Free tools Windows power users keep installed
One-click scans. No signup required.
To test NGINX mutual TLS (mTLS), exercise the endpoint with a valid client certificate, no certificate, an untrusted certificate, an invalid or expired certificate, and a trusted certificate carrying an unauthorized identity. In a strict configuration, ssl_client_certificate provides the trusted client CA and ssl_verify_client on rejects clients that do not present a valid certificate during the TLS handshake. Log $ssl_client_verify for every test: SUCCESS proves NGINX verified the certificate, NONE means no certificate arrived, and FAILED:reason means a certificate arrived but verification failed.
What NGINX mutual TLS is actually checking
Ordinary HTTPS authenticates the server to the client. Mutual TLS adds client authentication: the client presents a certificate, and NGINX validates its chain against a configured trust anchor before the request is allowed to proceed.
As an Amazon Associate I earn from qualifying purchases.
Two directives determine whether that check is meaningful:
| Directive or variable | Purpose | Important behavior |
|---|---|---|
ssl_client_certificate |
Loads the CA certificates NGINX trusts for client-certificate verification. | It defines who may issue an acceptable client certificate; it does not, by itself, require a client certificate. |
ssl_verify_client |
Controls client-certificate enforcement. | The default is off. on requires a valid certificate, optional requests one but permits a connection without it, and optional_no_ca accepts a certificate without having NGINX validate it against a local CA. |
$ssl_client_verify |
Reports the verification result. | It is SUCCESS, FAILED:reason, or NONE when no certificate was supplied. |
$ssl_client_s_dn and $ssl_client_i_dn |
Expose the client subject and issuer distinguished names. | Useful for logs and downstream authorization, but an identity string must not be trusted unless the certificate itself has been verified. |
A server certificate in the listen 443 ssl block proves only that NGINX can authenticate itself to clients. It says nothing about whether NGINX is requesting or enforcing client certificates. The decisive settings are the client CA file and the value of ssl_verify_client.
#1 Best Overall
- [Ultra-Lightweight Ear Buds Designed for Small Ears] Each earbud weighs only 3.7g and features a compact, ergonomic in-ear design made especially for small ears. Secure, low-profile, and comfortable for workouts, all-day wear or overnight sleeping.The ultra-slim profile sits flush in your ear with no hard edges poking or rubbing, so you can even sleep on your side without discomfort.
- [Immersive Stereo Sound with TOZO OrigX Technology] TOZO OrigX tuning delivers clear vocals, balanced mids, and natural stereo sound for music, podcasts, and videos.
- [Long Battery Life for Daily Use] Get up to 7 hours of playtime on a single charge, with up to 32 hours total using the charging case—ideal for workdays, commuting, and extended listening sessions.
- [Bluetooth 5.3 & Stable Connection] Bluetooth 5.3 provides fast pairing, stable wireless performance, and reduced dropouts as you move around home or office.
- [Deep Bass with Clear Vocals] High-performance drivers produce punchy bass while keeping vocals clean and detailed for everyday listening.
Start with a known strict configuration
Use a small test server or a dedicated location so that inherited configuration cannot hide the behavior you are trying to measure. This baseline enables strict verification and passes the result to an upstream application for independent inspection.
server {
listen 443 ssl;
server_name mtls.example.test;
ssl_certificate /etc/nginx/tls/server.crt;
ssl_certificate_key /etc/nginx/tls/server.key;
ssl_client_certificate /etc/nginx/tls/client-ca.pem;
ssl_verify_client on;
ssl_verify_depth 2;
location / {
proxy_set_header X-Client-Verify $ssl_client_verify;
proxy_set_header X-Client-Subject $ssl_client_s_dn;
proxy_pass http://app;
}
}ssl_verify_depth 2 limits the certificate-chain depth accepted by this example. Set it to match the actual client PKI, including any intermediate CA. A chain that is valid but deeper than the configured limit will not produce SUCCESS.
Before testing, confirm that the CA file contains the issuing CA certificates in PEM format, that the server certificate matches its private key, and that the test hostname resolves to this server. Record the NGINX and OpenSSL versions. Directive availability and variable behavior are version-qualified in NGINX documentation, so version records are essential when a result changes after an upgrade.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsPrepare test cases that can prove a check was skipped
One successful request is not enough. A proxy can be configured to accept every connection while still appearing healthy to a client that has a certificate. Build a set of identities and deliberately malformed cases:
- Valid client: a certificate and private key issued by the CA in
ssl_client_certificate, within its validity period and within the configured chain depth. - No certificate: a client invocation with no certificate or key options at all.
