Skip to main content
ドキュメントへの更新が� �繁に発行されており、このページの翻訳はま� 行われている� �合があります。最新情� �については、英語版のドキュメントをご覧く� さい。
� 

� 

このバージョンの GitHub Enterprise はこの日付をもって終了となりました: 2022-10-12. 重大なセキュリティの問題に対してであっても、パッチリリースは作成されません。 パフォーマンスの向上、セキュリティの向上、新機能の向上を図るために、最新バージョンの GitHub Enterprise にアップグレードします。 アップグレードに関するヘルプについては、GitHub Enterprise サポートにお問い合わせく� さい。

Troubleshooting SAML authentication

この記事では、次の� �目が扱われます。

If you use SAML single sign-on (SSO) and people are unable to authenticate to access your GitHub Enterprise Server instance, you can troubleshoot the problem.

About problems with SAML authentication

GitHub Enterprise Server logs error messages for failed SAML authentication in the authentication log at /var/log/github/auth.log. You can review responses in this log file, and you can also configure more verbose logging.

For more information about SAML response requirements, see "SAML configuration reference."

Configuring SAML debugging

You can configure GitHub Enterprise Server to write verbose debug logs to /var/log/github/auth.log for every SAML authentication attempt. You may be able to troubleshoot failed authentication attempts with this extra output.

Warnings:

  • Only enable SAML debugging temporarily, and disable debugging immediately after you finish troubleshooting. If you leave debugging enabled, the size of your log may increase much faster than usual, which can negatively impact the performance of GitHub Enterprise Server.
  • Test new authentication settings for your GitHub Enterprise Server instance in a staging environment before you apply the settings in your production environment. For more information, see "Setting up a staging instance."

  1. GitHub Enterprise Server の右上で、ご自分のプロファイル写真をクリックしてから、 [Enterprise 設定] をクリックします。 GitHub Enterprise Server のプロファイル写真のドロップダウン メニューの [自分の Enterprise]

  2. Enterprise サイドバーで、 [ポリシー] をクリックします。 [Enterprise アカウント] サイドバーの [ポリシー] タブ

  3. [ポリシー] で、 [オプション] をクリックします。 [Enterprise アカウント設定] サイドバーの [オプション] タブ

  4. Under "SAML debugging", select the drop-down and click Enabled.

    Screenshot of drop-down to enable SAML debugging

  5. Attempt to sign into your GitHub Enterprise Server instance through your SAML IdP.

  6. Review the debug output in /var/log/github/auth.log on your GitHub Enterprise Server instance.

  7. When you're done troubleshooting, select the drop-down and click Disabled.

    Screenshot of drop-down to disable SAML debugging

Decoding responses in auth.log

Some output in auth.log may be Base64-encoded. You can access the administrative shell and use the base64 utility on your GitHub Enterprise Server instance to decode these responses. For more information, see "Accessing the administrative shell (SSH)."

$ base64 --decode ENCODED_OUTPUT

Error: "Another user already owns the account"

When a user signs into your GitHub Enterprise Server instance for the first time with SAML authentication, GitHub Enterprise Server creates a user account on the instance and maps the SAML NameID to the account.

When the user signs in again, GitHub Enterprise Server compares the account's NameID mapping to the IdP's response. If the NameID in the IdP's response no longer matches the NameID that GitHub Enterprise Server expects for the user, the sign-in will fail. The user will see the following message.

Another user already owns the account. Please have your administrator check the authentication log.

The message typically indicates that the person's username or email address has changed on the IdP. Ensure that the NameID mapping for the user account on GitHub Enterprise Server matches the user's NameID on your IdP. For more information, see "Updating a user's SAML NameID."

Error: Recipient in SAML response was blank or not valid

If the Recipient does not match the ACS URL for your GitHub Enterprise Server instance, one of the following two error messages will appear in the authentication log when a user attempts to authenticate.

Recipient in the SAML response must not be blank.

Recipient in the SAML response was not valid.

Ensure that you set the value for Recipient on your IdP to the full ACS URL for your GitHub Enterprise Server instance. For example, https://ghe.corp.example.com/saml/consume.

Error: "SAML Response is not signed or has been modified"

If your IdP does not sign the SAML response, or the signature does not match the contents, the following error message will appear in the authentication log.

SAML Response is not signed or has been modified.

Ensure that you configure signed assertions for the GitHub Enterprise Server application on your IdP.

Error: "Audience is invalid" or "No assertion found"

If the IdP's response has a missing or incorrect value for Audience, the following error message will appear in the authentication log.

Audience is invalid. Audience attribute does not match https://<em>YOUR-INSTANCE-URL</em>

Ensure that you set the value for Audience on your IdP to the EntityId for your GitHub Enterprise Server instance, which is the full URL to your instance. For example, https://ghe.corp.example.com.

エラー: "Current time is earlier than NotBefore condition" (現在の時刻は NotBefore 条件より前です)

このエラーは、IdP と GitHub Enterprise Server の間の時間差が大きすぎる� �合に発生することがあります。これはセルフホステッド IdP でよく発生します。

この問題を防ぐには、可能であれば、IdP と同じネットワーク タイ�  プロトコル (NTP) ソースを指すようにアプライアンスを設定することをお勧めします。 このエラーが発生した� �合は、アプライアンスの時刻が NTP サーバーと適切に同期していることを確認します。

IdP の立� �で ADFS を使っている� �合は、GitHub のために ADFS の NotBeforeSkew も 1 分に設定します。 NotBeforeSkew を 0 に設定すると、ミリ秒などの非常に短い時間差でも認証の問題が発生する可能性があります。