lmxopcua/docs/security.md

Security

v2 status (2026-05-26). The four security concerns below are unchanged in v2. Paths + project names moved: OtOpcUa.Server/Security/ → OtOpcUa.Security/ (Ldap/, Jwt/, Endpoints/AuthEndpoints.cs), OtOpcUa.Admin is gone (its auth + role-grant pages live in OtOpcUa.AdminUI), and Admin auth policies register from OtOpcUa.Host/Program.cs via AddOtOpcUaAuth (src/Server/ZB.MOM.WW.OtOpcUa.Security/ServiceCollectionExtensions.cs) rather than in a separate Admin process. The Admin UI uses a single Cookie authentication scheme — there is no AddJwtBearer pipeline. The Security:Jwt section configures JwtTokenService, which mints a JWT at the /auth/token endpoint for external consumers (OPC UA clients / automation scripts); the cookie itself stores the ClaimsPrincipal directly. DataProtection keys persist to the shared Config DB (PersistKeysToDbContext<OtOpcUaConfigDbContext>) so cookies survive failover between admin-role nodes.

See docs/plans/2026-05-26-akka-hosting-alignment-design.md §5 for the v2 auth + DataProtection rationale.

OtOpcUa has four independent security concerns. This document covers all four:

1. Transport security — OPC UA secure channel (signing, encryption, X.509 trust).
2. OPC UA authentication — Anonymous / UserName / X.509 session identities; UserName tokens authenticated by LDAP bind.
3. Data-plane authorization — who can write and acknowledge alarms on an OtOpcUa endpoint. ⚠️ Enforced today by two coarse, server-wide LDAP role checks (WriteOperate, AlarmAck) — not by the NodeAcl / PermissionTrie subsystem, which is built and unit-tested but never wired. Read, Browse, HistoryRead and Subscribe carry no authorization check at all. See Data-Plane Authorization.
4. Control-plane authorization — who can view or edit fleet configuration in the Admin UI. Gated by the AdminRole (Viewer / Designer / Administrator) claim resolved from LdapGroupRoleMapping.

Transport security and OPC UA authentication are per-node concerns configured in the Server's bootstrap appsettings.json. Data-plane ACLs and Admin role grants live in the Config DB.

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Transport Security

Overview

The OtOpcUa Server supports configurable OPC UA transport security profiles that control how data is protected on the wire between OPC UA clients and the server.

There are two distinct layers of security in OPC UA:

• Transport security -- secures the communication channel itself using TLS-style certificate exchange, message signing, and encryption. This is what the OpcUa:EnabledSecurityProfiles setting controls.
• UserName token encryption -- protects user credentials (username/password) sent during session activation. The OPC UA stack encrypts UserName tokens using the server's application certificate regardless of the transport security mode. UserName authentication therefore works on None endpoints too — the credentials themselves are always encrypted. A secure transport profile adds protection against message-level tampering and eavesdropping of data payloads.

Supported security profiles

The profiles are the members of the OpcUaSecurityProfile enum (src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OpcUaApplicationHost.cs). The server ships three baseline profiles; the config value is the bare enum-member name (no hyphens, no underscores):

Enum member	Security Policy	Message Security Mode	Description
None	None	None	No signing or encryption. Suitable for development and isolated networks only.
Basic256Sha256Sign	Basic256Sha256	Sign	Messages are signed but not encrypted. Protects against tampering but data is visible on the wire.
Basic256Sha256SignAndEncrypt	Basic256Sha256	SignAndEncrypt	Messages are both signed and encrypted. Full protection against tampering and eavesdropping.

BuildSecurityPolicies (OpcUaApplicationHost.cs) maps each configured profile to an SDK ServerSecurityPolicy. The server exposes a separate endpoint per configured profile and clients select the one they prefer at session open. The enum's XML doc notes that Aes128/Aes256 variants can be added later by extending the enum + BuildSecurityPolicies — the wiring is profile-agnostic — but they are not implemented today. There is no SecurityProfileResolver class.

Config value form. The enum binds by member name, so a profile string with hyphens (e.g. Basic256Sha256-Sign) does not bind — use the exact enum-member spelling above. If EnabledSecurityProfiles is empty, the server falls back to a single None endpoint (logged, very visible) so it still has a listening endpoint.

Configuration

Transport security is configured in the OpcUa section of the Host process's bootstrap appsettings.json (bound to OpcUaApplicationHostOptions):

{
  "OpcUa": {
    "ApplicationName": "OtOpcUa",
    "ApplicationUri": "urn:node-a:OtOpcUa",
    "PublicHostname": "0.0.0.0",
    "OpcUaPort": 4840,
    "PkiStoreRoot": "C:/ProgramData/OtOpcUa/pki",
    "AutoAcceptUntrustedClientCertificates": false,
    "EnabledSecurityProfiles": [ "Basic256Sha256Sign", "Basic256Sha256SignAndEncrypt" ]
  }
}

EnabledSecurityProfiles is a list — the server publishes one endpoint per entry. The default (when the key is omitted) is all three baseline profiles (None, Basic256Sha256Sign, Basic256Sha256SignAndEncrypt); production deployments typically drop None. The list must contain at least one entry (OpcUaApplicationHostOptionsValidator enforces MinCount(…, 1)).

The server certificate is auto-generated on first start if none exists in PkiStoreRoot/own/. Always generated even for None-only deployments because UserName token encryption depends on it.

PKI directory layout

{PkiStoreRoot}/
  own/        Server's own application certificate and private key
  issuer/     CA certificates that issued trusted client certificates
  trusted/    Explicitly trusted client (peer) certificates
  rejected/   Certificates that were presented but not trusted

Certificate trust flow

When a client connects using a secure profile (Sign or SignAndEncrypt), the following trust evaluation occurs:

1. The client presents its application certificate during the secure channel handshake.
2. The server checks whether the certificate exists in the trusted/ store.
3. If found, the connection proceeds.
4. If not found and AutoAcceptUntrustedClientCertificates is true, the certificate is automatically copied to trusted/ and the connection proceeds.
5. If not found and AutoAcceptUntrustedClientCertificates is false, the certificate is copied to rejected/ and the connection is refused.

