DUO 2FA是一種雙重身份驗認解決方案，要求用戶在登入已實施2FA的系統之前，從指定的設備（例如你的移動設備）提供第二個認證資料，即 Duo Push Response 或一次性密碼，以進行身份認證。
請立即登記 2FA! 所有同學及同事必須使用雙重認證登入帳戶。實施日期:
教職員及學生 (請參閱以下標籤項目2. 實施範圍)
免費; 需要自行登記服務 (請參閱以下標籤項目1 : 如何運作)
24 X 7 ; 系統維修時段除外
請於ITSC網上服務台, Get Help > Information Security > General Enquiry > 2FA 提交問題
在一般情況下，我們登入帳戶時，只需要提供用戶名稱及密碼來確認身份。當使用DUO 2FA時，我們需要另外提供DUO Push Response 或一次性密碼來連接帳戶。
詳情請參閱標籤項目6. 用戶指南 > DUO 2FA用戶指南。
成功登記使用DUO 2FA後，在登入任何有關需要DUO 2FA的系統時，均需要提供 (i) Duo Push Response 或 (ii) 由 “Duo Mobile” 應用程式產生的一次性密碼，以登入系統。
|(i) Duo Push Response:
||(ii) One-time Passcode:
|微軟Office 365 服務 (包括中大電郵)||2018年8月||√||√|
|The Staff Superannuation Scheme (1995) Enquiry System||2020年3月27日||√
|PG Admission System*
(GS Platform (Division))
(Relevant updating functions under Employee Self-Service)
|UG Admission System*||2020年6月23日||√||不適用|
注意*: 四個主要管理系統(CUPIS, CUSIS, UG及PG Admission Systems) 必須使用2FA。
你可以透過 Duo 2FA Self-Service User Portal 進行以下設定
每個Duo 2FA保安編碼器定價: HK$100
|透過 Duo 2FA Self-Service User Portal進行自助服務登記及設備註冊||
|透過Duo 2FA Self-Service User Portal獲取及使用Bypass Code
|透過Duo 2FA Self-Service User Portal獲取及使用Rescue Code
(只限於緊急使用，例如你當你同時沒有移動設備及有效的學生證時，用作產生 Bypass Code)
* 由2020年12月1日起，iOS 11及Android 7將會不受支援。
Duo Push及Duo 移動設備產生的密碼於iOS 11及Android 7依然生效，用戶可以繼續使用認證。
|中大電郵及其他微軟Office 365 服務||支援新式驗證包括:
|Windows clients login||
|登記||透過網上登記及出席系統 (需要 CUHK Login)|
|摘錄 (透過CUHK Login)||2FA for Preventing Unauthorized Access for students|
|2FA for Preventing Unauthorized Access for staff|
|2FA for Preventing Unauthorized Access for administrators
(資訊保安政策 Security Policy for Handling Personal Data下主要應用系統之管理員)
|簡介會錄影 (透過CUHK Login)||Video of Briefing Sessions for students (中文)
Video of Briefing Session for staff (英文)
Video of Briefing Session for staff (中文)
Video of Briefing Session for Project Accounts (for staff)
Q1: I have a mobile phone and a tablet, can I enroll both of them to use Duo 2FA?
A1: Yes, you can.
Q2: I received an unexpected Duo Push notification from my Duo Mobile App, what should I do?
A2: The Duo Push notification is a login request from your account, if it is not initiated by you or is unexpected, please tap ‘Deny’ to reject the request.
Q3: Can I use Duo Mobile on Windows Phone?
A3: As the application support for Duo Mobile on Windows Phone ended on 1 Jan 2019, and the app was removed from the Windows Store on 10 Mar 2020, you will not be able to download the app from this date. For users who installed and activated the Duo mobile app before 10 Mar 2020, they will not be affected. Details can be found in Duo knowledge base website.<!– Duo Mobile works with Apple iOS & Google Android devices, Palm, Windows Phone 7, Windows Mobile 8.1 and 10, and J2ME/Symbian. (Ref.: https://duo.com/product/trusted-users/two-factor-authentication/duo-mobile)
You may find the latest version of Duo Mobile in the Microsoft Store. Supported Platforms: This version of Duo Mobile supports Windows Phone 8 and greater. Windows Phone 7 users should refer to legacy app documentation. (Ref.: https://guide.duo.com/windows-phone). –>
Q4: I try to login my PC with Duo Authentication, but it prompts “Invalid Certificate” on my mobile and cannot send a push to my mobile.
