Enabling subdomain isolation

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. After enabling subdomain isolation, attempts to access the previous paths for some user-supplied content, such as http(s)://HOSTNAME/raw/, may return 404 errors.

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/`
`https://HOSTNAME/`	`http(s)://docker.HOSTNAME/`
`https://HOSTNAME/_registry/npm/`	`https://npm.HOSTNAME/`
`https://HOSTNAME/_registry/rubygems/`	`https://rubygems.HOSTNAME/`
`https://HOSTNAME/_registry/maven/`	`https://maven.HOSTNAME/`
`https://HOSTNAME/_registry/nuget/`	`https://nuget.HOSTNAME/`

Prerequisites

警告：如果禁用子网分隔，建议同时在企业上禁用 GitHub Pages。 � 法将用户提供的 GitHub Pages 内容与其余企业数据分隔。有关详细信息，请参阅“为企业配置 GitHub Pages”。

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

Specify a valid domain name as your hostname, instead of an IP address. For more information, see "Configuring a hostname."

警告：初始设置后不要更改 GitHub Enterprise Server 的主机名。更改主机名将会导致意外的行为，甚至包括实例中断。

Set up a wildcard Domain Name System (DNS) record or individual DNS records for the subdomains listed above. We recommend creating an A record for *.HOSTNAME that points to your server's IP address so you don't have to create multiple records for each subdomain.
Get a wildcard Transport Layer Security (TLS) certificate for *.HOSTNAME with a Subject Alternative Name (SAN) for both HOSTNAME and the wildcard domain *.HOSTNAME. For example, if your hostname is github.octoinc.com, get a certificate with the Common Name value set to *.github.octoinc.com and a SAN value set to both github.octoinc.com and *.github.octoinc.com.
Enable TLS on your appliance. For more information, see "Configuring TLS."