- Untrusted issuer: a certificate signed by a different CA.
- Invalid certificate: an expired, not-yet-valid, malformed, or otherwise unverifiable certificate.
- Wrong identity: a certificate that chains to the trusted CA but whose subject or other identity is not authorized by the application.
Keep each private key separate and label the resulting requests. The wrong-identity case is especially important: chain validation answers “who issued this certificate?”; application authorization must separately answer “is this particular identity allowed to use this endpoint?”
Run the mTLS test matrix
Run every case against the same hostname and path. The expected result depends on whether the endpoint is strict or optional.
Rank #2
- 【IP68 Waterproof Multifunctinal Smart Watch】Torjalph fitness activity tracker smart watch is IP68 waterproof technology ,you can wear it when swimming,handwashing,it's rain-proof which means that you perform multiple exercise modes outside without worrying about sweat or rain corroding your fitness smart watch,and this watch equipped with a 230 mAh large capacity battery magnetic charging ,and this sports activity tracker watch can be used 5-7 days If fully charged.
- 【Larger 1.83'' Full Screen Watch & Multi-dial Selection】1.83 inch full HD color touch screen smart watch for men / women provides excellent 240*284 resolution image quality ,This Bluetooth smart watch offers a better touch experience and remarkable immersion and ,more than 200 watch faces for you to choose from App"Da Fit ", you can change the dial style according to your mood to wear keeping the world on your wrist
- 【Accurate Activity Tracker Smart Watch 】sports watch activity tracker uses sweat and dust resistant breathable silicone strap, our Fitness Tracker Smart Watch for Android iOS Phones supports 12 sports modes,walking,running,bicycle,swimming,badminton,basketball,football,rope skipping. This bluetooth calls smart watch for men women is lightweight and stylish, bringing more convenient and relaxing sports experience while also providing more protection.
- 【Your 24 Hour Personal Daily Health Monitor】Fitness watch for women men full touch screen IP67 waterproof bluetooth smartwatch for Android iOS Phones with heart rate blood pressure monitor multifunction Andriod smart watch with steps counter sleep monitor sports fitness watch, monitoring blood oxygen saturation allows you to understand your physical condition in real time to track fitness progress ,to know your health status in time.
- 【More Functions Bluetooth Call Smart Watch】This fitness activity smart watch full screen for iPhone and Android phones includes a bunch of new features including:The bluetooth smart watch can hang up the phone, receive and display WhatsAPP /Text /Facebook /Twitter /Messenger reminder.Support sedentary reminder, alarm clock, stopwatch, timer,weather information,music control, remote camera control compatible with Android 5.0 and above or iOS 9.0 and above smartphones.
| Test | Client action | Strict (on) |
Optional (optional) |
What proves the result |
|---|---|---|---|---|
| Valid client | Send a certificate and key issued by the configured CA. | TLS handshake succeeds; request reaches HTTP and $ssl_client_verify is SUCCESS. |
Same successful verification result. | Access log and, if used, the upstream header both show SUCCESS. |
| No certificate | Omit client certificate and key options. | Handshake is rejected before a protected HTTP response. | Handshake and HTTP request can succeed with NONE; policy must deny it. |
No protected content is returned, and the log records the expected state. |
| Untrusted issuer | Send a certificate signed by a different CA. | Handshake is rejected. | The request may reach policy with FAILED:reason; policy must deny it. |
The verification result is not SUCCESS. |
| Expired, not-yet-valid, or malformed | Send the deliberately invalid certificate. | Handshake is rejected. | Policy sees a failed verification result and must deny it. | Only a valid, trusted chain can produce SUCCESS. |
| Wrong identity, trusted chain | Send a validly chained certificate whose subject is not authorized. | NGINX can complete TLS verification; the application or access policy must still reject the identity. | Same requirement after the certificate is verified. | Use the logged subject and an explicit authorization rule, not chain validity alone. |
Run the matrix after every change to a client CA, server certificate, NGINX configuration, NGINX version, or OpenSSL library. A change that affects only one branch can leave ordinary “happy path” testing green while weakening rejection behavior.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Test the positive path with curl
Use curl when you want an end-to-end HTTP result. Supply a CA bundle that lets curl verify the NGINX server certificate, then supply the client certificate and matching private key.