The Admin UI Certificates.razor page (src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Certificates.razor) lists the contents of each PKI sub-store (own / trusted / issuer / rejected) by reading the OpcUa:PkiStoreRoot path from configuration. FleetAdmin users get per-row actions on the trusted and rejected stores: Trust (move a rejected cert into trusted/), Untrust (move a trusted cert back into rejected/), and Delete (remove a cert from either store). Each action requires an inline confirmation, is re-checked against the FleetAdmin policy server-side, and is honored live — the SDK trust list re-enumerates the directory store on the next handshake, no restart required. (own / issuer remain read-only.) The actions are filesystem moves/deletes performed by CertificateStoreManager, which finds the target by matching the certificate thumbprint — never by building a path from caller input.

Production hardening

• Set AutoAcceptUntrustedClientCertificates = false.
• Drop None from EnabledSecurityProfiles.
• Promote trusted client certs with the Admin UI Certificates page's Trust action (FleetAdmin) — or by moving the .der from rejected/ to trusted/certs/ — rather than relying on the auto-accept fallback.
• Periodically audit the rejected/ directory; an unexpected entry is often a misconfigured client or a probe attempt.

---

OPC UA Authentication

The Server accepts three OPC UA identity-token types:

Token	Handler	Notes
Anonymous	No IOpcUaUserAuthenticator call — the SDK admits anonymous sessions at the channel.	⚠️ An anonymous session carries no roles, so it is refused every write and every alarm ack — but it can Browse, Read, Subscribe and HistoryRead the entire address space. There is no per-node ACL check on those operations (see Data-Plane Authorization). Do not expose an Anonymous-admitting endpoint to an untrusted network.
UserName/Password	ApiKeyOpcUaUserAuthenticator.AuthenticateUserNameAsync (src/Server/ZB.MOM.WW.OtOpcUa.Host/OpcUa/ApiKeyOpcUaUserAuthenticator.cs, implements IOpcUaUserAuthenticator), backed by an IApiKeyStore.	The username is the literal apikey and the password is an otua_<keyId>_<secret> credential (#520). One indexed lookup plus one peppered HMAC-SHA256, no network I/O. The key resolves to a principal, whose NodeAcl grants become roles on a RoleCarryingUserIdentity. LDAP is not on this path — it backs AdminUI login only.
X.509 Certificate	Stack-level acceptance during the secure-channel handshake.	The certificate must be trusted (see PKI trust flow). It carries no roles, so a cert-only session is read-everything / write-nothing.

When no authenticator is supplied, OpcUaApplicationHost falls back to NullOpcUaUserAuthenticator; the Host wires the real ApiKeyOpcUaUserAuthenticator as a singleton in Program.cs. Which IApiKeyStore backs it depends on the node's role:

Node	Store	Revocation takes effect
admin (including fused admin,driver)	ConfigDbApiKeyStore — reads the config database per request	On the next request
driver-only	ArtifactApiKeyStore — reads the keys carried by the deployment artifact, held in memory	On the next deployment
neither role	NullOpcUaUserAuthenticator — denies every UserName token	n/a

The deny-all is registered explicitly, not left absent: OtOpcUaServerHostedService takes IOpcUaUserAuthenticator as a required constructor parameter, so an unregistered seam fails DI and the node does not boot at all.

LDAP bind flow (OtOpcUaLdapAuthService)

LDAP is configured under the Security:Ldap section (bound to LdapOptions, src/Server/ZB.MOM.WW.OtOpcUa.Security/Ldap/LdapOptions.cs, SectionName = "Security:Ldap"). The app authenticator is OtOpcUaLdapAuthService — a thin wrapper around the shared ZB.MOM.WW.Auth.Ldap directory client that adds two app-only concerns the shared library deliberately does not model: the Enabled master switch and DevStubMode. The same ILdapAuthService instance serves both the Admin UI cookie login (/auth/login) and the OPC UA UserName path (via LdapOpcUaUserAuthenticator), so operators use one credential across both planes.

OtOpcUaLdapAuthService.AuthenticateAsync:

1. If Enabled = false, denies outright — no bind, no DevStub bypass (the master switch wins).
2. If DevStubMode = true, accepts any non-empty credentials and grants the Administrator role without any network bind (dev only — must be false in production).
3. Refuses to bind over a plaintext transport (Transport = None) unless AllowInsecure = true (dev/test only). This is enforced at login, not at startup.
4. Delegates the real path to the shared ZB.MOM.WW.Auth.Ldap client: it binds (search-then-bind via ServiceAccountDn, or direct-bind cn={user},{SearchBase} when no service account is set), verifies the password, and reads the user's group memberships.
5. Returns an LdapAuthResult carrying the validated username + the groups (never roles). Failure codes are folded into opaque user-facing error strings so a probe cannot distinguish "unknown user" from "wrong password".

Group → role mapping happens downstream, not in the auth service: LdapOpcUaUserAuthenticator resolves IGroupRoleMapper<string> (OtOpcUaGroupRoleMapper) per call and unions its output with any pre-resolved roles (the DevStub Administrator grant). The roles are attached to the OPC UA session identity (RoleCarryingUserIdentity), where the write and alarm-ack gates read them. The LDAP group names themselves are consumed here and go no further — which is one reason the NodeAcl subsystem cannot currently be wired, since it matches on groups rather than roles. A mapper fault (e.g. a Config DB outage) falls back to the pre-resolved baseline rather than denying an otherwise-authenticated session.

Transport replaces the former UseTls bool: Ldaps (implicit TLS), StartTls (upgrade), or None (plaintext, requires AllowInsecure). Configuration example (Active Directory production):

{
  "Security": {
    "Ldap": {
      "Enabled": true,
      "DevStubMode": false,
      "Server": "dc01.corp.example.com",
      "Port": 636,
      "Transport": "Ldaps",
      "AllowInsecure": false,
      "SearchBase": "DC=corp,DC=example,DC=com",
      "ServiceAccountDn": "CN=OtOpcUaSvc,OU=Service Accounts,DC=corp,DC=example,DC=com",
      "ServiceAccountPassword": "<from your secret store>",
      "GroupAttribute": "memberOf",
      "DisplayNameAttribute": "cn",
      "UserNameAttribute": "sAMAccountName",
      "GroupToRole": {
        "OPCUA-Designers": "Designer",
        "OPCUA-Admins": "Administrator",
        "OPCUA-Operators": "Operator"
      }
    }
  }
}

GroupToRole maps LDAP group names → roles (case-insensitive); a user gets every role whose source group is in their membership. The values are the canonical control-plane role strings (Viewer / Designer / Administrator, plus the appsettings-only Operator for the DriverOperator policy); the same map also supplies data-plane role strings (ReadOnly, WriteOperate, WriteTune, WriteConfigure, AlarmAck) — see Role grant source (data-plane) below. UserNameAttribute: "sAMAccountName" is the critical AD override — the GLAuth dev default is cn, which is not how AD users are looked up; use userPrincipalName instead if operators log in with user@corp.example.com form. LdapOptionsValidator (src/Server/ZB.MOM.WW.OtOpcUa.Host/Configuration/LdapOptionsValidator.cs) fails startup when Transport = None and AllowInsecure = false on a real-LDAP (non-DevStub) config.

