Vagrantup時に、SSH auth method: private keyでタイムアウトになる

##環境
ホスト

Windows10 Home 64bit
メモリ 8GB
CPU i5-7400 3.0GHz
OracleVisualBox　5.2
vagrant 2.0.1
セキュリティーソフト：Windows Defender

ゲスト

CentOS6.4 x86_64

##導入経緯
もともと開発環境としてノートPCをメインで使用していたのですが、かなり不調で業務に支障をきたしていたため、PCを新調しました。この端末に、仮想環境の構築をするに至りました。

##症状

txt
1C:\vagrant\centos64>vagrant up
2Bringing machine 'default' up with 'virtualbox' provider...
3==> default: Clearing any previously set forwarded ports...
4==> default: Clearing any previously set network interfaces...
5==> default: Preparing network interfaces based on configuration...
6    default: Adapter 1: nat
7==> default: Forwarding ports...
8    default: 22 (guest) => 2222 (host) (adapter 1)
9==> default: Booting VM...
10==> default: Waiting for machine to boot. This may take a few minutes...
11    default: SSH address: 127.0.0.1:2222
12    default: SSH username: vagrant
13    default: SSH auth method: private key
14Timed out while waiting for the machine to boot. This means that
15Vagrant was unable to communicate with the guest machine within
16the configured ("config.vm.boot_timeout" value) time period.
17
18If you look above, you should be able to see the error(s) that
19Vagrant had when attempting to connect to the machine. These errors
20are usually good hints as to what may be wrong.
21
22If you're using a custom box, make sure that networking is properly
23working and you're able to connect to the machine. It is a common
24problem that networking isn't setup properly in these boxes.
25Verify that authentication configurations are also setup properly,
26as well.
27
28If the box appears to be booting properly, you may want to increase
29the timeout ("config.vm.boot_timeout") value.

と、まぁ認証しなくてタイムアウトでエラーになります。
結果は同じだろうと思いつつも、違うVagrantboxを追加しましたが同様の症状となりました。

##試したこと

vagrant upで失敗する原因が鍵不一致の場合の対処法

→ そもSSH接続できないんだから、書き換えられなくない・・・？と途中で気づいて中断

vagrant upでprivate keyより先に進まない症状

→ ゲストに./sshディレクトリがなかった・・・。homename直下にpublic_keyがあったので、そこを上書きしてみましたが、効果なし

vagrant up実行時にdefault: SSH auth method: private keyと表示されフリーズした時の対処法

→ 下記をvagrantfileに追記しても効果なし

config.vm.provider "virtualbox" do |vb|
    vb.customize ["modifyvm", :id, "--cableconnected1", "on"] 
end

VirtualBox にて E_FAIL (0x80004005) のエラーが出て VM が起動しない場合の対処

→ VMでマシンをクリックするとこのエラーが表示されたため、VMとVagrantを再インストールしたけど効果なし。

ポート指定しよう！

→ デフォルトで設定されている 22 ⇒ 2222 を適当なポート番号に書き換えたけど効果なし

Virtualization Intel VT-x/AMD-Vが無効になってる？

→ Enabled 有効でした。

ホストのファイアーウォールを無効にする

→ 効果なし

##Vagrantfile
Box名が違いますが、このファイルで試行錯誤してました。

txt
1# -*- mode: ruby -*-
2# vi: set ft=ruby :
3
4# All Vagrant configuration is done below. The "2" in Vagrant.configure
5# configures the configuration version (we support older styles for
6# backwards compatibility). Please don't change it unless you know what
7# you're doing.
8Vagrant.configure("2") do |config|
9  # The most common configuration options are documented and commented below.
10  # For a complete reference, please see the online documentation at
11  # https://docs.vagrantup.com.
12
13  # Every Vagrant development environment requires a box. You can search for
14  # boxes at https://vagrantcloud.com/search.
15  config.vm.box = "CentOS60-Re"
16
17  # Disable automatic box update checking. If you disable this, then
18  # boxes will only be checked for updates when the user runs
19  # `vagrant box outdated`. This is not recommended.
20  config.vm.box_check_update = false
21
22  # Create a forwarded port mapping which allows access to a specific port
23  # within the machine from a port on the host machine. In the example below,
24  # accessing "localhost:8080" will access port 80 on the guest machine.
25  # NOTE: This will enable public access to the opened port
26  config.vm.network "forwarded_port", guest: 80, host: 8888
27  config.vm.network "forwarded_port", guest: 22, host: 2223
28  config.vm.network "forwarded_port", guest: 3306, host: 3306
29
30  # Create a forwarded port mapping which allows access to a specific port
31  # within the machine from a port on the host machine and only allow access
32  # via 127.0.0.1 to disable public access
33  # config.vm.network "forwarded_port", guest: 80, host: 8080, host_ip: "127.0.0.1"
34
35  # Create a private network, which allows host-only access to the machine
36  # using a specific IP.
37  # config.vm.network "private_network", ip: "192.168.33.10"
38
39  # Create a public network, which generally matched to bridged network.
40  # Bridged networks make the machine appear as another physical device on
41  # your network.
42  # config.vm.network "public_network"
43
44  # Share an additional folder to the guest VM. The first argument is
45  # the path on the host to the actual folder. The second argument is
46  # the path on the guest to mount the folder. And the optional third
47  # argument is a set of non-required options.
48  # config.vm.synced_folder "../data", "/vagrant_data"
49
50  # Provider-specific configuration so you can fine-tune various
51  # backing providers for Vagrant. These expose provider-specific options.
52  # Example for VirtualBox:
53  #
54  config.vm.provider "virtualbox" do |vb|
55  #   # Display the VirtualBox GUI when booting the machine
56    vb.gui = false
57  #
58  #   # Customize the amount of memory on the VM:
59    vb.memory = "1024"
60    vb.customize ["modifyvm", :id, "--cableconnected1", "on"]
61  end
62  #
63  # View the documentation for the provider you are using for more
64  # information on available options.
65
66  # Enable provisioning with a shell script. Additional provisioners such as
67  # Puppet, Chef, Ansible, Salt, and Docker are also available. Please see the
68  # documentation for more information about their specific syntax and use.
69  # config.vm.provision "shell", inline: <<-SHELL
70  #   apt-get update
71  #   apt-get install -y apache2
72  # SHELL
73end
74