site under the guise of "Important information about devices connecting to myTomTom".

(From TomTom support site - summarised)
"We are currently introducing MyTomTom for the latest generation of TomTom devices. MyTomTom helps you manage the contents and services of your navigation device.

Some features are not yet available but will be in the near future.

* Latest Map Guarantee - Currently this functionality is not available for your device.
* Backing up - Currently this functionality is not available for your device.
* Adding POIs - Currently this functionality is not available for your device.
* Map updates - To ensure you always drive with the latest map, we offer our Map Update Service. Visit tomtom.com/mapupdate to find out if you are still up-to-date.
* New maps - Maps other than the one available on your device cannot be purchased at this point in time.
* Downloading voices - Currently this functionality is not available for your device.
* Activating promotions (service cards, etc) - Currently this functionality is not available for your device.
* Map Share™ - Currently this functionality is not available for your device.
* Sharing favourites - Currently this functionality is not available for your device."

Come on TomTom - pull your finger out and deliver on your promises!!

UPDATE : 12 January 2011

When I composed the above post, I emailed TomTom with a copy of it's contents. Today I got a phone call from a young man from TomTom apologising for the delay in the release of the fully functional MyTomTom software. He could not indicate a time for full deployment, but assured me that the 4 free map update promotion was still valid and I could expect to have my first update within a few weeks.

TomTom : Thanks for the call. Glad to see you taking customer service seriously and I look forward to the new software releases.

Some Xmas Pressies I got this year

noreply@blogger.com (Gregory Smith) — Tue, 28 Dec 2010 08:58:00 +0000

Some of the bestest Xmas pressies I got. A pedomoter (to keep me fit - 10,000 steps per day), a Jesus on a Spring dashboard icon (Google "Church of Jesus on a Spring"), and a T-Shirt that reads "You read my shirt - thats enough social interaction for one day". All good.

SPOT GPS Messenger

noreply@blogger.com (Gregory Smith) — Tue, 07 Sep 2010 09:22:00 +0000

I do a bit of bushwalking - a lot in areas not well covered by mobile phone. My wife gets worried when I'm away and often I have to climb hills to get some sort of mobile phone message to her to say I'm ok.

So for my birthday she bought me a SPOT GPS Messenger. This little device is like a personal EPIRB (Emergency Position Indicating Radio Beacon) but with the added extra that it can send pre-formatted email and mobile phone SMS recipients. So I can send my wife a "Checking In / I'm OK" message a few times a day. The email and SMS messages also send the GPS co-ordinates and a link to Google maps. If I get into trouble (like being stuck), I can send a "I need Help - come and get me" message. If I'm in a life threatening situation or seriously injured, I can send a "911" emergency message that goes to the US rescue center, who then relay the message to Australian rescue centres.

Relying on private satellite communication links (Globalstar) the service is subscription based. But for $115USD per annum you get unlimited email messages and 200 SMS messages. You can have up to 10 email and/or SMS recipients per message type - so I can not only keep my wife informed, but also my kids. The system also lets you set up a web page showing the last 30 logged locations. So in my mind the pricing isn't too bad.

There are certainly some pros and cons compared to conventional EPIRBs.

Pros of SPOT GPS Messenger

Cheaper to buy (around $300 vs $500-$800 for a personal EPIRB).
Can send non-emergency and or low priority help messages to friends and family - Check In/OK and pre-formatted custom messages (EPIRBs just send emergency messages).
Non emergency messages go to your friends and family (email and SMS), whereas EPIRBs send messages through an emergency response centre.
Sends "911" emergency messages through the emergency response centre (just like EPIRBs do but using a different satellite communications channel).
Can be used for tracking your trip (additional subscription).
Generally lighter than EPIRB units.
Replaceable batteries.

Cons of SPOT GPS Messenger

Relies on a commercial communications network (Globalstar) and private service provider to get messages through - maybe less reliable?
Emergency response in Australia relies upon a Memorandum of Understanding between the service provider (SPOT), the US rescue services (who will take the call initially), and the Australian rescue services (who get handed the call to act on it). You can download the unsigned MOU from here.
No homing beacon function - relies on GPS co-ordinates contained in the message to get the rescue people to you. If you move (for example to avoid flood waters), you would have to send another message with an updated position.
Annual subscription needed - $115 USD per annum.
Battery life is limited - EPIRB batteries generally last 5 years, SPOT uses replaceable lithium AAA batteries that last about a year (quite a bit less - some 7 days - if the unit is set for tracking mode that send a message every 10 minutes). Having said that, if you only turn on SPOT when you want to send the batteries should last some years. On a fresh set of batteries, SPOT should send continuous emergency messages (every 5 minutes) for a number of days.
Not 100% global coverage - most land areas but marine areas not covered well.

