Jira Service Desk: Jira Service Desk をイントラネット上で管理する
Can I manage JIRA applications on Intranet?
All JIRA applications are web-based applications accessed through a browser, but doesn't necessarily have to be through an Internet connection. As long as your computer with JIRA access is connected to the host server, you should be able to run smoothly with no problems. For example, an intranet, or a LAN network.
This means you can run JIRA without an internet connection, and keep your JIRA instance entirely behind your firewall.
You can download updates from a computer with Internet, and transfer that application to your intranet through a thumb drive, or some other means of transferring data to an intranet from an external source.