Article version: Enterprise Server 2.18

Enabling subdomain isolation

You can set up subdomain isolation to securely separate user-supplied content from other portions of your GitHub Enterprise Server appliance.

In this guide

About subdomain isolation

Subdomain isolation mitigates cross-site scripting and other related vulnerabilities. For more information, see "Cross-site scripting" on Wikipedia. We highly recommend that you enable subdomain isolation on your GitHub Enterprise Server instance.

When subdomain isolation is enabled, GitHub Enterprise Server replaces several paths with subdomains.

Path without subdomain isolation Path with subdomain isolation
http(s)://HOSTNAME/assets/ http(s)://assets.HOSTNAME/
http(s)://HOSTNAME/avatars/ http(s)://avatars.HOSTNAME/
http(s)://HOSTNAME/codeload/ http(s)://codeload.HOSTNAME/
http(s)://HOSTNAME/gist/ http(s)://gist.HOSTNAME/
http(s)://HOSTNAME/media/ http(s)://media.HOSTNAME/
http(s)://HOSTNAME/pages/ http(s)://pages.HOSTNAME/
http(s)://HOSTNAME/raw/ http(s)://raw.HOSTNAME/
http(s)://HOSTNAME/render/ http(s)://render.HOSTNAME/
http(s)://HOSTNAME/reply/ http(s)://reply.HOSTNAME/
http(s)://HOSTNAME/uploads/ http(s)://uploads.HOSTNAME/

Prerequisites

Warning: If subdomain isolation is disabled, we recommend also disabling GitHub Pages on your appliance. There will be no way to isolate user-supplied GitHub Pages content from the rest of your appliance's data. For more information, see "Configuring GitHub Pages on your appliance."

Before you enable subdomain isolation, you must configure your network settings for your new domain.

Enabling subdomain isolation

  1. In the upper-right corner of any page, click .

    Rocketship icon for accessing site admin settings

  2. In the left sidebar, click Management Console.

    Management Console tab in the left sidebar

  3. In the left sidebar, click Hostname.

    Hostname tab in the settings sidebar

  4. Select Subdomain isolation (recommended).

    Checkbox to enable subdomain isolation

  5. Under the left sidebar, click Save settings.

    Save settings button

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