環境 ホストOS: Xubuntu16.04.1(ただしOS関係なく起きる模様) ゲストOS: CentOS7 Vagrant: 1.8.5(これが主な原因) VirtualBox: 5.1 $vagrant up ほげほげ(省略) default: Warning: Authentication failure. Retrying... default: Warning: Authentication failure. Retrying... default: Warning: Authentication failure. Retrying... default: Warning: Authentication failure. Retrying... default: Warning: Authentication failure. Retrying... Timed out whi