API-key identity (OPC UA data plane)

The OPC UA data plane is machine-to-machine, so a consuming system authenticates with an API key rather than an LDAP user (Gitea #520). The client presents an OPC UA UserName token whose username is the fixed literal apikey and whose password is the key:

otua_<keyId>_<secret>

ApiKeyOpcUaUserAuthenticator verifies it — one indexed lookup on keyId plus one peppered HMAC-SHA256 over the secret, compared with CryptographicOperations.FixedTimeEquals. No network I/O. The key resolves to a principal, and NodeAcl rows naming that principal are what grant it permissions.

Key	Notes
Security:ApiKeys:Username	The static username clients present. Default apikey. Checked rather than ignored, so a typo is an explicit denial.
Security:ApiKeys:Pepper	Server-side pepper for the stored hashes. Supply via Security__ApiKeys__Pepper or ${secret:} — never commit it. Rotating it invalidates every existing key. Has no default: an empty pepper still hashes "successfully", so ApiKeySecret.ComputeHash throws on one rather than producing a working-looking deployment with no protection.

Secrets are never stored — only the hash. The plaintext is shown once at creation and is unrecoverable afterwards.

Every rejection returns the same opaque message ("Invalid API key"), with the real reason logged server-side only, so the server cannot be used as an oracle for whether a key id exists or which half of a credential was wrong.

⚠️ Revocation requires a deploy. Per-cluster mesh Phase 4 leaves driver-only nodes with no ConfigDb, so keys reach them inside the deployment artifact exactly as NodeAcl rows do. Clearing Enabled takes effect on a node only once a new artifact reaches it.

Anonymous is a normal principal

Anonymous sessions are admitted by default (OpcUa:AllowAnonymous, default true — flipping the default would silently deny every client that has no key the moment this code deploys, including ScadaBridge). Set it to false to make keys mandatory: the Anonymous token policy is then not advertised, so a client is refused at discovery rather than only at activation, and anonymous activation is rejected independently in case a client attempts a token type the endpoint never offered.

When admitted, an anonymous session is not a special case — it authenticates as the reserved principal anonymous, and NodeAcl rows naming it grant permissions exactly as they would a key's principal. It can therefore be granted write, not merely tolerated as read-only. It arrives at the downstream gates as the same RoleCarryingUserIdentity a key produces, so no gate carries an anonymous-shaped branch and there is no bypass path to get wrong.

Two consequences worth knowing:

• anonymous is reserved: an API key may not use it as its principal, or a credentialled client would silently inherit whatever anonymous was granted. Rejected at authentication as well as at authoring.
• If the anonymous principal's grants cannot be read, the session is denied, not admitted with no roles. Admitting is the pre-#520 behaviour, and defaulting to it precisely when the server cannot determine what anonymous may do stops being harmless once reads are gated.

⚠️ Node ACLs are enforced only when Security:Acl:Enabled is set, and only for three operations. With the flag off — the default — a key's grants are collapsed into the two server-wide role gates and only Cluster-scoped grants count, so a narrower grant confers nothing rather than silently widening to server-wide authority. With it on, writes, alarm commands and HistoryRead are decided by scoped NodeAcl grants; reads, browses and subscriptions stay ungated in either mode (stage 6). See Node ACL enforcement and docs/plans/2026-07-31-apikey-acl-enforcement-design.md.

LDAP resilience — mostly retired with the data-plane authenticator (#520)

Changed 2026-07-31. The OPC UA data plane no longer uses LDAP at all — it authenticates with API keys (see API-key identity). LdapOpcUaUserAuthenticator is deleted, and with it four of the five Security:Ldap resilience keys: AuthTimeoutMs, MaxConcurrentAuthentications, OutageFailureThreshold and OutageCooldownSeconds. Setting them now does nothing (options binding ignores unknown keys); remove them from any config that carries them.

Those four existed for one specific reason. The OPC UA SDK raises its impersonation callback synchronously, inside a SessionManager-wide event lock (verified against OPCFoundation.NetStandard.Opc.Ua.Server 1.5.378), so a slow or hung LDAP bind in that callback did not stall one SDK thread — it serialized every session activation server-wide, Anonymous and X509 included. That constraint is gone: key verification is one indexed lookup plus one HMAC, with no network I/O on the path.

LDAP now runs only on AdminUI login, an ordinary async request path where a slow directory affects the one request making it. One key remains:

Key	Default	Bounds
ConnectionTimeoutMs	10000	Projected into the shared library's ConnectionTimeoutMs — bounds the socket connect and each per-operation search. Validated > 0 at startup by LdapOptionsValidator.

---

Data-Plane Authorization

⚠️ Read this first (updated 2026-08-01, #520 stages 5–6). Whether the NodeAcl / PermissionTrie subsystem runs depends on one flag. With Security:Acl:Enabled false — the default — it does not: the only authorization in the server is the coarse role checks in What is enforced with the flag off, and read, browse, subscribe and HistoryRead are ungated for any admitted session including Anonymous. With it true, those role checks are replaced by scoped ACL decisions and every data-plane operation is gated — see Node ACL enforcement.

What is enforced with the flag off

There are exactly three authorization checks in the whole OPC UA server layer. All three are coarse, server-wide role string checks with no per-node component.

