[1] Uncheck "Settings > Wireless controls > Mobile networks > Data roaming". For good measure I also turned off background data usage, "Settings > Data synchronization > Background data", and disabled automatic refresh in all installed apps that gave me the option to do so.
T-Mobile G1 Requires Data to Make Calls and Send Texts
A cautionary tale: I took my T-Mobile G1 (aka HTC Dream) on a trip abroad recently. As I didn't want to pay exorbitant data roaming charges, I turned off all data access on the phone[1] before I left for my trip. While abroad I did make a few phone calls and sent and received some text messages. However, upon returning I discovered that my T-Mobile bill did have data roaming charges, in addition to the expected voice and text message roaming charges.
The data roaming charges were minor—it was quite obvious that the phone wasn't pulling down its usual smorgasbord of daily data—and surprisingly regular—each of the handful of line items on my bill was a multiple of 0.0244 MB. After much polite arguing with a T-Mobile representative, an explanation emerged: If a data connection is available, the G1 will use it when establishing phone calls and sending text messages. It will do so even if all other data access is disabled on the phone. The T-Mobile rep claimed that this is an optimization that allows the G1 to make a "better" connection to the cell tower. As proof she pointed out that each data roaming line item on my bill matched up with a voice call or text message (this was generally true but did require a bit of squinting with one eye closed for the data to actually match as she claimed).
I'm still a bit skeptical of the explanation I received from T-Mobile. But, while I haven't heard of GSM-based phones sending/receiving data while dealing with voice calls or text messages, it sounds plausible and somewhat matches the tiny amount of data that my phone actually consumed.
Numbers everyone should know
"Numbers everyone should know", courtesy of Jeff Dean:
* L1 cache reference 0.5 ns * Branch mispredict 5 ns * L2 cache reference 7 ns * Mutex lock/unlock 100 ns * Main memory reference 100 ns * Compress 1K bytes with Zippy 10,000 ns * Send 2K bytes over 1 Gbps network 20,000 ns * Read 1 MB sequentially from memory 250,000 ns * Round trip within same datacenter 500,000 ns * Disk seek 10,000,000 ns * Read 1 MB sequentially from network 10,000,000 ns * Read 1 MB sequentially from disk 30,000,000 ns * Send packet CA->Netherlands->CA 150,000,000 nsSimilarly (and courtesy of Jeff Dean and Sean Quinlan), "The Joys of Real Hardware" lists the typical problems a new cluster will experience in its first year:
- ~0.5 overheating (power down most machines in <5 mins, ~1-2 days to recover)
- ~1 PDU failure (~500-1000 machines suddenly disappear, ~6 hours to come back)
- ~1 rack-move (plenty of warning, ~500-1000 machines powered down, ~6 hours)
- ~1 network rewiring (rolling ~5% of machines down over 2-day span)
- ~20 rack failures (40-80 machines instantly disappear, 1-6 hours to get back)
- ~5 racks go wonky (40-80 machines see 50% packet loss)
- ~8 network maintenances (4 might cause ~30-minute random connectivity losses)
- ~12 router reloads (takes out DNS and external vips for a couple minutes)
- ~3 router failures (have to immediately pull traffic for an hour)
- ~dozens of minor 30-second blips for dns
- ~1000 individual machine failures
- ~thousands of hard drive failures
Getting out of a full-screen Citrix session in Linux
If you're running the Citrix ICA client under Linux and your Citrix session runs in full-screen mode, you can press Ctrl-F2 to pass the following keystroke to the host Linux desktop rather than the Citrix session. For example, if the Citrix session is connected to a Windows desktop, then pressing Alt-Tab in full-screen mode will normally send the Alt-Tab to Windows. Pressing Ctrl-F2 followed by Alt-Tab will send the Alt-Tab to the Linux desktop instead.
Creating a myopenid.com SSL certificate to use on your phone
www.myopenid.com is an OpenID provider that allows logging in via an SSL certificate saved in your web browser rather than by typing in a password. From a normal web browser you can just click on the "Create Certificate" button on their "Authentication Settings" page and your browser talks to the myopenid.com website and gets a certificate that it then stores in its local certificate store. Unfortunately the web browser in my Nokia E51 cell phone (a Series 60 WebKit fork) doesn't seem to support generating the certificate request when you click on "Create Certificate".