curl --cacert /path/to/server-ca-bundle.pem
--cert /path/to/valid-client.crt
--key /path/to/valid-client.key
https://mtls.example.test/protected- Verify that the hostname in the URL is the same name configured in
server_nameand presented through SNI. - Use the client certificate and key from the valid-client case. If they are in a format curl does not accept directly, convert them to the required PEM or other supported format before testing.
- Capture the HTTP status, response body, and the matching NGINX access-log line.
- Confirm that the log says
SUCCESS. A successful HTTP response without that log value does not prove NGINX performed client verification.
For the no-certificate case, run the same command without --cert and --key. In strict mode, the TLS negotiation should fail rather than return the protected resource. In optional mode, curl may receive an HTTP response; that response is safe only if the authorization layer rejects the logged NONE result.
For the untrusted, expired, and wrong-identity cases, substitute only the client certificate and key. Keep the server CA bundle unchanged so that a client-side server-authentication failure is not confused with NGINX’s client-authentication decision.
Inspect the handshake with openssl s_client
Use openssl s_client when you need to see whether the server requests a certificate and which certificate the client actually sends. A command for the positive case is:
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchPC Slower Than It Used to Be?
A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11openssl s_client
-connect mtls.example.test:443
-servername mtls.example.test
-CAfile /path/to/server-ca-bundle.pem
-cert /path/to/valid-client.crt
-key /path/to/valid-client.key
-state -msgRepeat the command without -cert and -key for the no-certificate test. The exact options required depend on certificate encoding and hostname/SNI. Examine the handshake transcript for the server’s certificate-request behavior, then make an HTTP request over the established session if needed. The transcript is diagnostic; the authoritative application result remains the NGINX access log containing $ssl_client_verify.
Rank #3
- [Low Noise High Fidelity] New bee guitar cord with 22AWG oxygen-free-copper center conductors provides enhanced signal transfer, the PVC insulation material and the high-density stranded copper double shield provide noise rejection for quiet operation
- [Ideal for Choice] New bee 1/4 straight and right angle metal connectors, ensures a secure connection in any instrument, pedal, or amp jack. L shape great fro on stage guitar stands
- [Wide Compatible] Suitable for mixer, power amplifier, microphone, effector, decoder, equalizer, electoronic organ, electric guitar, electric bass and other electronic equipments. Widely used in the installation of smart home, karaoke speaker, professional stage audio, etc
- [Easy Disassemble] Making incidental repairs quick and easy! Very nice, flexible cable
- [Dont Hesite to Order] 24 hours customer services and professional technology team are standing by
A client can be configured to ignore a certificate request, and a TLS library can report a connection that is cryptographically healthy even though no client identity was supplied. Therefore, “the handshake completed” is not an mTLS success criterion. Require both the expected handshake outcome and the expected verification variable.
Instrument logs so a skipped check is visible
Temporarily add a dedicated access-log format containing the verification result, identity fields, fingerprint, and serial number. For example:
log_format mtls_debug '$remote_addr $request '
'verify=$ssl_client_verify '
'subject=$ssl_client_s_dn '
'issuer=$ssl_client_i_dn '
'fingerprint=$ssl_client_fingerprint '
'serial=$ssl_client_serial';
access_log /var/log/nginx/mtls-debug.log mtls_debug;Use a unique request path or a request identifier so that each curl or OpenSSL test can be matched to exactly one log entry. Remove or reduce the diagnostic format after testing if the identity fields are sensitive; access logs can contain personal or organizational identifiers.
Interpret the values literally:
SUCCESSmeans NGINX verified the presented certificate against its configured trust and validation rules.NONEmeans no client certificate arrived. It is not an alternate success state.FAILED:reasonmeans a certificate arrived but verification failed. The reason identifies the failure category, but it never authorizes the request.
The clearest evidence of a skipped check is a protected response paired with a log entry showing NONE. That proves the request reached an authorization path that did not require a client certificate. A response paired with FAILED:reason indicates that a certificate was supplied but the failure was not enforced. In either case, investigate the policy, not only the TLS settings.