Operation	Gate	Requires
Write (Value attribute, either namespace)	OtOpcUaNodeManager.EvaluateEquipmentWriteGate	role WriteOperate
Alarm Acknowledge / Confirm / AddComment / Shelve / Unshelve (scripted alarms)	OtOpcUaNodeManager.HandleAlarmCommand	role AlarmAck
Alarm acknowledge (driver-fed native alarms)	OtOpcUaNodeManager.HandleNativeAlarmAck	role AlarmAck

Both gates fail closed — a session with no identity or no matching role gets BadUserAccessDenied — and read identity.Roles off the session's RoleCarryingUserIdentity (src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Security/RoleCarryingUserIdentity.cs). Role strings are the constants in OpcUaDataPlaneRoles, sourced from Security:Ldap:GroupToRole (see Role grant source).

What has no authorization check at all:

• Read, Browse, TranslateBrowsePaths — no override, no handler. Any admitted session, including an Anonymous one, sees and reads the entire address space.
• HistoryRead — all four overrides (HistoryReadRawModified, HistoryReadProcessed, HistoryReadAtTime, HistoryReadEvents) run without an identity check.
• CreateMonitoredItems / subscriptions / TransferSubscriptions.
• Non-Value attribute writes — the gate hangs off OnWriteValue.

And what the write gate does not distinguish:

• WriteTune and WriteConfigure are never checked. They exist in the role vocabulary and in NodePermissions, but every write — whatever the tag's security classification — is gated on the single WriteOperate string.
• AlarmAcknowledge / AlarmConfirm / AlarmShelve are not distinguished. One AlarmAck role covers all five alarm methods; the operation argument is passed to the router but never consulted by the gate.
• There is no per-node granularity. A session that may write one tag may write every writable tag on the node.

The gate is realm-aware in one narrow sense: it is attached per-node during materialization for both the Raw and UNS realms, and the write dispatch it guards is realm-qualified. The role decision itself takes no realm and no node.

Node ACL enforcement (Security:Acl:Enabled)

Key	Default	Effect
Security:Acl:Enabled	false	true makes scoped NodeAcl grants decide every data-plane operation — read, browse, subscribe, write, alarm commands and HistoryRead

Live-gated on docker-dev 2026-08-01 (site-a-1 with the flag on, central-1 as the same-artifact control): scoped read/browse/write behave as described below, and revoking a grant stopped a running subscription mid-stream — the client received BadUserAccessDenied, then 25 seconds of silence, then the feed resumed by itself when the grant was restored. Evidence + what the gate did not cover (UNS grants, alarm scoping) in docs/plans/2026-07-31-apikey-acl-enforcement-design.md.

It is a config change, not a redeploy. Both paths are wired in both modes — the node always builds its permission trie on every deploy and always constructs the gate; the flag only chooses which decision the seams consult. Same dark-switch discipline as MeshTransport, ConfigSource and Telemetry.

What changes when it is on

Operation	Off	On
Write (Value)	role WriteOperate	NodePermissions.WriteOperate on that node's scope
Alarm Acknowledge / AddComment / Enable / Disable	role AlarmAck	AlarmAcknowledge on the condition's scope
Alarm Confirm	role AlarmAck	AlarmConfirm
Alarm OneShotShelve / TimedShelve / Unshelve	role AlarmAck	AlarmShelve
HistoryRead (all four variants)	nothing	HistoryRead on each node's scope, decided per node in the batch
Read (every attribute, not just Value)	nothing	Read on that node's scope, decided per node in the batch
Browse / TranslateBrowsePath	nothing	Browse on the source node, and on each returned reference
CreateMonitoredItems / SubscribeToEvents	nothing	Subscribe on that node's scope, decided per item

⚠️ The ACL decision REPLACES the role check; the two are not chained. Chaining them would require a grant to confer the server-wide role as well as pass the scope check, and only Cluster-scoped grants confer a role (ApiKeyInterimRoleMapper) — so every narrow grant would remain inert and the flag would look like it did nothing. Narrow grants working is the whole point of the stage.

Behaviours worth knowing before enabling it:

• A deploy takes effect on sessions that are already open. The gate stamps each decision with the current authority generation rather than the one the session activated under, so an ACL edit lands without bouncing clients — in both directions, widening and narrowing.
• Revocation also reaches an open session. Every decision re-checks the authenticating key against the current snapshot, so a key disabled or expired by a later deployment stops working immediately rather than at the client's next reconnect. On a driver-only node the artifact is the only revocation channel there is, so without this a revoked credential could keep its authority indefinitely.
• Revocation reaches a live subscription too (#520 stage 6). Every other operation re-asks on each request; a subscription is authorized once and then streams, so it needed a push. A deployment re-authorizes every live monitored item: one whose grant has gone is queued a BadUserAccessDenied and then detached from its node's value fan-out, and a later deployment that restores the grant re-attaches it. This matters more than it sounds — subscriptions are how machine consumers actually read this server, so without it revoking a grant would close the operations nobody uses and leave the feed running.
• An ancestor of a granted node is browsable, or no narrow grant would be reachable: a client arrives at a deep node by browsing its ancestors, and the trie otherwise inherits downward only. Note what this necessarily discloses — the names of the folders on the path to a granted node are visible to whoever holds that grant. It is conferred only by grants that actually carry Browse, and it confers nothing but Browse.
• A denied node reports BadUserAccessDenied rather than BadNodeIdUnknown, because the gate runs before node resolution. That is the information-hiding direction — error codes can no longer be used to enumerate the address space — but it does mean "access denied" is not evidence the node exists.
• The two namespace root folders remain visible to any admitted session. They are referenced from the ns=0 Objects folder, whose browse the SDK's own node manager serves; a session with no grants sees the two roots and is refused on entry.

Cost

Read, Browse and subscription creation ask the same question many times per request — one Browse of a device folder asks once per child. Those seams go through a per-(session, node, operation, realm) decision cache, flushed wholesale whenever the authority generation advances.

⚠️ The cache holds the grant walk, not the decision. Grants, principals and the trie are all fixed for the life of a generation, so memoizing the walk is sound. A key's ExpiresUtc passes with the clock, not with a deployment — so revocation and expiry are re-checked on every call, outside the cache. Caching them would have let an expired key keep working until the next deploy.

Everything denies when something is missing

No identity, no principal on the identity, no cluster identity on the node, a NodeId with no string identifier, or a trie that was never installed — each returns BadUserAccessDenied. The client is told nothing beyond that; the reason is logged server-side (AclGate: denied …) so the server cannot be used as an oracle for which nodes exist or which grants a principal holds.