Just a note on the first bullet point above - Globalstar has been having all sorts of problems with it's satellite telephone service. Apparently the problem is failing satellite transmitters. Apparently this does NOT effect the "simple message service" used by SPOT.

Anyway, if you want to check out my location have a look at http://www.smithonline.id.au/?Greg:My_SPOT_Page. Yes, the map is "live".

You can get more info at www.findmespot.com and Google "SPOT GPS Messenger" to get some local retailers.

Cassette Kids in Perth

noreply@blogger.com (Gregory Smith) — Sun, 27 Jun 2010 03:20:00 +0000

Went to Amplifier to see the Cassette Kids in action in Perth. Great super dynamic show as always. Supported by KO88 from NZ.

Avatar the movie - Great Effects - Ho Hum story

noreply@blogger.com (Gregory Smith) — Thu, 28 Jan 2010 09:59:00 +0000

Just seen Avatar - 3D version. Great effects and despite it's length (161 minutes) a reasonably paced and engaging movie. It's a pity Hollywood can't seem to back/find/produce more interesting and novel plot lines. Avatar's plot is pretty easy to guess after the first 15 minutes - you've seen the same story as a Western. Plus of course the inevitable "boy gets girl, boy looses girl, boy gets girl back". Fortunately we are spared a long drawn out ending - the action is over and the heroes (well at least most) live happily ever after in prompt fashion. Worth seeing once - not twice.

Banks need to combat card skimming

noreply@blogger.com (Gregory Smith) — Mon, 19 Oct 2009 08:58:00 +0000

EFTPOS and credit card skimming has hit Western Australia big time. I'm sure the banks have been good enough to cover any genuine losses of their customers. After all, the amount skimmed is small for the banks - just a few million dollars. However, the worry and stress of those folks who have their accounts targeted must not be ignored.

I've noted that some banks offer a range of security enhancing alternatives, such as SMS one time passwords and security tokens which generate one time pass numbers. Unfortunately not all banks offer these. I would happily pay $20 or $30 dollars for a security id token, but my bank (Bankwest) only offers these to business customers.

In addition, the smart chip credit card is again only offered by a small number of banks, and is only available at a very small number of places.

Credit Card - Sign or PIN

Having noted that the card skimmers rely on copying the magnetic strip AND taking a photo of your PIN number, I've reverted to signing for my credit card purchases rather than using my PIN number. My logic goes like this - you need the PIN number to withdraw cash from an ATM. If you do not enter your PIN it cannot be copied. So given a choice of PIN or signature - I'm back to signing. This is unfortunate - credit card PINs were well overdue and are a much more convenient way to shop that signing lots of dockets.

Thomson Dick Smith/Tandy MP3 player good value

noreply@blogger.com (Gregory Smith) — Sat, 05 Sep 2009 04:50:00 +0000

On the topic of mp3 players - I sometimes go bushwalking for a few days, so a rechargeable MP3 player is no good. I need one powered by batteries.

I picked up a cheap MP3 player from Tandy/Dick Smith (same store these days). This Thomson model cost AUD$39 for 2GB, powered by AAA batteries. This model also has a slot for microSD cards up to 2GB, and an inbuilt USB plug (no need for cables). Once my first outing, a single AAA battery lasted about 12 hours.

Now I guess you can't expect much for $39 - but I was pleasantly surprised. The player works well, has reasonable sound quality, and the included earphones are not bad. My only complaint is that the battery cover comes off too easily and the microSD card cover doesn't fit properly. But it's my bushwalking player, so a couple of bits of electrical insulation tape fixed both problems - as well as improving it's resistance to minor splashes.

If you want a low cost, battery powered MP3 player - this one is not too bad.

Iriver E100 mp3 player a disappointment

noreply@blogger.com (Gregory Smith) — Thu, 27 Aug 2009 07:10:00 +0000

Looking to upgrade my mp3 music player, I started comparing features for largish capacity players. Somehow, I couldn't quite stomach the Apple/iTunes thing. The iRiver E100 looked attractive with a good price, 8GB + microSD memory and a standard 5 pin mini-usb connector.

