We have looked closer at this attack, and can conclude that China is using their active and passive network infrastructure in order to perform a man-on-the-side attack against GitHub.
more here.....http://www.netresec.com/?page=Blog&month=2015-03&post=China%27s-Man-on-the-Side-Attack-on-GitHub
more here.....http://www.netresec.com/?page=Blog&month=2015-03&post=China%27s-Man-on-the-Side-Attack-on-GitHub