There is a graphical tool in Fedora that lets you define the timezone you live in. The effect of the tool is to change the file /etc/localtime to point to the appropriate file in /usr/share/zoneinfo. You can achieve the same thing by manually linking your timezone file into /etc like this:-
ln -s /usr/share/zoneinfo/Asia/Tehran /etc/localtime
The Tehran file should have been created with daylight savings in mind.