A4: Please turn off the wifi on your mobile and automatically switch to use your data service provider for network connection. Then try to login again on your PC, a DUO Push should be sent again to your mobile for approval. The error “Invalid Certificate” is most likely triggered by your Wi-Fi which certification is not trusted by DUO.
Q5: I found the following warning message when I login to Duo Portal, may I know what software it will check? If I skip to update the software, will it block us to login?
A5: Only the browser version will be checked and notify user if their browser is out-of-date. You may skip it first to continue and arrange for update according to your usual practice.
Q6: What should I do if I changed my mobile device?
A6: You need to login the Duo 2FA Self-Service User Portal to register your new mobile and manage (delete) your old mobile.
Q7: What can I do if my enrolled mobile device is malfunction?
A7: You need to generate a bypass code with your CU Link Card via Duo 2FA Self-Service User Portal, then use the bypass code to login the Duo 2FA Self-Service User Portal again, register your new mobile and manage (delete) your old mobile.
Q8: If I forgot to bring my enrolled mobile device, can I skip the 2FA?
A8: You need to generate a bypass code with your CU Link Card via Duo 2FA Self-Service User Portal, then use the bypass code to login the systems.
Q9: Will the Duo Push / SMS use my mobile data?
A9: We only enabled Duo Push and it requires Internet connection, so it will use your mobile data if you are receiving Duo Push while you are connecting with your Internet Service Provider.
Q10: When I tried to login O365, I did not receive any message from the Duo mobile app asking me to approve or deny the login.
A10: Sometimes the Duo push did not prompt in time, you may try to open the Duo Mobile app, ‘pull down’ the screen to force a refresh with server. This should trigger to prompt immediately. Details can be found in Duo knowledge base website.
Q11: After I login the system/application with Duo 2FA, do I need to login with 2FA again if I access the system/application later?
A11: It depends on the system/application settings. Usually, the applications have time-out settings which will request users to re-login again.
Q12: Any information will be collected by Duo mobile app if it is installed on the mobile device?
A12: According to Duo’s Service Privacy Notice (https://duo.com/legal/privacy-notice-services), the information they will collect includes:
Q13: How can I generate bypass code for my account?
A13: You can generate bypass code for your account via the Duo 2FA Self-Service User Portal. Please follow the steps below:
Q14: I would like to know how can I generate bypass code for my Tier account?
A14: You can generate bypass code for your Tier account via the Duo 2FA Self-Service User Portal by login with your tier account’s credentials.
Q15: How can I get the bypass code if I don’t have any computer nearby?
A15: You can visit Duo 2FA Self-Service User Portal with your mobile device to generate the bypass code.
Q16: Do I need to generate a bypass code for each login?
A16: The validity of a bypass code is 20 times within 12 hours. If the bypass code is expired, or you forgot the bypass code, you can generate another new bypass code via the Duo 2FA Self-Service User Portal.
Q17: How can I remove Duo 2FA from my account?
A17: Users cannot remove the Duo 2FA from their account by themselves. If you attempt to delete the account in the Duo Mobile app on your mobile device, this will only remove the account from your Duo Mobile app but you will still be promoted for 2FA when you login those 2FA-integrated applications.
Q18: My android smartphone was bought in mainland China and there was no Google Playstore in it, how can I install the Duo mobile app?
A18: For those Android smartphones which cannot connect to the Google Play Store, user can download the Duo Mobile APK directly from official Duo website (update information can be reference from Duo knowledge base website). *Please do not download and install untrusted APK files into your mobile since they may be altered by hackers for malicious purposes.
