In Visual Studio 2015, using bower, my package restores fail when behind a firewall with an error similar to:
ECMDERR Failed to exec
If you want a global solution.
WARNING: it can impact several proxy settings through different application but it certainly what you want :)
NOTE If you have special characters in your username:password in your proxy settings, you need to URLENCODED them. Example: http://DOMAIN%5Cuser+name%3AP%40%24%24w0rd@proxy.server.com:8080
You must add 2 environment variable.
To do that on windows 10: