The concept of an Active Directory (AD) bridge has been around for a long time. AD bridges allow non-Windows computers such as Unix, Linux, and Macs to become citizens of your Microsoft authentication realm, or put another way, allow you to use your Active Directory username and password to seamlessly authenticate to your non-Windows machines.
However, the need for security measure beyond just a password has been on the rise. While there are many available options for a second, and sometimes even third, form factor during the authentication process, one of the early types of device is still heavily used today, especially in the federal sector. If you haven’t guessed by now, we are talking about smart cards, and the desire to use these devices in conjunction with your Active Directory bridge.
When using smart cards to authenticate, one requirement is to have a smart card reader connected to the machine where you are working (typically a Windows workstation or Linux desktop). This is fine for laptops and workstations located at a user’s desk, but users of Unix and Linux systems typically rely on a remote client (SSH client) to connect to the machine from which they will work.
A common practice is to simply secure the initial workstation login with a smart card authentication, then leverage the Kerberos ticket that is granted during the initial login to control access and provide the authentication to subsequent machines (or in some cases, perform a username/password authentication to the target *nix system). This works fine, and for many implementations, is often my first recommendation. However, this practice also poses a number of challenges. First, the account on the target *nix host is not fully secured—anyone with direct access to the host could attempt to compromise that account using only a password.
This also causes complications for the user as, rather than having to remember a single pin for access, the user must now remember and manage a separate password for the remote account. Often, admins use dual-accounts (separate admin accounts) or have a range of different ID’s they use for different applications. This practice may result in issues with passing audits due to lack of compliance around accounts on critical infrastructure systems.
PowerBroker Identity Services introduces a new feature in version 8.6, allowing for a remote system running the PowerBroker Identity Services agent along with a new client smart card hook to establish a secure tunnel between the user’s workstation and the target server. The user’s smart card reader can then be connected to the target host via this secure tunnel so that the remote system acts as though the smart card reader has been physically connected directly to the machine itself.
Client shim pulling ssh connection information directly from the user's ssh client, establishing a secure tunnel between the target host and user’s workstation, then prompting for smart card authentication during the login process, as well as any time the target server calls for re-authentication.
The key benefit is that a user may perform smart card authentication with the same user on the same card, a different user on the same card, or different users on different cards to securely authenticate to a remote system—without having to be physically next to the server to insert the smart card.
PowerBroker Identity Services (AD Bridge) is BeyondTrust’s solution to extend Microsoft Active Directory authentication, single sign-on capabilities and Group Policy configuration management to Unix, Linux and Mac systems, to improve efficiency, simplify compliance and reduce risk. For more on how we can simplify Unix and Linux security, contact us today
Paul Harper, Product Manager, BeyondTrust
Paul Harper is product manager for Unix and Linux solutions at BeyondTrust, guiding the product strategy, go-to-market and development for PowerBroker for Unix & Linux, PowerBroker for Sudo and PowerBroker Identity Services. Prior to joining BeyondTrust, Paul was a senior architect at Quest Software/Dell. Paul has more than 20 years of experience in Unix/Linux operations and deployments.