Then follow the steps in User Manual > under Section 2.1 (vii) for installation.
Please also note that, since Google Play Services is required in order to receive the Duo Push notification on Android devices, for Android devices without Google Play Services installed, you have to open the Duo Mobile app and “fetch” by swiping down in the mobile app (More details can be reference from above Duo knowledge base website and here).
Q1: I would on leave soon and I would use another SIM card, may I know how i can access VPN with Duo 2FA?
A1: Provided that you are using the same mobile for Duo 2FA currently, no matter you changed a new SIM card or even unable connected to the Internet, you can still establish connection to CUHK VPN as usual with Duo 2FA given.
|Password Format||Behavior after inputted password and clicked OK||Condition applied|
|<Onepass>||“DUO Push” will be triggered||Same mobile as current and able to connect to the Internet|
|<Onepass>,<passcode>||Authentication will be proceeded||Unable to be connected to the Internet|
Q2: What is the ‘comma’ in VPN password field used for?
A2: The ‘comma’ shows in answer of last question, i.e. Part (B) A1, is used to separate your VPN password and 2FA passcode.
Q1: Can I use my Android or iOS native mail client to access my O365 mailbox with Duo 2FA?
A1: Duo only work with mail clients which supports modern authentication. For iOS, both native mail client on iOS 12 or above and Outlook app on iOS 12 or above are supported. For Android, native mail client is NOT supported, you can only use the Outlook app for Android to access your mailbox with Duo 2FA, the User Manual for Setting up Outlook App for Android is available. For more details about the supported clients, it can be found in Duo knowledge base website.
Q2: My native mail client which bundled in my iOS does not prompt for Duo 2FA, what can I do?
A2: For iOS, Duo only supports native mail client in iOS 12 or above, so please check and upgrade your iOS if you are using the lower version. Afterwards, you also need to recreate your email account in order to update the authentication settings in your iOS from basic to modern authentication since Duo can only work with application which support modern authenticatoin. Details can be found in Duo knowledge base website.
Q3: My Office 2016 Outlook application does not prompt for Duo 2FA login, when will it ask me to login with Duo 2FA?
A3: You need to clear the Windows Credential Manager in order to trigger Duo 2FA login, please follow the steps below:
Q4: My Office 2013 Outlook application does not prompt for Duo 2FA login, when will it ask me to login with Duo 2FA?
A4: Please make sure that you have updated the following Registry Key to enable the modern authentication for your Office 2013:
Then, clear the Windows Credential Manager in order to trigger Duo 2FA login, steps can be referred to the answer of about question, Part (C) A3.
Q5: My Outlook 2016 for Mac app on my Mac OS does not prompt for Duo 2FA login, when will it ask for my login again?
A5: You need to clear the Keychain Access in order to trigger Duo 2FA login, please follow the steps below:
Q6: Can Gmail support Modern Authentication?
A6: No, Duo 2FA only works with email clients which support modern authentication. As Gmail doesn’t support it, please use the supported clients that listed at https://www.itsc.cuhk.edu.hk/all-it/information-security/two-factor-authentication-2fa/#tab_6 (O365 Services)
Q7: I cannot login my CUHK account in the Microsoft OneDrive app and Microsoft Teams app on my iPhone. After input the login ID and OnePass password, i can receive the Duo Push notification on my mobile device, but after I approve it, the login page prompts “Unknown error” and cannot continue.
A7: According to Duo, this occur recently for users running iOS 13.6 or older version, users are recommended to upgrade their iOS to the latest version 13.6.1 as this is known to resolve the issue.
Q1: During the Duo installation, is it a mandatory / optional to enable the “Bypass Duo authentication when offline (FailOpen)” if it is installed on servers?
A1: By default, Duo Authentication for Windows Logon will “fail open” and permit the Windows logon to continue if it is unable to contact the Duo service. You can set the fail mode during installation to “fail closed” by deselecting the “Bypass Duo authentication when offline” box during installation. This will deny all login attempts if there is a problem contacting the Duo service.
