到达 ssh 部分时 vagrant up 失败：
myterminal$ vagrant up
[default] VM already created. Booting if its not already running...
[default] Running any VM customizations...
[default] Clearing any previously set forwarded ports...
[default] Forwarding ports...
[default] -- ssh: 22 => 2222 (adapter 1)
[default] -- db2: 30003 => 30003 (adapter 1)
[default] Cleaning previously set shared folders...
[default] Creating shared folders metadata...
[default] Booting VM...
[default] Waiting for VM to boot. This can take a few minutes.
[default] Failed to connect …