My solution turned out to be none of the above exactly. I'm running Ubuntu 14 as guest inside a Windows 7 host. I had been running this vagrant box fine, but I started it up again after not using it for a couple of months, and it kept coming up with the SSH connection timeout. It turned out that somehow the key pair didn't work - so I copied the Vagrant public key into Ubuntu according to the instructions on this page. But that wasn't all. I then discovered that the private key in my base box was different than the private key here. Putting this private key in as the vagrant_private_key file in C:\Users\your-user.vagrant.d\boxes\vagrant-box-name\nnnnnnnn\virtualbox after placing the public key into Ubuntu fixed the problem.

It used to help to switch to trusty32, but the situation now got worse again: I tried to use Homestead 2.0 and now I've got the Connection Timeout problem again, which would't usually be a problem, because switching to 32bit helped before. But now I can't just add a line like config.vm.box="ubuntu/trusty32" because we don't have a classic Homestead.yaml file anymore, the values in the new 2.0 Homestead.yaml file just seem to be inserted into the real one in the background and there ist no Vagrantfile available that I could manually edit ...

希望有人能帮忙……

我通过在/etc/fstab中添加一个新条目来测试我的vagrant VM中挂载的文件夹。后来我注销了，跑了个流浪汉，但当我跑了个流浪汉，我得到:

SSH auth method: private key
Warning: Remote connection disconnect. Retrying...

I read all these posts and tried all the ones that seemed relevant for my case (except for vagrant destroy, which would have certainly fixed my problem, but was a last resort in my case). The post by @Kiee gave me the idea to try to boot my VM directly from the VirtualBox GUI. During the boot process the VM halted itself and was asking me if I wanted to skip mounting the test folder that I had added earlier to /etc/fstab. (That's why vagrant couldn't boot the VM.) After answering 'NO' the VM booted no problem. I logged in, removed the naughty line from my fstab, and shutdown the VM.

在那之后，流浪汉就能很好地踢足球了。

外卖吗?如果突然间vagrant无法引导回您的VM，请尝试直接从提供商引导(在我的情况下是VirtualBox)。您的引导可能挂起了与SSH完全无关的东西。

我也遇到过同样的问题，但是上面提到的解决方案都不适合我! 我通过将Vagrant降级到1.6.2来解决这个问题，现在它可以工作了!

我解决这个问题的方法在这篇文章中没有提到，所以我把细节贴在这里，以防它能帮助到其他人。

造成这种情况的原因是，在机器启动后，流浪汉无法登录机器。造成这种情况的原因有很多，正如本文中提到的，比如机器无法一直启动，或者iptables防火墙阻止SSH。

在我的例子中，问题是我无意中设置了一个“private_network”，它的IP地址与内置的VirtualBox NAT网络(在我的例子中是10.0.2.0/24)在同一个子网中。这打乱了机器的NAT网络(但没有任何地方显示错误)，由于vagrant通过NAT网络连接，因此即使机器正在运行且没有启用防火墙，它也无法连接。

Vagrant.configure("2") do |config|
  config.vm.network "private_network", ip: "10.0.2.31"
end

解决办法是更新我的VagrantFile，并使用一个与VirtualBox的NAT网络不冲突的“private_network”IP。

Vagrant.configure("2") do |config|
  config.vm.network "private_network", ip: "10.0.4.31"
end

就像有些人已经指出的那样，如果VirtualBox映像没有正确引导，就会出现错误。对我来说，在《Vagrant》中使用GUI模式并没有太大帮助，因为它只显示一个黑色窗口。在virtualbox GUI中，我检查了虚拟机的设置，发现操作系统设置不正确(Debian 32而不是64位)。

所以我只能建议手动检查虚拟机的VirtualBox设置，让虚拟机启动，而不是首先使用Vagrant。