On server systems, you should consider whether security concerns overrides the need for access. For example, in case under man-in-the-middle / DNS spoofing intercepting traffic to *.duosecurity.com, should the server fall back to single factor authentication?
On the other hand, in case of troubleshooting and you have physical access to the system, the “fail closed” setting can be changed in Safe Mode via registry key HKLM\SOFTWARE\Duo Security\DuoCredProv\FailOpen (Set to 1 to allow “fail open” or 0 to restrict to “fail closed”. Default: Fail open.).
Therefore it depends on factors such as security concerns, service design, requirements on availability, accessibility, etc. it is recommended but not mandatory to use set the fail mode to “fail close” on server systems.
Q2: I installed other 2FA solution on my computer before, can I install Duo 2FA additionally?
A2: Please uninstall other 2FA solution on your system before you install the Duo 2FA solution.
Q3: If my notebook installed Duo 2FA, how can I login it when it is not yet connected to Wifi network?
A3: For desktop PC / notebook, if the setting “Bypass Duo authentication when offline (FailOpen)” is selected during the Duo 2FA installation, you can still login the system without 2FA when the system is offline.
Q4: I installed DUO application on my notebook, but after reboot, I cannot login my original Windows account.
A4: Please make sure to match the Windows login username as below:
Q1: How can I purchase the hardware token? How long do I need to wait for getting the token?
A1: Please follow below steps to place order:
Q2: My office ordered and assigned a hardware token to me, what should I do next? How should I register this token?
A2: You are not required to register the hardware token since ITSC would associate the hardware token to your account at the backend of Duo system in advance. So once you have enrolled to Duo 2FA, you can start to use the token immediately to generate the passcode for 2FA login.
Q3: Can I share the hardware token with my colleagues in my department?
A3: No, each hardware token can only be associated to 1 person.
Q4: How long can the hardware token be used?
A4: According to the hardware specification provided by vendor, the battery life of OTP c100 hardware token is around 3-5 years.
Q5: What should I do if I lost the hardware token?
A5: Please report to ITSC immediately for disabling the hardware token. Meanwhile, you can generate a bypass code via Duo 2FA Self-Service User Portal for temporary use, or you may consider to register your mobile device and install the Duo mobile app on your device if you don’t yet have it. And you can order a new hardware token again if necessary.
Q6: How can I set my hardware token as the default device for 2FA?
A6: Sorry, the hardware token cannot be set as a default device if you have more than 1 device registered under your account, only mobile device can be selected as default device to receive the Duo Push notification.
Q7: I have a hardware token and a mobile device registered, which device should I use to generate the passcode for 2FA?
A7: For inputting the passcode as second factor, it is fine to input any passcode generated from your registered mobile device(s) or hardware token(s) assigned to you.
Q8: My office just bought a hardware token for me, why I still received the email reminder from ITSC about enrolling to Duo 2FA?
A8: .If you are the application administrator of the 4 major Admin Systems (CUPIS, CUSIS, UG and PG Admission Systems), you are mandatory to use 2FA to login these system according to the Security Policy for Handling Personal Data. So, if you had been assigned with a hardware token, but you have not yet enrolled to Duo 2FA, ITSC will remind you to enroll Duo 2FA before the deadline.
Q9: Knowing that ITSC would register the hardware token that assigned to me in advance, and I didn’t registered any other mobile device via the Duo 2FA Self-Service User Portal, will I see my token registered in the portal?
A9: Yes, you can find all the devices registered, including mobile device(s) and hardware token(s), under your account by logging in Duo 2FA Self-Service User Portal. Please also note that, by logging in Duo 2FA Self-Service User Portal, you are enrolled to Duo 2FA immediately if you have not yet enrolled before.
Q10: Can I register my mobile device via Duo 2FA Self-Service Portal even though my department has bought me a hardware token from ITSC?
A10: Yes, you can register your mobile device(s) if necessary.
Q11: Understand that a hardware token cannot be shared with multiple person, but can I use the same hardware token for multiple accounts of mine?
A11: Yes, the same hardware token can be associated to multiple accounts of same person.