安装grpc被墙

package google.golang.org/grpc: unrecognized import path "google.golang.org/grpc"(
https fetch: Get https:
dial tcp 216.239.37.1:443: i/o timeout)

git clone https://github.com/grpc/grpc-go.git $GOPATH/src/google.golang.org/grpc
 git clone https://github.com/golang/net.git $GOPATH/src/golang.org/x/net
 git clone https://github.com/golang/text.git $GOPATH/src/golang.org/x/text 
 go get -u github.com/golang/protobuf/{proto,protoc-gen-go}
 git clone https://github.com/google/go-genproto.git $GOPATH/src/google.golang.org/genproto

 cd $GOPATH/src/
 go install google.golang.org/grpc