# Description Correct ownership, endpoint validation, policy propagation, subscription delivery, file handling and generated-model behavior across the stack, tools and samples. Add focused regression tests and update the corresponding guides and sample documentation. ### Previously included corrections - Require an active, matching session to generate or access transient ResultTransfer file handles. Cover both sessionless generation and reads against a handle owned by an active session, using live session owners in the Machinery tests. - Keep physical filesystem operations within their configured mount and apply the same confinement checks throughout file operations. - Validate LDS semaphore paths consistently during server registration and registration-store maintenance. ### Individual issues addressed | # | Component | Issue and correction | |---|---|---| | 1 | AI jobs and transfers | Jobs and transfers did not consistently retain their creator's identity and session. Apply ownership checks to descendants, file handles, subscriptions and execution, and recheck deployment permissions before dispatch. | | 2 | Password-management client | Password-bearing calls could use signing-only channels or follow a replacement connection. Capture an encrypted transport generation and keep dispatch bound to it; preserve ordinary non-password edits. | | 3 | GDS and certificate-push clients | Connections omitted hostname verification. Validate the original configured DNS name or IP address before session activation. | | 4 | Certificate push | Private-key uploads could use signing-only calls. Require an encrypted, generation-bound dispatch while preserving certificate-only updates and restoring the caller's identity afterward. | | 5 | MQTT client | The .NET Framework custom-trust callback could discard TLS hostname, certificate-availability and usage errors. Retain those checks while supporting configured issuer trust. | | 6 | DTLS handshake | Certificate trust was not tied to the configured peer address. Match the certificate's DNS or IP identity to the intended endpoint. | | 7 | Replicated address spaces | Serialized nodes lost per-node and descendant permission metadata. Preserve role permissions, user-role permissions and access restrictions, including updates to existing replica nodes. | | 8 | MCP PubSub imports | Imports without groups skipped checks on the effective broker destination. Check the actual endpoint before resolving credentials or activating the connection. | | 9 | Reference-server accounts | A disabled username account could authenticate again with its previous roles. Reject disabled accounts during fresh authentication. | | 10 | Console reference client | The sample disabled hostname checks when connecting to an otherwise trusted peer. Retain the original requested host and validate it before activation. | | 11 | Capture replay and export | Replay and raw export could accept non-capture files or include key material. Require complete PCAP/PCAPNG containers and exclude key sidecars and decryption-secret blocks. | | 12 | PubSub adapter fallback | The fallback client configuration automatically accepted peer certificates. Apply normal trust and hostname validation before activation or reads. | | 13 | Kafka transport | Explicit TLS enablement was checked but did not reach both final Confluent configurations. Use the same effective protocol for validation, producers and consumers. | | 14 | PubSub actions | Configuration rebuilds could widen a connection-local action handler's scope. Preserve its original connection association and reject mismatched dispatch. | | 15 | PubSub readers | Reader-level message-protection settings were accepted but ignored. Apply the effective group and reader settings before accepting and publishing received values. | | 16 | PubSub key groups | Different `SecurityGroupId` values could share one connection-wide key context. Reject mixed groups on a connection and require separate connections for distinct groups. | | 17 | MCP session registrations | Session-name replacement or reuse could retain another registration's credential bindings. Bind access to the registration, caller and authenticated endpoint, and preserve that identity when borrowing sessions. | | 18 | Viewer HTTP host | Requests reached the viewer's OPC UA session without consistent Host, Origin and port checks. Validate the request destination and browser origin before using the session, while retaining supported local MCP clients. | | 19 | Vision file operations | File operations did not consistently apply protected-file checks, and remote handles lacked caller and connection context. Apply the shared checks and use host-side opaque handles bound to caller, target and generation. | | 20 | DTLS record integrity | The integrity-only MAC used a truncated sequence number. Authenticate the full reconstructed sequence number and epoch so records remain distinct across rollover. | | 21 | AMB client sample | Connection setup omitted hostname validation. Preserve