$ composer create-project symfony/framework-standard-edition xxx
Installing symfony/framework-standard-edition (v2.6.0)
<...>
  - Installing symfony/symfony (2.6.x-dev 09d1a15)
    Cloning 09d1a15efe18945bb97fac3adc74d56b3bfd42f4
    Failed to download symfony/symfony from source: Failed to clone git@github.com:symfony/symfony.git via git, https, ssh protocols, aborting.

- git://github.com/symfony/symfony.git
  fatal: unable to connect to github.com:
  github.com[0: 62.192.255.178]: errno=No route to host