The consequence to plan for: a wiring or configuration mistake presents as everything denied, not everything allowed. Confirm the trie exists at all before debugging a specific rule — the OpcUaPublish: data-plane authority generation N installed line reports the grant count, and a separate warning names every rule the build dropped (a dangling ScopeId, a blank one, a retired scope kind, or a scope path that does not start at a realm). A dropped rule can never match anything.

The NodeAcl + PermissionTrie subsystem

What is real about it:

• Operators can author NodeAcl rows in the Admin UI (/clusters/{id}/acls), and those rows are validated, versioned and persisted.
• ConfigComposer does snapshot every NodeAcl row into every deployment artifact, so an ACL edit shifts the artifact's RevisionHash and ships to every node.
• The node side does deserialize them (#520 stage 4) — DeploymentArtifact.ParseDataPlaneAuthority reads the artifact's NodeAcls (scoped to the node's own cluster) and ApiKeys, and OpcUaPublishActor installs both on the node's IDataPlaneAuthoritySource on every apply. The node manager holds that source, so it has a cluster identity.
• The same Apply call builds and installs the permission trie (#520 stage 5), under the same generation as the snapshot. Deliberately one call rather than two wirings: an uninstalled trie denies everything, which is indistinguishable from working enforcement until someone checks that an ALLOW is possible at all.
• DataPlaneAuthorizer evaluates them at every data-plane seam (#520 stages 5–6), when the flag is on. With the flag off an operator can still author a grant, deploy it green, and have it change nothing beyond the two coarse role gates — that is the documented default, not an unfinished state.

The four things blocking a wire-up (all verified, none of them merely "call the evaluator"):

1. Raw-realm nodes have no representable scope. Closed by #520 stage 3. NodeScope is now (ClusterId, Kind, Segments) with a variable-length path, and NodeHierarchyKind carries both Uns and Raw. The previous fixed-arity shape could not address a real raw tree at all — folder chains and tag-group chains both nest without bound — so it silently capped at five levels and mislabelled every one of them. Four Raw* scope kinds were appended for authoring.
2. The identity carries roles, not groups. Dissolved by #520 stage 2. The column is now NodeAcl.Principal and the principal comes from the presented API key (or the reserved anonymous), not from a directory — so there is no group list to lose.
3. PermissionTrieBuilder's scopePaths argument has no producer. Closed by #520 stage 3. AclScopePathResolver is that producer, built on both sides of the split — EF entities at the deploy gate, artifact JSON on the node — and scopePaths is now a required argument with no fallback: an unresolvable scope is dropped with a diagnostic rather than planted at a trie position the walk can never reach. A scope resolves to several paths when one entity is reachable at several NodeIds (a raw tag projected into N equipments has one raw path plus N UNS paths), because a grant that covered only some of them would be bypassable through the one it missed.
4. No session lifecycle exists. Closed by #520 stage 5, though not as the blocker imagined. The generation exists and advances (stage 4), and DataPlaneAuthorizer now builds a UserAuthorizationState stamped with it — but per authorization call, not per session. The per-session design was LDAP-shaped: it assumed a directory could change a session's group membership out of band, so a long-lived session had to re-resolve on a timer and serve cached memberships in between. Under API keys nothing can change out of band — the principal comes from the key, and keys and grants both ride the deployment artifact — so the generation stamp is the entire invalidation signal, and rebuilding a small record per call picks it up for free while a cached one would have to be explicitly invalidated. The consequence is that UserAuthorizationState.IsStale and NeedsRefresh can never fire on this path; they are vestigial here rather than load-bearing. Caching becomes necessary at stage 6's read/browse/subscribe seams, which are on the publish path — and it will want a per-(session, node) decision cache, not this type.

NodeAclScopeKind.FolderSegment is the retired v2 kind with no v3 entity behind it. It is still offered in the authoring dropdown (labelled retired), but it can never resolve, and both ends now say so specifically rather than reporting it as a missing id: the deploy gate rejects it with NodeAclScopeKindRetired, and the trie builder drops it with a RetiredScopeKind diagnostic (Gitea #533 — it used to arrive as UnresolvedScope, which sent an operator holding a legacy row hunting for a typo in an id that was never the problem). One inconsistency remains: NodePermissions.AlarmRead has no OpcUaOperation mapping, so it is grantable but unreachable.

String identity in this subsystem (Gitea #533): identifiers — ScopeId, ClusterId, Principal — compare OrdinalIgnoreCase, because they are opaque handles whose spelling genuinely varies by source (a ClusterId arrives lower-cased through OTOPCUA_ROLES and verbatim through Cluster:Roles; a ScopeId is operator free-text until the stage-7 picker lands). Path segments — every level of a scope path, and therefore PermissionTrieNode.Children — compare Ordinal, because they are browse names and Speed / speed are two different nodes that can coexist under one device. The rule is stated in full on AclScopeRef. It matters most where the deploy gate and the node are fed from different snapshots, which is exactly the split AclScopePathResolver exists to bridge: case drift there would silently drop every grant on the affected scope.

Hierarchy (design)

ACLs are evaluated against the node's scope path. NodeScope (src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/NodeScope.cs) carries a Kind that selects between two hierarchy shapes:

Equipment (UNS) kind:        Cluster → Namespace → UnsArea → UnsLine → Equipment → Tag
SystemPlatform (Galaxy) kind: Cluster → Namespace → FolderSegment(s) → Tag

On the Galaxy/SystemPlatform path each folder segment takes one trie level, so a deeply-nested Galaxy folder reaches the same depth as a full UNS path. Unset mid-path levels leave the corresponding id null and the evaluator walks only as far as the scope goes.

Each level can carry NodeAcl rows (src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/NodeAcl.cs) that grant a permission bundle to a set of LdapGroups.

Permission flags

NodePermissions (src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Enums/NodePermissions.cs), stored as an int bitmask in NodeAcl.PermissionFlags:

[Flags]
public enum NodePermissions : int
{
    None = 0,

    Browse            = 1 << 0,
    Read              = 1 << 1,
    Subscribe         = 1 << 2,
    HistoryRead       = 1 << 3,
    WriteOperate      = 1 << 4,
    WriteTune         = 1 << 5,
    WriteConfigure    = 1 << 6,
    AlarmRead         = 1 << 7,
    AlarmAcknowledge  = 1 << 8,
    AlarmConfirm      = 1 << 9,
    AlarmShelve       = 1 << 10,
    MethodCall        = 1 << 11,
    HistoryUpdate     = 1 << 12,   // OPC UA annotation / insert / delete (separate from HistoryRead)

    ReadOnly  = Browse | Read | Subscribe | HistoryRead | AlarmRead,
    Operator  = ReadOnly | WriteOperate | AlarmAcknowledge | AlarmConfirm,
    Engineer  = Operator | WriteTune | AlarmShelve,
    Admin     = Engineer | WriteConfigure | MethodCall,
}

The three Write tiers map to Galaxy's v1 SecurityClassification — FreeAccess/Operate → WriteOperate, Tune → WriteTune, Configure → WriteConfigure. SecuredWrite / VerifiedWrite / ViewOnly classifications remain read-only from OPC UA regardless of grant.