the originally requested host and verify the peer identity before activation. | | 22 | Robot sample writes | The R2 `SpeedOverride` callback could target R1 state. Bind each callback to its own robot and apply that robot's write policy. | | 23 | AI result properties | Optional result children inherited remotely writable defaults. Preserve their declaration restrictions and keep server-produced results read-only. | | 24 | WSS peer-trust updates | Existing channels did not consistently respond to peer-trust changes. Revalidate complete chains for forward and reverse WSS channels and close only those that no longer validate. | | 25 | GDS revocation checks | Caller-provided certificates could cause issuer retrieval from embedded URLs. Resolve validation from configured local trust, issuers and CRLs without fetching caller-provided locations. | | 26 | GMS observations | Published correction observations retained writable model defaults. Reject remote writes while preserving publisher-side updates. | | 27 | Production-dataset monitoring | Subscription admission and delivery could use the reporter's context instead of each subscriber's permissions. Evaluate the subscriber at admission and on every delivery, including cancellation and disposal paths. | | 28 | WoT MQTT destinations | Hostless MQTT forms could imply a localhost destination before loopback checks. Reject them before credential lookup or connection attempts and validate the effective endpoint. | | 29 | XRegistry opaque reads | Content-ID reads and notifications did not consistently honor encrypted-read requirements or the currently accepted transport. Recheck the bound endpoint and reject transport downgrades before rebinding, including when protected values are already queued. | | 30 | PubSub capture dissection | Key loading did not consistently check the configured capture-root boundary. Check each actual key path immediately before opening it. | | 31 | PubSub publication queues | Imported WriterGroup queues were not fully checked against publish-topic grants. Check the destination actually used by each group. | | 32 | MCP PubSub mutations | A caller-supplied mode could select subscribe grants for an operation that publishes. Derive the required direction and parent context from the actual mutation. | | 33 | Generated write masks | Model import and generation could widen an explicit `UserWriteMask`. Preserve it through import, copy, merge, inheritance and dependency metadata. | | 34 | Generated method flags | An explicit `UserExecutable=false` could be lost. Preserve its specified state and resulting method behavior through the same model paths. | | 35 | Generated role identifiers | Unresolved role identifiers could cause permission entries to be omitted. Preserve namespace-qualified role IDs and report a diagnostic when a policy cannot be represented. | | 36 | Aggregation-server defaults | The `localhost` default did not reliably constrain listener binding. Use numeric loopback for the default endpoint and command-line fallback. | | 37 | Certificate-validation cache | Cached results could skip current leaf or issuer validity checks. Recheck validity windows on cache hits and keep hostname validation independent of cached chain trust. | | 38 | Software-update folders | Revision names and marker contents containing dot segments could select paths outside the software root. Normalize and check every derived path against that root. | | 39 | USDA arrays | Array elements were not encoded for their string or asset context. Escape them as data and preserve valid composition and round-trip behavior. | | 40 | Adapter hot reload | A changed dataset definition with the same name could keep old fields, subscriptions or cached values active. Compare complete immutable definitions and retire old state before replacement. | | 41 | Adapter index ranges | Subscription publication could ignore `IndexRange` and return the complete value. Preserve the requested projection and its status and timestamps; reject unsupported range providers. | | 42 | PubSub metadata and targets | Metadata from one connection could change another connection's target mapping. Scope metadata to its connection and provenance, and resolve targets using actual typed field IDs rather than field names or unintended positional fallback. | | 43 | Scales product locks | Product locks were not applied across every remote mutation path. Apply them consistently to value writes, filling calculations and related recipe/controller operations while retaining permitted updates. | | 44 | Event permission caching | Cached event decisions could outlive identity, role or node-policy changes. Revalidate the current subscriber, event type and source permissions instead of reusing a stale decision. | | 45 | WoT Modbus destinations | Hostless Modbus forms could imply localhost before loopback checks. Reject them before connecting and validate the effective endpoint. | | 46 | MCP local PKI tools | Peer-trust mutations did not consistently