Frequently Asked Questions

A data diode typically comes in the form of a device, card kit, or appliance allowing data to move freely from one computer to another in only one direction.  Data diodes provide a physical protocol break to prevent data from being transferred from the receiving computer to the sending computer.

The following link is to NSA’s National Cross Domain Strategy and Management Office’s website.  A brief summary of Raise the Bar can be found on this site. https://www.nsa.gov/Cybersecurity/Partnership/National-Cross-Domain-Strategy-Management-Office/

Some clients just need the data diode to provide the ability to send data from one network to another without any possibility that data can be sent in the opposite direction, providing total isolation of the receiving network.  Other clients need a data diode as part of a Raise the Bar (RTB) compliant cross domain system to separate high threat networks (HTNs) from more sensitive networks.

The NCDSMO performs formal assessments of data diode products and if the product passes the assessment, the NCDSMO lists that data diode on their official data diode baseline list.  Fastback was assessed and added to the official data diode baseline list in August 2022.

Fastback supports many different protocols (or connectors) and all connectors are included in the base kit.  The connector configured on the send side does not have to be the same on the receive sides of the diode (e.g., sender gets data from an S3 bucket and receiver delivers data to an SFTP server).  Furthermore, interfacing with Fastback can be request driven or polling. Currently, Probity’s Fastback data diode includes the following connectors:

· SFTP

· NFS

· S3

· SMTP

· REST

· UDP Streaming

· TCP

· FTPS

Many vendor quotes are hard to navigate with many line items for various options the diode supports.  How do I interpret a Fastback quote? Fastback quotes are simple and straightforward.  Each quote is a single line item with a quantity, unit cost and total cost.  The only time a quote includes multiple lines is when a customer has requested a quote to prepay for additional years of maintenance.

Probity has customers transferring files up to 1TB in size with no lost or out of order packets, but we have not published a maximum file size.

When configuring data flows on Fastback, the customer has the option to enable one of two verification options (CRC32 or MD5 Hash) to ensure that the data delivered on the destination network is identical to the data Fastback picked up from the source network.  If either of these options are enabled, Fastback will check the value on the destination network and deliver it to the appropriate folder in the configuration (e.g., Complete, Error).  Note that the CRC32 is a much more efficient option to verify that the data is correct.  The MD5 Hash by its nature is much more expensive from a performance perspective.

No. Fastback is a data diode card kit, specifically designed to move data from one network to another in a uni-directional flow.  However, Probity has many years of experience with solutions that include custom deep content inspection, integration with third-party filter products (e.g., PuriFile™, Glasswall™), and integration with various anti-virus scanners.

Fastback is designed to work “out of the box” using commercially available commodity components.  At the current time, Fastback has been tested using four () different types of NICs and SFPs. There are no custom hardware components in the kit.  Other data diodes consist of custom or modified components such as the NIC cards or even the operating system.  The Fastback software is the differentiator, providing maximum throughput of approximately 9 Gbp/s on a 10 Gbp/s NIC/SFP+ combination.  Furthermore, all features of Fastback are included in every kit so there is no need to swap out or order additional connectors.

The Fastback Diode Kit comes with:

– 10 Gbps NICs (Qty 2)

– SFP modules (Qty 2)

– Fiber Optic Coupler (1)

– System Installation and Administration Manual

– Fastback Software Install Discs (Qty 2)

– Fastback License Disks (Sender and Receiver)

– Fastback License Reference Sheet

Fastback can be installed and configured in approximately 30 minutes.  This includes the installation of the NIC cards in the host computers, connection of the fiber optic coupler between the two host computers and the execution of test data transfers.

Fastback Kits are delivered with a Rocky 8 installation DVD, a derivative of Red Hat® Linux.  If Fastback is installed on top of the Rocky 8 installation provided in the kit, customers have the option to apply a STIG after the Fastback software is completely installed and configured. Probity has many customers that run Fastback on CentOS 7, Rocky 9, RHEL 8, and other derivatives of Linux.

Fastback will work with virtually any commercial or GOTS cross domain guards.  It is designed to be guard agnostic.

Fastback has been tested with four (4) different 10G NIC cards and the NIC cards included in the kit will be whichever cards are available at the time we build a kit for delivery to a customer.  All NICs provided with the Fastback kit are installed in a PCIe slot of a host computer.

Fastback’s throughput speed is typically over 9 Gbp/s.

Yes. Probity has over 20 years of experience designing, building, implementing, and supporting enterprise cross domain systems for multiple agencies in the IC and DoD.  Our engineers have recently completed building an enterprise cross domain solution using RTB compliant guards for one of our clients.  That system is going through the Assessment and Authorization (A&A) process and is expected to be deployed in the Summer 2023. 

Fastback is currently not available as a prebuilt appliance.  However, we have recently tested Fastback on some small form factor host computers with excellent results.  Please contact us at:

[email protected] for more information or to set up a virtual or in person meeting to discuss this option.

Yes. Currently, Fastback is installed on new or wiped host computers (STIGed CentOS 7.9), but once installed, you can install other applications on the host computers.

Fastback is a Linux based solution.  It is not available to run on a Windows machine.

Extra Fastback fiber optic couplers of various lengths can be purchased with an initial Fastback kit order or you can contact [email protected] to request a quote for additional fiber optic couplers.

Rocky 8.9

It is possible to run multiple diodes on a single pair of host computers (i.e., sender and receiver).  Many commercial servers (e.g., Dell R650, HP DL360) have multiple PCIe slots that would allow you to install multiple diodes, increasing your overall throughput using a single set of hardware.

Fastback has few hardware restrictions.  The main requirement is that the host computers have at least one PCIe, Gen 3 or greater, x8 slot available. RAM should be DDR4 or newer. For basic functionality, plan on at least 8GB RAM for each diode sender and 32GB of RAM for each diode receiver.

Maximum diode speed is related to the amount of RAM available to use for buffering on the receiver machine and the maximum IO capabilities of the receiver machine to move data from memory to another destination, such as a local file system or remote system connected via ethernet.

While it is possible to install Fastback on a VM, you would need to have dedicated NICs for the sending and receiving VM so data can be transferred.  It’s important to first check with your Security team to see if they would authorize the implementation of Fastback on VMs.

Fastback comes with one year of annual maintenance which include phone support to assist with installations, configurations, and troubleshooting.  Annual maintenance also includes periodic updates with new features and bug fixes.  Annual maintenance includes a warranty on all Fastback components including the NICs, SFPs and the Fiber Optic Coupler.  Probity can provide a quote for onsite implementation support if desired.

For e-mail support, please contact [email protected]
You can also call us M-F from 8 AM to 5 PM Eastern Standard Time at 571-536-7223.