HistoryUpdate (bit 12) is a separate permission from HistoryRead so a read-only grant cannot also authorize OPC UA HistoryUpdate (annotation / insert / delete) operations. TriePermissionEvaluator maps OpcUaOperation.HistoryUpdate to this bit, closing the read⇒update hole that existed when the only history permission was HistoryRead. Note: HistoryUpdate is not included in any composite bundle (ReadOnly / Operator / Engineer / Admin) because the HistoryUpdate service surface (the actual insert/replace/delete backend RPC) is not yet implemented — a client calling HistoryUpdate still receives the SDK's default reject regardless of the grant.

Evaluator — PermissionTrie

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/:

Class	Role
PermissionTrie	Cluster-scoped trie; each node carries (GroupId → NodePermissions) grants.
PermissionTrieBuilder	Builds a trie from the current NodeAcl rows in one pass and installs it into the cache.
PermissionTrieCache	Process-singleton cache keyed on (ClusterId, GenerationId). Generation-sealed: Install(trie) adds a new generation + advances the "current" pointer; older generations are retained (in-flight requests still resolve) and GC'd by Prune. Invalidate(clusterId) drops every cached trie for a cluster. There is no AclChangeNotifier — a publish installs a new generation rather than signalling an invalidation.
TriePermissionEvaluator	Implements IPermissionEvaluator.Authorize(session, operation, scope). Walks the cluster trie for the supplied NodeScope, unions grants along the path, and returns an AuthorizationDecision. Evaluates against the session's bound generation (session.AuthGenerationId), not just "current", so a grant added/removed in a newer generation cannot take effect mid-session.

NodeScope is described above (Equipment-kind vs SystemPlatform-kind). The evaluator unions the matched grants along the path — a tag-level ACL and an area-level ACL both contribute.

Dispatch gate — IPermissionEvaluator (design; no such gate exists)

IPermissionEvaluator.Authorize(UserAuthorizationState session, OpcUaOperation operation, NodeScope scope) (default impl TriePermissionEvaluator at src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/TriePermissionEvaluator.cs) returns an AuthorizationDecision.

⚠️ The intended dispatch path — "calls it on every Read, Write, HistoryRead, Browse, Subscribe, AckAlarm, Call" — was never built. Authorize has zero production call sites. What the dispatch path really does is in What is enforced today.

Intended properties, of which only the last is true today:

• Driver-agnostic. No driver-level code participates in authorization decisions. Drivers report SecurityClassification as metadata on tag discovery; everything else was to flow through the evaluator.
• Strictly fail-closed (default-deny). Every guard path returns NotGranted — a stale session (past the staleness ceiling, decision #152), a cluster mismatch between session and scope, a missing trie, a pruned bound generation, or simply no matching grant. ⚠️ This describes the evaluator's internal behaviour when called. Because nothing calls it, the effective posture for Read/Browse/Subscribe/HistoryRead is default-ALLOW.
• Evaluator stays pure. ✅ True — TriePermissionEvaluator has no OPC UA stack dependency and is tested directly from xUnit. That purity is also why it was easy to leave unwired.

Full model

See docs/v2/acl-design.md for the complete design: trie invalidation, flag semantics, per-path override rules, and the reasoning behind additive-only (no Deny). Read it as a design document for unshipped work, not as a description of running behaviour.

Note also that the SystemPlatform hierarchy kind named above was retired with the v3 dual-namespace address space; NodeHierarchyKind now has only Equipment.

Role grant source (data-plane)

Data-plane roles come from Security:Ldap:GroupToRole (appsettings), not from the Config-DB LdapGroupRoleMapping table. That table's Role column is the AdminRole enum (Administrator/Designer/Viewer) and supplies control-plane roles only — it cannot emit the data-plane role strings the OPC UA gates read (ReadOnly, WriteOperate, WriteTune, WriteConfigure, AlarmAck). A deployment therefore must map its data-plane LDAP groups to those role strings via GroupToRole, e.g.:

"GroupToRole": {
  "ot-operators":  "WriteOperate",
  "ot-alarm-ack":  "AlarmAck"
}

⚠️ Only two role strings do anything. OpcUaDataPlaneRoles declares exactly WriteOperate and AlarmAck, and those are the only values any gate compares against. ReadOnly, WriteTune and WriteConfigure appear in the permission vocabulary but no code path reads them — mapping a group to WriteTune grants nothing, and mapping one to ReadOnly restricts nothing (reads are ungated for everyone regardless). Earlier revisions of this document listed all five as "code-true"; that was wrong for three of them.

If this mapping is absent, writes and alarm acknowledgement default-deny: they return BadUserAccessDenied even for users who authenticate successfully. (The same requirement gates both the scripted-alarm and the native Galaxy-alarm Part-9 ack/confirm/shelve paths.) Reads, browses, subscribes and history reads are unaffected — they succeed with or without any GroupToRole entry.

The two live role strings are exact and case-insensitive. In particular the alarm-ack role is AlarmAck, not AlarmAcknowledge (that spelling is the PermissionFlags ACL bit, a different vocabulary); a GroupToRole value of AlarmAcknowledge silently never satisfies the ack gate.

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Control-Plane Authorization

Control-plane authorization governs the Admin UI — who can view fleet config, edit drafts, publish generations, manage cluster nodes + credentials.

Per decision #150 control-plane roles are deliberately independent of data-plane ACLs. An operator who can read every OPC UA tag in production may not be allowed to edit cluster config; conversely a Designer may not have any data-plane grants at all.