require the caller's `CertificateAdministration` grant. Check the capability before trust and untrust operations. | | 47 | Robot-control HTTP bridge | The bridge lacked consistent Host, Origin and port validation and caller-specific session grants. Apply those checks before borrowing the OPC UA session and retain supported local clients. | | 48 | Subscription transfers | Transferred subscriptions could retain cached notifications after the destination's permissions changed. Require authorization continuity between source and destination identities and roles, invalidate stale retransmission data when continuity fails, and preserve retransmission behavior for compatible transfers. | ### Compatibility notes - Replication uses the versioned NSRP v1 policy envelope. Upgrade peers together and re-encode or reseed legacy topology from the authoritative model; missing permission metadata is not inferred from old records. - Integrity-only DTLS peers must be upgraded together for the full sequence/epoch MAC. AEAD behavior is unchanged. - Distinct PubSub key groups require separate connections. - Custom sessions that cannot capture the actual encrypted transport, and subscription providers that cannot honor a requested range, are rejected rather than silently changing the requested behavior. - Subscription transfers retain retransmission data only when the destination authorization remains compatible with the source snapshot; otherwise the old sequence numbers and cached data are invalidated. ## Related Issues No separate tracking issue is linked. The individual corrections are listed above. ## Checklist _Put an `x` in the boxes that apply. You can complete these step by step after opening the PR._ - [ ] I have signed the [CLA](https://opcfoundation.org/license/cla/ContributorLicenseAgreementv1.0.pdf) and read the [CONTRIBUTING](https://github.com/OPCFoundation/UA-.NETStandard/blob/master/CONTRIBUTING.md) doc. - [x] I have added tests that prove my fix is effective or that my feature works and increased code coverage. - [ ] I have added all necessary documentation. - [x] I have verified that my changes do not introduce (new) build or analyzer warnings. - [ ] I ran **all** tests locally using the **UA.slnx** solution against at least .net **framework** and .net **10**, and all passed. - [ ] I fixed **all** failing and flaky tests in the CI pipelines and **all** CodeQL warnings. - [ ] I have addressed **all** PR feedback received.
OPC Foundation UA .NET Standard Reference Server
Additional samples
- MachineTool and wireless peripherals — independently selected machine/peripheral models, per-instance simulation, typed clients, jobs/files, measurements and record/configuration workflows.
- GMS — native systems, environmental warnings and result/characteristic workflows with explicitly simulated providers.
- AutoID — a simulated OPC 30010 RFID reader: synchronous and asynchronous scans, tag memory access and presence events.
- Cranes and Hoists — observed crane topology and authorized simulated limit requests, never physical motion commands.
- Combined companion suite — MachineTool, WMTP, GMS, CranesHoists and MachineVision on one DI/Machinery owner.
- OPC 10000-21 onboarding registrar/client — loads the generated Onboarding companion model, binds the standard registrar administration methods to an injected ticket store, and drives a secure register/unregister round trip with a PowerShell script.
Introduction
This document is referring to the CTT version 1.04.9.398.
This OPC Server is designed to be the default OPC UA Server when opening the OPC UA Compliance Test Tool and it uses an address-space that matches the design of the UACTT and the requirements for OPC UA compliance testing.
It uses the OPC Foundation UA .NET Standard Library. Therefore it supports both the opc.tcp and https transports. There is a .NET framework based server with UI and a .NET Core console version of the server which runs on any OS supporting .NET 8.0 and later.
How to build and run the Windows OPC UA Reference Server with UACTT
- Open the solution UA.slnx with Visual Studio 2026.
- Choose the project
Reference Serverin the Solution Explorer and set it with a right click asStartup Project. - Hit
F5to build and execute the sample.
How to build and run the console OPC UA Reference Server on Windows, Linux and iOS
This section describes how to run the ConsoleReferenceServer.
Please follow instructions in this article to setup the dotnet command line environment for your platform.
Start the server
- Open a command prompt.
- Navigate to the folder samples/Reference/ConsoleReferenceServer.
- To run the server sample type
dotnet run --project ConsoleReferenceServer.csproj. The server is now running and waiting for the connection of the UACTT.
UACTT test certificates
The reference server always rejects new client certificates and requires that the UACTT certificates are in appropriate folders.
- The console server certificates are stored in %LocalApplicationData%/OPC Foundation/pki.
