I'm at Cairo-Egypt, so my Linux machine switched the time from GMT+2 to GMT+3 just this night as it does each year at this date, for the DST starts today. But in Cairo that DST was canceled just this year, and this affects systems everywhere to report Cairo's time incorrectly ( past one hour than it is acually ) I tried to modify the file /usr/share/zoneinfo/Africa/Cairo to reflect those changes but it's in a binary structure and no clues to understand it. Any suggestions?
The timezone data is provided by your distribution. For Debian/Ubuntu, the package is named
Incidentally, if for some reason you need to modify or create a binary timezone file, the source data and the tools to compile it to the binary files are hosted here with some basic instructions here (along with a lot of other information about time zones in general).