Now you have to be careful with MIG-23 and MIG-27s. MIG-23s, in Soviet Service, were intended to be fighter-bombers, while the MIG-27s were true fighters (The main difference was the much larger Radars for the MIG-27s, otherwise the planes were the same, and NATO treated both as the same with their NATO designation).
Now, while the Soviet MIG-23s were fighter-bombers, that did not mean the Libyan MIG-23s are fighter bombers The Soviet Union would sell what people wanted thus you could have MIG-27 capacity in something the Soviet called a MIG-23, on the other hand the MIG-23 sold to Libya could be aimed for ground support, it is hard to say given what we know of the Libyan Air Force)
More on the MIG-23:
http://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-23The SU-24 is an even older plane then the MIG-23, but as a all weather bomber sill used by the Russian Air Force (The MIG-23 have been eliminated from the Russian Air Force do to the cut back in that force since the 1980s, i.e nothing replaced the plane, the squadrons that flew them were eliminated). The SU-24 is a much more expensive plane to operate then the MIG-23 and other reports have stated MIG-23 ground attacks.
Both were aimed for operations against foreign forces in mass (Mostly anti-shipping i.e. aimed at the US Navy more then anything else). Slower Jets like the SU-25 and Helicopters will be more effective in the type of fighting that is occurring today i.e. small units fighting short intense fire fights NOT large units massed for a ground attack
More on the SU-24:
http://en.wikipedia.org/wiki/Sukhoi_Su-24Most MIG-23 along with older MIG-21s seems to have been grounded since the 1980s (do to lack of parts). Russia never supplied Libya with MIG-25s, thus the most effective weapon so far has been Helicopters (Both US and Soviet/Russian Helicopters)
More on the Libyan Air Force:
http://en.wikipedia.org/wiki/Libya_air_force