- The Windows .NET framework server stores the certificates in %CommonApplicationData%\OPC Foundation\pki.
- %CommonApplicationData% maps to the path set by the environment variable ProgramData on Windows.
- %LocalApplicationData% maps to a hidden location in the user home folder and depends on the target platform. See Certificates for more information.
Certificate stores
Under pki, the following stores contain certificates under certs, CRLs under crl or private keys under private.
- own contains the reference server public certificate and private key.
- rejected contains the rejected client certificates. To trust a client certificate, copy the rejected certificate to the trusted/certs folder.
- trusted contains trusted client and CAs certificates and CRLs.
- issuer contains CAs certificates and CRLs needed for validation.
- trustedUser contains trusted user and user CA certificates and CRLs.
- issuerUser contains user CA certificates and CRLs needed for validation of the certificate chains.
Placing the UACTT certificates
CTT creates a PKI folder in a new project. There is a subfolder copyToServer which contains the application and user identity certificates. Copy the ApplicationInstance_PKI certificates for testing with the UACTT to the following stores:
- trusted/certs: trusted certificates
- trusted/crl: revocation lists of trusted certificates
- issuer/certs: issuer certificates
- issuer/crl: revocation lists of issuer certificates
Copy the X509UserIdentity_PKI certificates for testing with the UACTT to the following stores:
- trustedUser/certs: trusted user certificates
- trustedUser/crl: revocation lists of trusted user certificates
- issuerUser/certs: user issuer certificates
- issuerUser/crl: revocation lists of user issuer certificates
UACTT Testing
Download and install the OPC UA Compliance Test Tool.
Note: Access to the UACTT is granted to OPC Foundation Corporate Members.
UACTT sample configuration
A sample configuration for the UACTT Version 1.04.9.398 can be found in UAReferenceServer.ctt.xml. Originally the reference server was certified only against the Standard UA Server profile, the Method Server Facet and the DataAccess Server Facet, in addition to all security related profiles. During release testing all Conformance Units should be enabled / checked.
Enabling Alarms & Conditions
The address space for Alarms contains a Start method which needs to be called to produce alarms for CTT testing. The method is called from a connected client.
The ConsoleReferenceServer has also a command line option -ctt which starts the Alarms when the server is started. The following Alarm instances are available for monitoring:
AlarmConditionTypeDiscrepancyAlarmTypeLimitAlarmTypeExclusiveLimitAlarmTypeExclusiveDeviationAlarmTypeExclusiveRateOfChangeAlarmTypeNonExclusiveLimitAlarmTypeNonExclusiveDeviationAlarmTypeNonExclusiveRateOfChangeAlarmTypeDiscreteAlarmTypeSystemOffNormalAlarmTypeExclusiveLevelAlarmTypeNonExclusiveLevelAlarmTypeOffNormalAlarmType
Known missing Tests and Issues
Depending on the setup in the provided project configuration, unsupported profiles should be skipped. At the time of writing (1.4.368) the following tests, profiles or facets are not yet covered or not configured due to issues:
- no support for events, historian and only a few basic Alarms & Conditions.
- Decimal type causes crash of CTT (needs investigation)
- no Image / Enumeration scalar test cases
- Arrays may not include Variant (needs investigation)
- no ArrayItemType implemented
- multiple hierarchical references test node missing
- deprecated security profiles support for SHA1/1k RSA keys implemented not according to certification. SHA1/1k keys can only be turned on/off for all profiles, not just for the deprecated profiles.
- Monitored Items with array are failing a few test cases.
It is recommended to run the server as retail build with disabled logging, to avoid side effects due to timing artifacts when log entries are written to a disk drive.
Running the CTT against a Docker container
Please refer to the Docker container of the Reference Server documentation page. Once setup to map the certificate store and the configuration to a local folder, follow the instructions above to copy the certificates to the PKI and get started.
Finding the Address Space Configuration Code
- Project: Reference Server
- File: ReferenceNodeManager.cs
- Method: CreateAddressSpace
Finding the UA Services
- Project: Opc.Ua.Server
- File: StandardServer.cs