To get around this:
To get around this:
- Go to the www.myopenid.com "Authentication Settings" page from Firefox on your desktop computer. Generate a new certificate like you normally would (except that you probably want to name it after your phone).
- Once it's done note the serial number listed for the new certificate under the "Manage Your SSL Client Certificates" heading.
- Then open Firefox preferences and go to "Advanced > Encryption > View Certificates > Your Certificates".
- Find the *.myopenid.com certificate in the list that has the matching serial number and click "Backup...".
- Firefox will now prompt you for a file to save the certificate in, a password to protect that file with (you'll have to type this one in on the phone), and maybe your Firefox master password (depending on your settings).
- Now you have the certificate in a file. Find the file whereever you saved it to and use your favorite method of sending it to the phone. I just sent it via bluetooth but you should also be able to use email, SMS, USB, etc.
- Open the file on your phone. The phone will prompt you for the password you used to protect the file when you saved it in Firefox.
- From here the procedure varies by phone. For my S60 3rd Edition FP1 phone, the phone told me that it found one private key and one personal certificate in the file and asked me if I'd like to save them to the phone's key store. Since I hadn't used the phone's key store before, it also asked me to set a password for the key store. Then it saved the certificate and private key.
- After the above is all done, you can delete the file from your phone and from your computer.
- Since Firefox should have its own certificate to authenticate to www.myopenid.com, you can now delete this certificate in Firefox (only the one that you backed up, not all of your *.myopenid.com certificates!) using the aptly-named "Delete..." button.
- If you now go to www.myopenid.com in your phone's web browser and select "Sign in with an SSL certificate", the phone should use the new certificate and you shouldn't need to enter your www.myopenid.com password.
- If you want to verify that the certificate made it to the right place, and you're on a S60 3rd Edition FP1 phone, go to "Tools > Settings > General > Security > Certificate management > Personal certificates". You should see your *.myopenid.com certificate listed there.
Flying in Europe
I'm planning a trip to Barcelona, Spain and Birmingham, UK right now and figuring out the best way to get from one to the other is surprisingly difficult.
If money doesn't matter, then it's relatively easy to find a flight on any of the major airline booking websites. But be prepared to 1) spend 4-5x as much money and 2) be stuck with weird, long connections as there aren't many direct flights from Barcelona to Birmingham.
The answer is to fly one of the myriad discount airlines. The problem though is that there's no centralized website that lets you search the tickets of all of these discount airlines from one place. A few different websites try (e.g. www.wegolo.com, www.sidestep.com, www.skyscanner.com), but none of them have complete coverage of all airlines (or even complete coverage of any one airline it seems). Furthermore, even with the discount airlines, there's still a dearth of direct flights. So you end up planning a flight to a nearby city and connecting by train. But now you have to start scouring the map for all of the airports within 1-2hr train ride of your destination. And there's no website that's designed for that.
Is it so much to ask for a comprehensive and thorough multi-modal transportation website that will tell me the fastest, cheapest, and most hassle-free way to get from point A to point B anywhere in the world using whatever combination of airplanes, trains, buses, ferries, etc. is most suited to the task and within my constraints of departure/arrival times?
Nokia E51 + OS X + T-Mobile
i got my new nokia e51 setup to access the internet from the phone, paired it with my mac, and got the mac setup to connect to the internet via the phone over bluetooth. but every time i tried to connect the mac would complain about not being able to contact the ppp server.
it took me a bit to figure out the one extra step needed. the e51 (and probably other series 60 3rd edition phones) requires you to enter the access point name to be used for tethered connections (i.e. computer via bluetooth) separately from the access point name to be used for connections originating on the phone. even though in practice both of these names are going to be the same.
in short, after everything else you need to do to configure the phone and the laptop for tethered access, go to "Settings > Connection > Packet data > Access point" on the phone and enter "internet2.voicestream.com" (or "internet3.voicestream.com" or whatever access point you're using). this should be the same string as what's under "Settings > Connection > Access points > T-Mobile Internet > Access point name".
6to4 IPv6 on OSX 10.4 is a no-go
you'd think something like this would've been caught before release, but it turns out that all current versions of osx 10.4 have a byte order bug that causes 6to4 tunnels to be setup with the wrong address. when the machine's ipv4 address is converted to an ipv6 6to4-style address, osx incorrectly reverses the bytes, resulting in a useless address :(
more info at apple's ipv6 list
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