Roles

The AdminRole enum (src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Enums/AdminRole.cs) defines three roles. Task 1.7 standardized the member names on the canonical ZB.MOM.WW.Auth CanonicalRole vocabulary (ConfigViewer → Viewer, ConfigEditor → Designer, FleetAdmin → Administrator); a data migration (CanonicalizeAdminRoles) rewrote existing rows. This was a rename, not a permission change.

Role	Capabilities
Viewer	Read-only access to drafts, generations, audit log, fleet status. (Was ConfigViewer.)
Designer	Viewer plus draft authoring (UNS, equipment, tags, ACLs, driver instances, reservations, CSV imports). Cannot publish. (Was ConfigEditor.)
Administrator	Designer plus publish, cluster/node CRUD, credential management, role-grant management. Satisfies both the FleetAdmin and DriverOperator authorization policies. (Was FleetAdmin.)

DriverOperator is an authorization policy name (kept stable), not an AdminRole member. It gates Reconnect / Restart commands against live driver instances from the Admin UI DriverStatusPanel and requires the canonical role Operator or Administrator (policy.RequireRole("Operator", "Administrator") in AddAuthorization, src/Server/ZB.MOM.WW.OtOpcUa.Security/ServiceCollectionExtensions.cs). Operator is an appsettings-only string role (not an AdminRole member); map an LDAP group to it via GroupToRole, e.g. "ot-driver-operator": "Operator". The FleetAdmin policy requires the Administrator role.

AdminUI page authorization policies (R2-05)

Every routable AdminUI page carries an explicit named-policy @attribute [Authorize(Policy = …)] — there are no bare [Authorize] (authenticated-only) config pages and no per-page Roles="…" strings. The policy names are constants on AdminUiPolicies (src/Server/ZB.MOM.WW.OtOpcUa.Security/Auth/AdminUiPolicies.cs), the single source of truth referenced by pages, AuthorizeView blocks, imperative IAuthorizationService.AuthorizeAsync checks, and endpoint groups (never string literals). All four are registered by AddOtOpcUaAuth:

Policy	Satisfied by roles	Gates
AdminUiPolicies.ConfigEditor	Administrator, Designer	The config-authoring surface: /uns, equipment, cluster/node/namespace/ACL editors, all 8 driver pages (which author live retry/breaker ResilienceConfig), Deployments, Scripts, ScriptEdit, and the /api/script-analysis/* endpoint group.
AdminUiPolicies.FleetAdmin	Administrator	RoleGrants page; the Certificates Trust/Untrust/Delete actions (AuthorizeView + server-side re-check).
AdminUiPolicies.DriverOperator	Operator, Administrator	Imperative live-ops actions only (Alerts ack/shelve, DriverStatusPanel reconnect/restart, live address pickers).
AdminUiPolicies.AuthenticatedRead	any authenticated user	The read-only dashboards, lists, and live tails (Home, Fleet, Hosts, Alerts, Certificates, cluster read views, etc.). Semantically identical to the FallbackPolicy; named so read pages carry a non-bare attribute.

Login is the only [AllowAnonymous] page (Admin-001). A reflection guard — PageAuthorizationGuardTests (tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Authorization/PageAuthorizationGuardTests.cs) — enumerates every routable type in the AdminUI assembly and fails the build if any page carries a bare [Authorize], a Roles="…" idiom, an unknown policy name, or is missing from the classification map. This is the anti-drift anchor (the repo has no bUnit): a new page fails the test until its author consciously classifies it. AdminUiPoliciesTests (tests/Server/ZB.MOM.WW.OtOpcUa.Security.Tests/AdminUiPoliciesTests.cs) pins each policy's role semantics.

In v2 the authentication + authorization stack is wired centrally by AddOtOpcUaAuth (src/Server/ZB.MOM.WW.OtOpcUa.Security/ServiceCollectionExtensions.cs), which also installs a FallbackPolicy that requires an authenticated user. Razor pages gate inline with the named-policy attribute above, e.g. @attribute [Authorize(Policy = AdminUiPolicies.ConfigEditor)]. Nav-menu sections hide via <AuthorizeView>.

Role grant source

Admin reads LdapGroupRoleMapping rows from the Config DB (src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/LdapGroupRoleMapping.cs) — the same pattern as the data-plane NodeAcl but scoped to Admin roles + (optionally) one cluster for multi-site fleets (a system-wide row, IsSystemWide = true, stacks additively with cluster-scoped rows). The RoleGrants.razor page lets Administrators edit these mappings without leaving the UI.

Headless deploy API (POST /api/deployments)

For CI / scripts that need to trigger a deployment without driving the Blazor "Deploy current configuration" button, admin-role nodes expose POST /api/deployments (DeployApiEndpoints, src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Api/DeployApiEndpoints.cs). It forwards to the same IAdminOperationsClient.StartDeploymentAsync the button calls.

Auth is a single configured secret checked from the X-Api-Key header in fixed time — deliberately orthogonal to the cookie-only web auth (OPC UA Authentication above) so automation needs no LDAP login round-trip. The endpoint is AllowAnonymous so the FallbackPolicy doesn't 401 it, and enforces the key itself. It self-disables (503) until Security:DeployApiKey is set, so it is never open by default.

curl -X POST https://<admin-host>/api/deployments \
     -H 'X-Api-Key: <Security:DeployApiKey>' \
     -H 'Content-Type: application/json' \
     -d '{"createdBy":"ci-bot"}'

Responses: 202 Accepted ({ outcome, deploymentId, revisionHash }) when a deployment was sealed, 200 for NoChanges, 409 when another deployment is in flight, 422 when rejected, 401 for a missing/wrong key, 503 when unconfigured. Set the secret via Security:DeployApiKey (env Security__DeployApiKey) on admin nodes only; treat it like any deploy credential (rotate, keep out of source).

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OTOPCUA0001 Analyzer — Compile-Time Guard

Per-capability resilience (retry, timeout, circuit-breaker) is applied by CapabilityInvoker in src/Core/ZB.MOM.WW.OtOpcUa.Core/Resilience/. A driver-capability call made outside the invoker bypasses resilience entirely — which in production looks like inconsistent timeouts, un-wrapped retries, and unbounded blocking.