In the back of my mind was that iRiver has been seen as a premium brand of mp3 players. So I took the plunge and was soon disappointed.

There are a few things to like about the E100 - expandable memory, good quality audio, reasonable battery life (17 hours) and a standard connector (I already have a draw full of all sorts of proprietary cables).

However the E100 is poorly implemented - it's firmware is so bad as to be disgraceful.

Firstly the unit is so sluggish in use it can be called generally unresponsive to everything except the most patient button presses.
Scrolling through any but the shortest of lists takes forever - the cursor moves one item every 1/2 second.
There were several bugs in the latest version - cannot disable fade-in / fade-out, and the sleep function does not work if the turn off time is after midnight.
Support from iRiver is non-existant - no response to my emails.
The button layout is non standard. Up and down change songs (not left and right).

On the hardware side, the design is a plain uninspiring black box. The user interface graphics are boring. Guys on the bus look over your shoulder and smirk at what appears to be a "beta" design at least. The buttons are not satisfying. They click but a fast response almost never happens. It is difficult to select the middle button without activiting on of the others. There are a couple of very small speakers - so small as to be useless.

IRiver really need to do something to rescue their reputation. At the very least, they should get some decent firmware written -

Make the unit more responsive to button presses and faster scrolling - even at the expense of music if processor power is limited.
Fix blatant firmware bugs inclusing fade-in/out disable and sleep timer.
Make the user interface more appealing.
User selectable button functions (so we can all go back to the standard left / right for songs).

I can't see myself buying another iRiver product.

PayPal Lessons in Losing Customers

noreply@blogger.com (Gregory Smith) — Wed, 02 Jul 2008 08:27:00 +0000

PayPal must think it has too many customers. It's arrogant to the point of radiance. My Firefox browser (2.0.0.15) stopped working with Paypal and I've checked every possible setting. It works with every other secure site I know. I've sent three emails requesting help and jumped through hoops filled in the forms on their so called help pages (using another PC) - but not even an automated response after 4 weeks.

The Paypal software / web page is not even that great. I've come unstuck a few times in the past - lost in an endless loop wondering if my transaction happened once, twice or multiple times!

As far as the buyer protection program goes - I can only relate experiences and frustrations of my friends saying "no result". So I haven't even bothered to try.

So Ebay and Paypal now enforce measures to "protect customer security" (read - "increase our own profits").

So Paypal Lessons are:

Promise everything - deliver nothing
Cut off large chunks of customers
Ignore customer comments and requests
Show your arrogance off

If a credible alternative appears Paypal will (and should) disappear in weeks.

Should There be a Ban on Incandescent Lamps?

noreply@blogger.com (Gregory Smith) — Wed, 02 Apr 2008 03:15:00 +0000

Here's an excellent article covering lots of technical issues regarding replacing standard incandescent lights with CFLs (Compact Fluorescent Lamp). Certainly worth a read. There are many issues and it's not as simple as saving energy (and sometimes you don't!).
http://sound.westhost.com/articles/incandescent.htm

Thank Goodness Daylight Saving Finished

noreply@blogger.com (Gregory Smith) — Mon, 31 Mar 2008 13:30:00 +0000

Thank God that daylight saving is over for another year in Western Australia. I know some people like it, but it's really doesn't sit well with me at all. It's unnatural! Only one more season until the pollies let us have a referendum to kick it out again.

And on the topic, can someone please explain to the pollies that changing the daylight saving dates at the last minute is really, really painful for all manner of computer systems - as demonstrated by the confusion in the Australian Eastern States deciding to extend by a week. Haven't the pollies ever heard of timezone files and what a pain they can be?

The WA pollies are saying that Daylight Saving may be shorter for WA next year because the mornings are too dark. But doesn't that argument make a huge mockery of a key reason - to reduce timezone confusion around Australia?

Shoddy work on Osram Compact Fluro Bulb

noreply@blogger.com (Gregory Smith) — Mon, 31 Mar 2008 13:17:00 +0000

A few weeks ago I bought a couple of warm white compact fluro bulbs for my office. Brand Osram -Duluxstar Minitwist 18W. Light tone is great and warm up time is minimal. However one of the bulbs started working intermittently - working some days and not others. I wasn't going to be bothered driving to the place of purchase to get it replaced (probably threw out the receipt anyway). But just before I binned it I thought - I wonder how hard this is to get open?