Enforce authorization when verification is optional
ssl_verify_client optional is useful when one virtual server serves both certificate-authenticated and unauthenticated paths, or when an application needs to make a deliberate decision. It is not strict mTLS by itself: NGINX requests a certificate but permits a connection with none.
Map the verification result to an allow flag whose only success value is SUCCESS:
Rank #4
- Digital Family Calendar: BSIMB digital calendar wall touch screen puts an end to your chaotic life. Designed for busy families, the digital calendar keeps you organised and in step with your family. Assign different colours and tasks to each family member to make family scheduling easier and more intuitive.
- Easy Setup and Auto-Sync: Plug in, connect to WLAN and auto-syn your electric calendar in minutes. Digital wall calendar compatible with Google calendar, iCloud calendar, Outlook calendar, Cozi calendar and Yahoo calendar. Add events directly on the device or through the ecalendar app. Electronic calendar stays current whether you're at work or traveling—no manual updates needed.
- All-In-One Home Assistant: Smart calendar builds habits and encourage independence with personalised chores. Display daily meal plan to reduce the daily ‘What's for dinner?’ stress. To-do lists keep track of everything you want. Turning chores into valuable achievements with stars and rewards, making life easier and more enjoyable.
- Manage Anytime Anywhere: BSIMB electronic calendar for family stay connected with the powerful ecalendar app. Access and manage your digital wall calendar anytime, anywhere with free features like stars & rewards, photo screensaver, chore charts, meals plans, to-do lists etc. Electronic planner paid features like Magic Import tailor advanced tools for users with special needs.
- Stay in Touch with Loved Ones: Share photos or videos from your phone to electronic wall calendar with app, instantly update your life moment, and keep in touch with your family, especially those who are far away; you can also surprise your smart calendar digital wall by sending him a wish card; it's also great for keeping tech-illiterate elders in touch with the youngsters.
map $ssl_client_verify $mtls_ok {
SUCCESS 1;
default 0;
}
server {
listen 443 ssl;
server_name optional.example.test;
ssl_certificate /etc/nginx/tls/server.crt;
ssl_certificate_key /etc/nginx/tls/server.key;
ssl_client_certificate /etc/nginx/tls/client-ca.pem;
ssl_verify_client optional;
location /protected {
if ($mtls_ok = 0) { return 403; }
proxy_set_header X-Client-Verify $ssl_client_verify;
proxy_set_header X-Client-Subject $ssl_client_s_dn;
proxy_pass http://app;
}
}The important property is the default branch: both NONE and every FAILED:... value are denied. Do not write a rule that checks only whether a subject header is non-empty. A failed or unverified certificate can still expose subject data, and a client can supply misleading identity headers unless NGINX overwrites them.
The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →When a request is forwarded upstream, overwrite any client-supplied headers with values derived from the NGINX variables. The upstream should also enforce the allow flag or an equivalent server-side check; treating a header as proof without checking the corresponding verification result recreates the bypass.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Understand the risk of optional_no_ca
ssl_verify_client optional_no_ca requests a certificate but does not require NGINX to find a trusted local CA for it. This mode is intended for architectures in which another service performs certificate verification. Certificate presence alone is not proof of identity.
| Design choice | Handshake behavior | No certificate | Untrusted certificate | Where authorization must occur | Revocation handling |
|---|---|---|---|---|---|
on |
Every client must present a certificate that NGINX can validate; otherwise the handshake is rejected. | Rejected during TLS. | Rejected during TLS. | NGINX performs chain verification; the application still evaluates identity and permissions. | Can use OCSP with ssl_ocsp. |
optional |
NGINX requests a certificate but allows the connection to continue without one. | Request reaches policy with NONE. |
Request can reach policy with FAILED:reason. |
Explicitly deny every value other than SUCCESS for protected resources. |
Can use OCSP with ssl_ocsp; policy must handle the resulting status. |
optional_no_ca |
A certificate may be presented without local CA validation. | Allowed unless another rule denies it. | Presence does not establish trust. | A designated external verifier must authenticate the certificate before any forwarded identity is trusted. | The external verifier’s revocation policy applies; do not treat NGINX’s presence signal as revocation proof. |
If you use optional_no_ca, document the verifier, the authenticated result it returns, and the protected channel between that verifier and NGINX or the application. Test a forged or self-signed certificate and confirm that the external service rejects it before the identity is accepted.
