Vagrant起動時のSSH libraryエラー解消法

Vagrant起動時にSSH libraryのエラーがでて、Vagrantが起動できない時があります。

An error occurred in the underlying SSH library that Vagrant uses.
The error message is shown below. In many cases, errors from this
library are caused by ssh-agent issues. Try disabling your SSH
agent or removing some keys and try again.

If the problem persists, please report a bug to the net-ssh project.

timeout during server version negotiating


vb.customize ['modifyvm', :id, '--natdnshostresolver1', 'on']

参考URL Vagrant up takes long time after installing guest additions manually in centos box #6812