“In fact, the only rebel factions still strong enough to resist and fight the regime on the latest fronts are the radical Islamists. The town of Azizeh, just outside the Marjeh area in the east, the strategically vital Sheikh Najjar industrial zone, the old city and Aleppo’s central prison are all defended by al-Qaeda’s affiliate, Jabhat al-Nusra, as well as Salafist militants Ahrar al-Sham, a member of the Islamic Front.”
http://www.al-monitor.com/pulse/originals/2014/02/barrel-bombing-syria-aleppo-rebels-regime-war.html