Beachcombing

A bit of an absence from updating the blog over the past month, due primarily to being busy with work/home.  I hope to get back to my regular cadence of something every week or so, and I’m going to start with something lighthearted.  There are several more technical articles I’ve got on the go, hopefully I’ll get those cleaned up and ready to post soon.

Late last summer we headed west to Vancouver Island, this is a regular trip as many of my relatives are out that way.  We took a break from visiting family and spent some time in Parksville, specifically down on Rathtrevor Beach.  The first morning we were there, I took a walk with my daughter as the tide was out.  Not five minutes from the cabin I came across a cell phone (pictured above) sitting on the wet sand.

Not seeing anyone around for literally miles, there was a very slim chance I was going to get this back to the owner.  I figured I’d see if it was in working shape or not.  Turns out it didn’t work, and was likely pretty water logged.  Popping it open let me determine the exact model number (Samsung SGH-J706), and based on the SIM card which revealed the carrier it appeared to be a pay as you go phone.

Things started to seem grim when I took a look at the charge port on the phone, not a great sign to see corrosion and salt build up.  It was pretty clear this was very likely junk, but I couldn’t just pitch it into the trash.  It ended up coming home with me where I got a chance to open it up [you could probably tell that was coming..]

The J706 is a slider phone, the screen slides up to reveal a keyboard underneath.  Pretty slick, and I can’t help but think back to The Matrix whenever I have one of these in my hand.  Disassembling the slider was educational, I was able to take it all apart – and put it back together.

Unfortunately, once I had it apart it was pretty clear this wasn’t ever going to work again.  I often wonder if its possible to repair phones that have gotten wet (you see these on eBay from time to time) but a good soak in saltwater looks like a one way ticket for electronics.  The LCD screen seems to have been fairly well sealed, and some of the parts may have been in a working state as well – but it should be evident from the photo that much of it was a complete write-off.

Reassembled and cleaned up, it looked cosmetically fine.  The slider mechanism worked smoothly too.  In the end, I took it into BestBuy’s cell phone trade-in program: I figured that at least they could recycle it properly.  I was up-front with them about the non-working condition of the phone, and they did check it for water damage (there is a little indicator under the battery usually).  The representative told me if it had been in working shape it was worth $60, I figured that was the end of the conversation and told him just to recycle it – but he stopped me and said, let’s see what I can give you for it.  Turns out it was worth $7.61 – I walked away with a gift card feeling pretty lucky.

Free Airport WiFi

Back nearly 2 years ago I wrote about the lack of “free” wifi at the Ottawa airport, I was pleased to find out they now offer free wifi. I’m not opposed to paying for wifi access, but most of the providers charge more than I’m willing to pay.  If it’s not free then I think the Starbucks model of buy something (a coffee card) and get access is a great way to go.

As you can see from the image, there is still an optional pay service at YOW – but the free one is clearly marked.  I ran a quick speedtest that showed 186kbps down / 26kbps up – not very fast but I don’t expect much for free.  It worked well enough to check twitter and get to my web mail.

For this trip, I was headed to Florida.  The Orlando airport (MCO) also has free wifi, currently it is supported by Google through the holiday season but it is always free.  I’ve been in several US airports which also have free wifi year round, and given that you’ll likely end up waiting around for your flight having internet access is a great way to while away the time.

Ideally any location you end up waiting in for some undetermined amount of time should have (very) cheap or free internet.  My car dealership has free wifi in the waiting area, why not extend this to doctors offices, bus stops, train stations, banks, etc?  Imagine if the government decided that all of its public service centers (think passport office) would have free wifi – I’d be way more willing to sit patiently and wait.

One last note – I’d like to recommend the WiFi Get app for the iPhone/iPod Touch. I think it’s a must have app if you travel with your device.

Earning Trust for Your Email Server

I host my own email server, this in itself is a very odd thing to do in this day and age.  If you want email to come from your domain, Google offers this for free and provides the same interface as Gmail. If you insist on running your own mail server, then setting it up to use your ISP as a smarthost is the easy way to go (very easy with Ubuntu), of course I didn’t take that path.

As an aside, setting up a mail server that uses fetchmail to gather email from the various accounts you have, and using a smarthost configuration to send email does give you most of the benefits of running your own mail server with very few headaches.  The reason to do this might be that you don’t want to trust Google (or someone else) to hold all your email, and/or you don’t want the individual PCs in your house to be the storage for your email (hard to migrate to a new machine, recover from disaster).  This is how I started down the path of running my own true email server. [I keep thinking that someone should create an easy to install NAS add-on that provides exactly this type of email server]

Ok, maybe you don’t want to run your own email server but you’re interested in knowing what is involved… Having a static IP address is handy, mostly to save you from DNS issues.  While you can manage to have a domain name tied to a dynamic IP, many blacklists include the IP ranges used by ISP for dynamic addresses.  Of course you need a domain name, and a DNS server too.  You might also want to consider a secondary MX record, in case your connection goes down.  You’ll also want to check that your ISP isn’t blocking port 25 outgoing, and having a valid reverse DNS is important too.

So you’ve followed the Ubuntu documentation and setup a mail server, great.  Assuming your IP address is “clean” (ie: not on a blacklist), then you can probably send email just fine.  Until you start hitting problems where spam filters have taken a dislike to your system – in my case it was Rogers (email provided by Yahoo) that treating my outgoing as spam.  One solution is to have the recipient add your email address to their address book so they do still get to see your email.  It may still get tagged as [Bulk] but it won’t get lost.  This isn’t a great solution for someone new you want to contact, or a friend who isn’t terribly technical.

It turns out there are some additional measures you can take on the email server side to add more trust.  There are three I’ve implemented:

All of them rely on the same basic ‘trick’ of adding a TXT record to your DNS information that serves to validate the email.  This works for the simple reason that spammers tend to use botnets made up of machines without valid DNS records.  SPF simply is a declaration that the IP address sending the email is allowed to send email for the specified domain.  DKIM is an updated version of DomainKeys, but both can be used concurrently and some systems only know one.  Both DKIM and DomainKeys have the email server sign the email with a secret (private) key, and the DNS record has a public key that will validate the signature.

After implementing all three, it turns out Yahoo was still tagging my email as spam.  Very frustrating.  One solution I did consider was to avoid the problem entirely and selectively smarthost email going to rogers.com (and yahoo.com, etc).  In the end, it turns out that Yahoo maintains their own blacklist of sorts and you can request to be removed.  To check this, you need access to a yahoo email account that you can send test messages to.  By examining the header you will see X-YahooFilteredBulk if your IP is on their blacklist, this appears to be independent of the status of your SPF/DKIM/DomainKeys authentication that should show as a pass.  The solution is to fill in the Yahoo form, and be persistent.  Much of the form will not apply but you do need to fill it in with something reasonable (and valid).  After a couple of exchanges over several days I was rewarded with this reply:

While we cannot fully exempt your mail server from our SpamGuard
technology, we have however, made appropriate changes to this IP address
in our database. This should help with delivering mail to the
appropriate Yahoo! folders.

Now email sent to yahoo.com is not tagged as spam or [Bulk] – I did a little victory dance once this happened.

The remainder of this post goes into some of the details of getting the three (SPF, DKIM, DomainKeys) implemented.

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