The answer was easy. The main body came apart using a flat blade screwdriver and minimal effort. Inside there is a neat looking circuit board and quite a few components. However on closer inspection I saw:

The transformer was not soldered flat to the board and it's weight had separated one of the PCB tracks from the board (see second picture for my solder bridge repair).
One other solder joint had cracked (on the main switching transistor).
Several other solder joints looked dry.

Naturally I fixed these problems in a couple of minutes with my soldering iron (don't try this at home kiddies!). I wouldn't recommend trying this repair unless you are qualified for electronic repairs and have the right tools.

But having to fix poor quality construction is always a bummer. Just a little better quality control would reduce Osram's costs enormously. Where are the hard won lessons of Japanese manufacturing quality control?

Great service - Inkjetwholesale.com.au

noreply@blogger.com (Gregory Smith) — Tue, 18 Mar 2008 04:15:00 +0000

Getting great service always deserves some acknowledgement.

Got the best price on a laser toner cartridge, ordered it over the net, paid with Paypal (my preference), got the emailed invoice and shipment confirmation, and it arrived from Sydney (to Perth) the next day. What more could any online customer ask for?

Inkjet Wholesale Pty Ltd - www.inkjetwholesale.com.au - gets my recommendation.

thewest.com.au site - Advertisement OVERLOAD!!!

noreply@blogger.com (Gregory Smith) — Thu, 13 Mar 2008 13:02:00 +0000

Being in Western Australia, my local newspaper and local news website is www.thewest.com.au. Traditionally has always been a reasonable site with good local information.

Of late, the site has become so overloaded with javascript and flash animated ads that it is virtually unusable - and certainly a strain on anything but the fastest PCs. Some pages have up to 15 separate animated ads.

I'm not saying that ads should not be used - after all it pays for my free viewing of the web page. But in the case of www.thewest.com.au, the geeks have taken charge and let the ad guys run amok with so many fancy and silly effects that it destroys the whole experience.

For instance, the home page gets plastered with an RAC ad that fills every corner (see picture), and takes so much processor resource to run that I can't even use the close button to get out.

Come on guys - get real! This is not smart - just stupid. It's not enticing me to consider the ad content - just putting me off the whole page (and the advertiser who is stupid enough to think its a great idea).

Until this gets fixed, I'll be avoiding this horrible site.

Vista NEEDS Memory

noreply@blogger.com (Gregory Smith) — Mon, 18 Feb 2008 10:34:00 +0000

Just in case there is any doubt.

I've just upgraded the laptop mentioned below from it's original 512MB to 1.5GB (added a 1GB card). Startup time has halved. Shutdown time is now one-fifth of the original. Word startup is one-third of time. Other applications are also much faster in startup and operation. Magic!! Best $69 you could ever spend. Installation took 5 minutes.

New laptop & Vista

noreply@blogger.com (Gregory Smith) — Sat, 16 Feb 2008 01:46:00 +0000

I needed a laptop for use "between jobs" (normally I get one provided at work). Didn't want to spend much money and didn't need anything too powerful. The Good Guys had a great deal on an Acer 4315 with Vista - price $669 less $149 Acer cashback = $550. This was $50 cheaper than Officeworks and other places. Done deal.

Celeron M 1.86Ghz, 512MB, 80GB disk (65GB useable (about 15GB hidden for recovery and windows re-install), DVD writer. I like the 14.1" screen - most budget laptops have bigger 15.4" screens - I hate big laptops and would buy a smaller one if I could justify the money. Windows Vista Home Basic (No Aero effects).

Screen is good, though brightness is not fully uniform - a little bit duller at the top. Performance with Vista is better than I expected - reasonably snappy response. Memory is always 100% and the thing goes swap crazy everytime you move the mouse - so I've already ordered an extra 1GB memory upgrade ($65 from upgradeable.com.au).

I'm no Microsoft fan at all - but I must admit that I am enjoying the Vista experience. A lot of things are in more sensible places than XP - settings are easier to get to. I like the on-screen "gadgets" (even though when you download then from the Microsoft site you get a warning saying that they may contain code that will wreck your PC and your life! - must be a really insecure framework). Apart from a re-arrangement of file layout (no more Documents and Settings), it's pretty familiar XP territory.

All in all - pretty happy with my purchase.

