Friday, 19 August 2011

iPhone3G SSL bug fix

If you've got an old iPhone 3G and you've heard about the SSL bug which Apple don't seem interested in fixing for older iPhones then here's a fix - though you've gotta be running a jail broken iPhone. This bug is a bit nasty as it means that you could potentially be misled into connecting to a site that you think is a trusted site (e.g. your bank) but in actual fact it is a scam site. This can occur due to the fact that the iPhone's SSL stack doesn't check any site's SSL certificate properly - and the certificate is normally the thing that tells you you're connected to who you think you are.

Apple have recently released a fix for newer iPhones/iPads in iOS 4.3.5, but if you've got an old iPhone3G then the latest version of iOS it can run is 4.2.1 so you're a bit stuck. So since Apple isn't bothering to provide any more updates you might as well bite the bullet and jail break your phone - then at least you can add some more features and updates. I found redsn0w 0.9.6rc18 to do the job quite well after many failed attempts with greenpois0n.

Once you have jailbroken your phone you need to run Cydia and search for iSSLfix and install it (as also explained here) - then you're covered.

[updated:17feb12: Corrected problem description]

Tuesday, 16 August 2011

Converting video for DVD players

Most of today's DVD players will not only playback normal MPEG2 DVD video discs (i.e. normal DVDs) but also other video formats that allow for much more video to be packed onto a writable DVD disc like DIVX and XVID. They are actually very similar formats and are basically ISO MPEG4 video (which is closely related to ITU-T's H.264 video standard). There are loads of dodgy commercial tools out there for conversion but you can do it easily using the very powerful ffmpeg tool (it runs on MacOSX, Windows, Linux and others). So to convert something (e.g. an MP4 video named video.mp4) to XVID use:

ffmpeg -i video.mp4 -vcodec libxvid -b 800k vid-xvid.avi

This says compress it using the libxvid codec and set the bandwidth to 800kbits/sec - which looks ok whilst still compressing well - feel free to play with this though don't too high (e.g above 5Mb/s) as DVD players can have trouble playing it back. The name of the output file is vid-xvid.avi. I have found this format to be slightly better supported, although it slower to convert than the DIVX.

If you want to compress to DIVX use the following:

ffmpeg -i video.mp4 -vcodec mpeg4 -vtag divx -b 800k vid-divx.avi

This says use the mpeg4 codec to compress and mark the output video with the DIVX fourcc tag which will let the DVD player know it is DIXV video.

The the file can be burned to a DVD using your favourite DVD burner app - usually using the operating systems default one. To make it easier on the DVD player use names with 8(.3) characters that are then followed by the .avi suffix.

[14sept11: Corrected some minor errors]

Friday, 12 August 2011

Post mortem: IPv6 Day

The day seemed to go pretty smoothly in general. Whilst a lot of the main contenders switched IPv6 off again, it was said that 2/3 actually maintained IPv6 functionality after the day (see IETF talk below). Well when I say they switched it off - The visible aspect was to remove their IPv6 addresses (their AAAA records) for their main sites from the Internet's Domain Name Service (DNS) again. However a lot of work went on under the hood: Lots of web helper stuff to notify people if there was a problem, Various mods to custom code, and various dual stack proxies and some tunnels to provide IPv6. The main players do have IPv6 versions of their sites accessible both before and after the day - only they're either on a separate domain name (e.g. A number of these folks put up their own post mortem analysis pages (yes some of them did use some 1337 Hack0r IPv6 names;) : FACE::B00C, Google, C:15C0:D06:F00D, ISOC.Though probably the most in-depth analysis was provided in a presentation (by a combination of key players) at the IETF81 in July at Quebec, with good coverage from Arstechnica.

It seems that there are browser tricks to speed up IPv6 failover and now even OS level approaches to provide for it - notably OSX Lion has introduced some new black magic for IPv6 path selection.