Test identity authorization, not just certificate chains
A certificate signed by the right CA can still belong to the wrong person, device, tenant, or service. NGINX’s successful chain validation does not automatically enforce your application’s subject, SAN, role, or account mapping.
- Issue or obtain two certificates from the trusted CA: one authorized for the endpoint and one validly chained but unauthorized.
- Send each certificate with the same curl command and record
$ssl_client_verify, subject, issuer, fingerprint, and serial. - Confirm that both certificates can produce
SUCCESSat the TLS layer. - Confirm that only the authorized identity passes the application’s access rule.
- Check that the application rejects a request if the subject is missing from its allowlist, even when the chain is valid.
This test catches a common false positive: operators see a valid certificate and conclude that mTLS authorization is working, while the application has never checked which verified identity is making the request.
Add OCSP when revocation status matters
Chain validation does not by itself tell NGINX whether a certificate has been revoked. Configure ssl_ocsp together with ssl_verify_client on or optional when the deployment requires online certificate-status checking. NGINX also needs DNS resolution for the OCSP responder.
Test at least these responder outcomes:
- Good: the certificate is not reported as revoked, so it can continue through the normal verification and authorization path.
- Revoked: the certificate must be denied according to the site’s policy.
- Unknown: decide explicitly whether the site fails open or fails closed. Do not let an implicit network or resolver error decide the security posture.
Record the configured fail-open or fail-closed behavior and repeat the no-certificate, untrusted, and wrong-identity tests with OCSP enabled. A status check should strengthen the existing policy, not replace the requirement that only SUCCESS reaches protected content.
Troubleshoot an apparent skipped check
The request succeeds without a certificate
First inspect ssl_verify_client in the effective configuration, including inherited http, server, and location blocks. If it is off, NGINX is not enforcing client authentication. If it is optional, a successful handshake is expected; verify that the protected location denies NONE. Then check the log entry. A protected response with NONE identifies an authorization bypass.
The certificate is sent but the request is still denied
Check that the certificate chains to the CA in ssl_client_certificate, that the chain depth is within ssl_verify_depth, that the certificate is currently valid, and that the private key matches the certificate. The log’s FAILED:reason value distinguishes “certificate arrived” from “certificate verified.”
The wrong certificate appears to work
Compare the subject, issuer, fingerprint, and serial in the log. If the result is SUCCESS, NGINX has verified the chain; the remaining defect is identity authorization. If the result is FAILED:reason or NONE, inspect the policy that allowed the request anyway. Also verify that upstream headers are overwritten rather than copied from the client.
OpenSSL shows a request but NGINX logs no certificate
A client can receive a certificate request and still decline to send a certificate. Confirm that the positive test includes both the certificate and matching key, that the SNI hostname selects the intended server block, and that you are reading the access log for the same request. Use the exact hostname and port in both curl and openssl s_client.
Results changed after a reload or upgrade
Run the configuration syntax check before reloading, save the effective configuration and the NGINX/OpenSSL versions, and repeat the complete matrix. A change to an included file, CA bundle, chain depth, directive support, or TLS library can alter one test branch without affecting the others.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Safe operating procedure for mTLS changes
- Back up the current NGINX configuration and certificate/CA file metadata.
- Validate syntax before reload using the normal NGINX configuration-test command for your installation.
- Reload only after the syntax check succeeds.
- Run the valid, no-certificate, untrusted, invalid, and wrong-identity cases.
- Correlate every request with the temporary mTLS access log.
- Verify that protected locations allow only
SUCCESS, while intentionally public locations have a documented exception. - If OCSP is enabled, test Good, Revoked, and Unknown behavior and record the fail-open or fail-closed decision.
- Remove temporary verbose logging when its retention and privacy implications have been reviewed.
- Keep the test results with the NGINX and OpenSSL versions, certificate fingerprints, CA-bundle version, and date of the change.
The practical pass condition is not merely “curl returned 200” or “TLS negotiated.” A strict endpoint must reject clients without a valid certificate during the handshake; an optional endpoint must deny every protected request whose $ssl_client_verify value is not SUCCESS; and every accepted identity must still pass the application’s authorization rule.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