Experiences with Linux Gos Rocket

noreply@blogger.com (Gregory Smith) — Sat, 16 Feb 2008 01:07:00 +0000

I've played around with a number of linux distributions. My server runs Fedora with no "real" desktop - just mwm running on a raw X session. But I'm always on the look out for a decent desktop Linux solution.

Gos (Good Operating System) was released with a lot of fanfare, and it's second incarnation - Rocket - also received a lot of media attention. So I'm giving it a try.

Installation is quite easy, and it seems fast enough on my Celeron 1.1Ghz 320MB test machine. Most things fell into place straight away, though the bootup graphics are broken (seems to be some bad argument being passed to exquisite). Gos is pretty simply a base of Ubuntu with a highly customised "enlightenment" desktop. The customisations are good - especially the mac like launcher bar. Not liking the window border look, I quickly download "clearlooks" window decorations.

Things I like:

Groovy "mac like" launcher bar at the bottom.
Clean interface.
Different wallpapers on each desktop (why doesn't gnome have this??).
Pretty easy configuration of the screen to make things look the way you want.
Reasonable performer on my low-endish machine.
Synaptic package manager allows easy download and install of lots of Ubuntu compatible packages.

Things I don't like:

Some areas are still pretty buggy or incomplete (e.g. startup screens broken).
There appears to be no inbuilt facility to setup printers or network drives. I had to do these manually.
The standard file manager is horrid.
Little support - the user community is supposed to use FAQLY - which is horrible, doesn't easily allow discussion and doesn't help build a community.
No place to file bug reports (maybe they don't want to know).

Summary
Gos is getting there. I think there is still someway to go in stability and fine tuning. I enjoy using it, even though I go back to command line to file management functions. Worth a try.

USB Charger a waste of money

noreply@blogger.com (Gregory Smith) — Sat, 09 Feb 2008 10:36:00 +0000

Another little knick-knack I bought on Ebay was a USB charger for AAA and AA batteries. I wanted one that could charge a single battery (for my mp3 player) and this seemed to fit the bill. The seller was conquest_computers in the UK.

Item arrived ok, but the quality is really, really crap. No box, no instructions and one side stopped working after a few minutes. Disassembly showed that an internal wire had come off which I fixed myself (rather than returning the item to the UK). I admit if works (now), but I'd avoid this one. Looks good in the pictures but build quality is horrible,

Sucked in by EBay scam - hacked flash disks abound

noreply@blogger.com (Gregory Smith) — Sat, 09 Feb 2008 10:15:00 +0000

Having a bit of spare time on my hands - I thought I'd see if there were any bargains on EBay (horrible habit I know). Anyway, I came across fantastically cheap 8GB flash drives - hundreds of them going for between $20 and $40 AUS. I grabbed a couple of 8GB drives (one for $28 and the other for $17) and a 2GB as well for $10.

Well, of course the reason they are so cheap is that they are "hacked". Each of the drives appeared as the correct size in windows and linux, but the actual size was half (4GB instead of 8GB and 1GB instead of 2GB). The actual sizes were confirmed by testing writing files to the flash drive. Anything over the real capacity appeared to write, but couldn't be read back. New directories created in this non-existent space were non-accessible and could not be deleted. When I opened the drives and looked up the flash chip part number on Google, the actual size was confirmed.

Now these guys hack the drives so they appear twice the size, and you don't find out the truth until you fill the drive over half its capacity.

Am I upset? Not overly. I think a lot of people would be pissed off. However the prices I paid were still cheap for 4GB and 1GB drives. I guess it's better than losing my money by not getting anything at all. A friend suggested that these guys should advertise "50% off!" (being of course the capacity - not the price!). A look around Google shows that some people are much worse off - getting only 256MB capacity out of an "8GB" drive.

To fix the problem, I deleted the existing fake partition table and created new partition tables on the drives with just under half the supposed capacity - and of course removed the fake stickers. Windows and linux still report the 8GB capacity for the device, but show the drive having 3.8GB space available (which is the size of the partition tables I used.

For the record, the EBay sellers were shuqinlai998, kawayi998 and merci_online - all based in Hong Kong. Probably the same mob - its' so easy to setup a fake seller to get rid of a bunch of stuff, and then change the name when the truth comes out.

Live and learn. I guess what pisses my off the most is attitude of these dishonorable dickheads.