OTOPCUA0001 (Roslyn analyzer at src/Tooling/ZB.MOM.WW.OtOpcUa.Analyzers/UnwrappedCapabilityCallAnalyzer.cs) fires with category OtOpcUa.Resilience and default severity Warning (per AnalyzerReleases.Shipped.md) when a method on one of the seven guarded capability interfaces (IReadable, IWritable, ITagDiscovery, ISubscribable, IHostConnectivityProbe, IAlarmSource, IHistoryProvider — all in ZB.MOM.WW.OtOpcUa.Core.Abstractions) is invoked outside a lambda passed to CapabilityInvoker.ExecuteAsync / ExecuteWriteAsync. AlarmSurfaceInvoker is not a wrapper home — its own implementation is covered transitively because it routes through the inner CapabilityInvoker.ExecuteAsync. The analyzer walks up the syntax tree from the call site, finds any enclosing invoker invocation, and verifies the call lives transitively inside that invocation's anonymous-function argument — a sibling pattern (do the call, then invoke ExecuteAsync on something unrelated nearby) does not satisfy the rule.

The xunit.v3 + Shouldly suite at tests/Tooling/ZB.MOM.WW.OtOpcUa.Analyzers.Tests/UnwrappedCapabilityCallAnalyzerTests.cs covers the common fail/pass shapes + the sibling-pattern regression guard.

The rule is intentionally scoped to async surfaces — pure in-memory accessors like IHostConnectivityProbe.GetHostStatuses() return synchronously and do not require the invoker wrap.

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Write-Outcome Self-Correction

When an OPC UA client writes a value and the driver reports a failure, the server automatically reverts the variable node to its prior value and surfaces the Bad-quality status code to the client. This prevents the node from showing a phantom Good value after a device-level write error. The revert is local to the node that received the write — no cluster coordination is required.

Additionally, an AuditWriteUpdateEvent is emitted on every write attempt (success or failure), consistent with OPC UA Part 4 audit requirements. The event carries the source node id, the requested value, and the final status code so audit log consumers can trace write outcomes without polling the node.

(Implemented in master 1d797c1c.)

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Audit Logging

• Server: authentication, certificate-validation, write, and write-denial events are logged through the regular Serilog rolling file sink; write outcomes also emit an AuditWriteUpdateEvent (see Write-Outcome Self-Correction).
• Admin: AuditWriterActor (src/Server/ZB.MOM.WW.OtOpcUa.ControlPlane/Audit/AuditWriterActor.cs) writes ConfigAuditLog rows (src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Entities/ConfigAuditLog.cs) to the Config DB for publish, rollback, cluster-node CRUD, and credential rotation. Visible on the cluster Audit page (ClusterAudit.razor) for operators with Viewer or above.

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Config secrets (${secret:} delivery)

OtOpcUa never commits secret values to appsettings*.json. Every real secret is supplied at deploy time — either as a plain environment variable, or as a ${secret:<name>} token backed by the shared ZB.MOM.WW.Secrets encrypted store.

A pre-host expander (SecretReferenceExpander.ExpandConfigurationAsync, wired in OtOpcUa.Host/Program.cs) walks the assembled configuration and rewrites every ${secret:<name>} token into its resolved plaintext before the host is built — so every downstream binder/validator (AddZbSerilog, AddOtOpcUaConfigDb, the first ValidateOnStart) sees resolved values. The store's key-encryption key (KEK) comes from the ZB_SECRETS_MASTER_KEY environment variable (Secrets:MasterKey:Source=Environment); the encrypted SQLite store lives at Secrets:SqlitePath.

The expander is fail-closed and section-agnostic: a ${secret:<name>} token whose secret is absent throws SecretNotFoundException at startup, regardless of which feature owns the key or whether that feature is enabled. Keys prefixed with _ (comment keys) are skipped, so a ${secret:...} example inside a _…Comment value is never resolved.

The five config secrets and their canonical secret names:

Config key	Owner	Secret name
Security:Jwt:SigningKey	JwtOptions	otopcua/jwt/signing-key
Security:Ldap:ServiceAccountPassword	LdapOptions	otopcua/ldap/service-account-password
Security:DeployApiKey	DeployApiEndpoints	otopcua/deploy/api-key
ConnectionStrings:ConfigDb	AddOtOpcUaConfigDb	otopcua/sql/configdb-connstr
ServerHistorian:ApiKey	ServerHistorianOptions	otopcua/historian/api-key

Delivery. By default these are delivered as plain environment variables (e.g. ServerHistorian__ApiKey=histgw_…), never committed. To deliver one from the encrypted store instead, seed it once with the secret CLI (from ZB.MOM.WW.Secrets), then supply the token in place of the literal — via env var or a deployment appsettings overlay:

secret set otopcua/historian/api-key <value>       # seed the encrypted store first
ServerHistorian__ApiKey='${secret:otopcua/historian/api-key}'

Only switch a value to a ${secret:} token after the secret is seeded — an unseeded token fails the boot fail-closed. Do not commit the KEK (ZB_SECRETS_MASTER_KEY) or any secret value.

For the production posture needed so every clustered node (admin, driver, and any fused role) resolves the same secrets from the same store, see docs/operations/2026-07-16-secrets-clustered-master-key.md.

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Troubleshooting

Certificate trust failure

Check {PkiStoreRoot}/rejected/ for the client's cert. As a FleetAdmin, use the Admin UI Certificates page's Trust action to move it into trusted/ (or copy the .der to trusted/certs/ by hand); the SDK trust list reloads on the next handshake.

LDAP users can connect but fail authorization

Verify (a) Security:Ldap:GroupAttribute (default memberOf) returns the user's groups, (b) Security:Ldap:GroupToRole maps those groups to the expected roles, and (c) a NodeAcl grant exists at some level of the node's scope path that unions to the required permission. The data-plane evaluator is strictly default-deny — there is no fail-open mode to fall back on.

LDAP bind rejected as "insecure"

Set Security:Ldap:Transport = "Ldaps" (or "StartTls") with the matching port (636 for AD Ldaps), or temporarily set Security:Ldap:AllowInsecure = true in dev. Production Active Directory increasingly refuses plain-LDAP bind under LDAP-signing enforcement.

Stale ACL trie after a publish

A publish installs a new generation into PermissionTrieCache via PermissionTrieBuilder rather than signalling an invalidation; the evaluator binds each session to a generation. If grants appear stale, confirm the new generation was installed (publish completed) and that sessions re-resolved their auth state — a session past its staleness ceiling fails closed and must re-authenticate. As a last resort PermissionTrieCache.Invalidate(clusterId) drops a cluster's cached tries.