Embedded-device security · FID
Your device connects securely. Does it fail securely, too?
Using TLS is only part of the question. Test whether the device rejects an invalid server certificate before it sends application data, then repeat the procedure after a firmware change.
For embedded-product security teams, device manufacturers, and independent testing labs.
The situation
Your device initiates encrypted connections, but configuring a conventional proxy on it is inconvenient or unavailable. You need to test the client as it operates, not just scan the server or inspect a certificate file.
A practical workflow
Verify a valid connection first
Place FID in an authorized test link and exercise the device against its normal, valid server. Confirm that the intended transaction works and identify the hostname and connection you want to test.
Exercise invalid certificates
Select a target and a supported invalid-certificate case. Trigger a full, certificate-based TLS handshake and verify the intended test certificate was presented. Session resumption can omit certificate exchange; a new connection alone does not prove validation was exercised.
Review evidence, then rerun
Record the certificate identifier, handshake evidence, connection outcome, and any application-data evidence for each case. Preserve the device firmware and configuration, restore the valid baseline, and repeat after a fix.
What to record
Distinguish an explicit certificate rejection from a timeout, a failed connection for another reason, or a case the device never exercised. No observed application data is not, by itself, proof of correct certificate validation. Mark cases that were never exercised as Not run, and unexplained outcomes as Inconclusive.
Example test plan, not measured results
Use these checks to plan a demonstration or evaluation. The observations are yours to collect; this is not a customer case study or a qualification report.
| Check | Observation to record |
|---|---|
| Valid-server control | The intended transaction succeeds before and after the test. |
| Self-signed certificate | Whether the client rejects it or proceeds with application data. |
| Wrong-hostname or expired certificate | The exercised case, connection outcome, and supporting evidence. |
What you need
- A FID configuration with the certificate-validation workflow and compatible tool image; confirm the supplied release and scope in the quotation.
- An Ethernet-connected client, a reachable test destination, and a repeatable way to trigger the relevant TLS connections.
- A separate management connection. The 10 GbE Ubuntu appliance uses a third wired interface; WiFi management applies only to WiFi-enabled platforms.
Before you plan the test
- This tests client certificate validation. It is not a claim to decrypt arbitrary traffic or defeat correctly enforced certificate pinning.
- Protocol, TLS behavior, target selection, and test-case coverage must be checked against the specific device. Results require engineering interpretation.
- FID can operate independently. Optional EtherShunt bypass is available only on 1 GbE links and is not hitless; 10 GbE FID does not inherit that bypass capability.
Discuss your test setup
Start with a non-sensitive description of the setup and the behavior you need to test. Do not submit classified, controlled, or confidential protocol material through this form.
Explore another application
Insert and bypass a test tool
Switch between a direct connection and your inline test equipment. Keep the bench wired as the experiment changes.
Systems integration and verificationTest proprietary protocol behavior
Keep real peers in the test loop while you develop selected message changes and repeatable checks.