Australian Tax Office still a Microsoft monopoly supporter

noreply@blogger.com (Gregory Smith) — Mon, 21 Jan 2008 10:32:00 +0000

I recently applied for an ABN (Australian Business Number) on line at the Australian Tax Office site, but wasn't allowed to use the online system unless I was using Windows with Explorer or Netscape Navigator.

Hmmm..............

Anti-SPAM Adventures with Postfix

noreply@blogger.com (Gregory Smith) — Mon, 21 Jan 2008 09:45:00 +0000

You may remember that 2004 and 2005 were the years of the email virus. 2007 and 2008 are definitely the years of SPAM email.

I run a small home server with Postfix. It just does email for my self and immediate family members - about 12 or so accounts. It gets about 400 SPAM emails a day. This takes some filtering. What's interesting is how SPAM is changing.

Initially we had direct SPAM - a server would send out thousands (or millions of emails. These were easily blocked by IP address. Then we had open relay SPAM - an internet search would see what mail servers were mis-configured for relaying and emails would be directed through that server. Again reasonably easy to block, even so some legitimate emails might have been blocked.

Now we have zombie SPAM - virus infected computers are transformed into mail senders. You will see today that an IP will just send SPAM once and then you'll never see it again (presumably the owner sees his PC melting down and gets it fixed). So you can't block by IP because it's different all the time.

Email programs like Outlook and others try to filter SPAM on content (what the email actually says) or the sender email address. These are becoming more ineffective because the sender email address is made up and different every time, and content is so simple it's hard to filter (e.g. how do you filter something like: "she will feel better".

Fortunately much of the current type of SPAM can be filtered by a mail server (or more correctly an MTA) such as Postfix. However you need to know a bit about the email protocol (SMTP) and how it works.

Simply put, a sending computer (a client) sends an IP request to a mail server. After the IP conversation is started, the client should introduce itself with a HELO (or EHLO) command and it's name. It then identifies who the email sender is (e.g. MAIL FROM fred@fred.com) and who is to get the email (RCPT TO sue@sue.com).

The sending computer can be any random infected PC trying to act like a mail server, but it still has an IP address. This IP address can be looked up using reverse DNS to resolve a host name. Often the name will come up something like 211-34-56-78.dhcp.domain.com. Now a proper mail server will not have a name with "dhcp" in it. Proper email servers are unlikely to have host names with "cable" or "ppp" or "cpe" or "dynamic" or "adsl" in them. So if the ISP has configured reverse DNS correctly for his clients, such fake hosts can be pretty quickly filtered out.

If the DNS is not configured directly, a reverse DNS lookup will come up "unknown". Some significant companies (e.g. Commonwealth Bank in Australia) send email from servers with incorrect reverse DNS settings. In this case you can use Postfix access to allow IPs from email senders you know are genuine, and block others that are "unknown".

You can also block on the name announced in the HELO command. If an email uses HELO fred.com, Postfix can look up to see if fred.com actually really exists. About half the SPAM uses incorrect HELO statements that are easily filtered.

My next filtering stage is a custom filter (written in bash) with a whitelist of sender names and then a list of bad words and phrases. The whitelist of senders allows the badlist of words to be quite brutal because whitelisted senders will not have their emails filtered. Only unlisted senders are subjected to this filter. For instance, a badword is "Megadick". An email containing this word will be filtered if the sender is not on the whitelist. However if auntie jones sent an email with that word in it, that email will get through because auntie.jones@mydomain.com is in my whitelist.

All in all I have 7 stages of SPAM filtering - client checks, HELO checks, sender checks, postfix header checks, postfix body checks, postfix mime header checks, and my own filter script. The occasional SPAM email will still get through. But not for long. I'm on a mission !!!!!

For those that are interested - from /etc/postfix/main.cf:


# Following works on IP and resolved host
smtpd_client_restrictions = permit_mynetworks,
 check_client_access hash:/etc/postfix/access,
 check_client_access regexp:/etc/postfix/client_helo_checks.regexp,
 reject_unknown_client,
 permit

# Following works on string received in HELO
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks,
 reject_non_fqdn_hostname,
 check_helo_access regexp:/etc/postfix/client_helo_checks.regexp,
 reject_invalid_hostname,
 reject_unknown_hostname,
 permit

