How to manually install a plugin in Jenkins

Sometimes in corporate environments, accessing certain things from the internet is blocked by the firewall due to restricted access. In case if you ever come across such a scenario, wherein you are not able to install a plugin in Jenkins due to firewall and/or proxy issue, you always have a workaround to manually install the plugin.

Firstly go to the specific plugin page and download it. For instance, consider the Email-ext plugin page for Jenkins and download it. It will have .hpi extension.

Now go the plugins configuration in Jenkins i.e Manage Jenkins => Manage Plugins => Advanced.
Here you'll see the option to upload the plugin .hpi file

Hope it helps. Cheers!