Cannot install from local source

[allenwyma]

i have the gem file I downloaded from Rubygems.org, but it doesn't seem to like when i try to install it?

$ vagrant plugin install ./vagrant-proxyconf*.gem --verbose
Installing the './vagrant-proxyconf-1.5.2.gem' plugin. This can take a few minutes...
Warning: this Gemfile contains multiple primary sources. Using `source` more than once without a block is a security risk, and may result in installing unexpected gems. To resolve this warning, use a block to indicate which gems should come from the secondary source. To upgrade this warning to an error, run `bundle config disable_multisource true`.
The plugin 'vagrant-proxyconf' could not be installed because it could not
be found. Please double check the name and try again.

Can't install from source cause my company proxy replaces the cert file. I also tried:

$ vagrant plugin install vagrant-proxyconf --plugin-source http://rubygems.org/
Installing the 'vagrant-proxyconf' plugin. This can take a few minutes...
Bundler, the underlying system Vagrant uses to install plugins,
reported an error. The error is shown below. These errors are usually
caused by misconfigured plugin installations or transient network
issues. The error from Bundler is:

Could not verify the SSL certificate for https://gems.hashicorp.com/.
There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit.ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.

Warning: this Gemfile contains multiple primary sources. Using `source` more than once without a block is a security risk, and may result in installing unexpected gems. To resolve this warning, use a block to indicate which gems should come from the secondary source. To upgrade this warning to an error, run `bundle config disable_multisource true`.Warning: this Gemfile contains multiple primary sources. Using `source` more than once without a block is a security risk, and may result in installing unexpected gems. To resolve this warning, use a block to indicate which gems should come from the secondary source. To upgrade this warning to an error, run `bundle config disable_multisource true`.Retrying fetcher due to error (2/4): Bundler::Fetcher::CertificateFailureError Could not verify the SSL certificate for https://gems.hashicorp.com/.
There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit.ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.Retrying fetcher due to error (3/4): Bundler::Fetcher::CertificateFailureError Could not verify the SSL certificate for https://gems.hashicorp.com/.
There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit.ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.Retrying fetcher due to error (4/4): Bundler::Fetcher::CertificateFailureError Could not verify the SSL certificate for https://gems.hashicorp.com/.
There is a chance you are experiencing a man-in-the-middle attack, but most likely your system doesn't have the CA certificates needed for verification. For information about OpenSSL certificates, see http://bit.ly/ruby-ssl. To connect without using SSL, edit your Gemfile sources and change 'https' to 'http'.

[kenorb]

Related: mitchellh/vagrant/issues/7787

[codylane]

Closing issue, as the issue is related to user's environment and attempting to install the plugin in a non-standard way.