# Following works on MAIL FROM
smtpd_sender_restrictions = permit_mynetworks,
 check_sender_access hash:/etc/postfix/access,
 check_sender_access regexp:/etc/postfix/sender_checks.regexp,
 reject_non_fqdn_sender,
 reject_unknown_sender_domain,
 permit


header_checks = regexp:/etc/postfix/header_checks.regexp

mime_header_checks = regexp:/etc/postfix/mime_header_checks.regexp

body_checks = regexp:/etc/postfix/body_checks.regexp

Cheers,

Differences between Car GPS and handheld "real" GPS UNits

noreply@blogger.com (Gregory Smith) — Sat, 05 Jan 2008 03:52:00 +0000

Having been a user of handheld GPS units (my current is a Garmin Vista Cx - very happy with it), I was a bit disappointed with my first purchase of an in-car GPS navigator. I bought a Navman S80 for my wife.

The Vista handheld with City Navigator maps gives me routing and directions (not the most elegant but workable) as well as a host of other regular GPS device features such as track logs, easy creation of waypoints, routes, moving compass, trip computer, etc. However the Navman (and as far as I can see most in-car units) may be excellent navigators but don't provide things I am used to - e.g. offroad direction to destination, track logs, ability to enter waypoints and destinations by GPS co-ordinates, etc.

As a reasonably sophisticated user of GPS units I am a bit disappointed with the lack of fundamental GPS navigation tools in these in car units. I admit many users would never use these "features" - but not being able to enter a destination by GPS co-ordinates seems silly to me.

On the Navman itself - again a little disappointed. The screen is very washed out by daylight, the map update is quite slow compared by my handheld (you are some distance past an intersection by the time the map shows you at the same intersection), and the PC package is huge with little useful function. On the positive side, the directions seem to happen in time and are reasonably accurate.

Another issue I have with these in car units is that none of them seem able to offer monthly map updates for a reasonable price. It would be nice to subscribe to a service say for $10 a month and get map updates downloaded. At the moment you have to pay for a whole new map set (usually $150-$300) when your map gets too old. I can see Whereis/Sensis making a killing here.

New Telstra 3G Phone

noreply@blogger.com (Gregory Smith) — Sat, 05 Jan 2008 03:43:00 +0000

Well, with the impending closure of the Australian CDMA network, I finally bit the bullet and got a new 3G phone. I had been using a great and very simple Nokia phone (with glorious black and white lcd screen) for some time on a Pre-Paid.

After trying the Telstra phone up service (and finding the girl who answered didn't seem to know much about upgrading a CDMA PrePaid account to 3G!!!) I fronted at a Telstra shop - asking for the cheapest phone going. The Samsung A401 was offered for $99 and I took it - transferring my number and PrePaid credit over.

Although I don't generally like clamshell / flip phones, the Samsung A401 is a nice little unit - good screen and easy setup. No much else in it really - 640x480 camera and bluetooth is all - but I only want to make and receive calls. It's not rated for remote locations like the A411 and A412 - however it's a new phone with a new chipset - so hopefully will give adequate coverage. Maybe it hasn't been tested yet and coverage will be similar to the A411/412. Time will tell. At least being back on a SIM phone (CDMA doesn't use SIMs) I have some extra flexibility.

I'm not too much of a fan of Telstra's new PrePaid plans. I did like the older ones with cheap calls to mobiles on the weekends and 5c credit for every minute someone calls you.

Opposed to Daylight Saving in Western Australia

noreply@blogger.com (Gregory Smith) — Wed, 25 Oct 2006 01:56:00 +0000

Well, it seems the prospect of daylight saving being adopted in Western Australia is again on the cards. Three trials and three referendums over 20 years have seen the public oppose daylight saving, but the politicians and business people keep on pushing. I guess they'll keep on asking until the public responds with the "correct" answer - the one they want to hear.

To my mind, daylight saving is not needed in Western Australia.

We have about an extra 1/2 hour of daylight compared to Sydney and Melbourne anyway (being on the opposite edge of our timezeone).
It's a real pain for people outside of the city - those who start work at 5 or 6am.
Longer afternoons will increase rather than reduce power usage (power reductions were one of the old reasons for daylight saving - but hot afternoons and air conditioners has not reversed this arguement).

But the thing I dislike the most is the "as sure as God made apples" fact - once daylight saving is in, we'll never have a choice or referendum to get rid of it. The old "we'll keep on pushing until you (the public) give us what we want" and good ridance to any chance of any choice after that.

I'm voting no.