I am using Bower to install several libraries. For demonstration purposes here, I am installing bootstrap. Regardless of the package, I receive the following errors:
Are you behind a firewall?
Git doesn't pick up the proxy configuration when it's called, so set environment variables explicitly, e.g.:
export HTTP_PROXY=http://username:password@proxyserver:port/
export HTTPS_PROXY=http://username:password@proxyserver:port/
If your corporate proxy doesn't need authentication just omit the username:password@ bit in the URLs.
It worked for me!