# Secure servers

<dl class="api-definition">
<dt>Concept</dt>
<dd><a href="/docs/development/opcua/security/server">Secure servers</a></dd>
</dl>

| Type | Description |
|---|---|
| [OpcAccessControlEntry](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolentry/) | Represents the access control settings of a single [OpcPrincipal](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcprincipal/) in an [OpcAccessControlList](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrollist/): the operations allowed or denied and the endpoints enabled or disabled for the principal. |
| [OpcAccessControlList](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrollist/) | Provides the abstract base class of the access control lists of an [OpcServerSecurity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserversecurity/), which authenticate the identity tokens of one [OpcAccessControlTokenType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontroltokentype/) and maintain one [OpcAccessControlEntry](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolentry/) per [OpcPrincipal](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcprincipal/). |
| [OpcAccessControlMode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolmode/) | Specifies how an [OpcAccessControlEntry](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolentry/) evaluates an operation which has neither been allowed nor denied explicitly and an endpoint which has neither been enabled nor disabled explicitly. |
| [OpcAccessControlRole](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolrole/) | Represents a single access control role [OpcPrincipal](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcprincipal/) instances can be a member of. |
| [OpcAccessControlTokenType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontroltokentype/) | Specifies the type of the user identity tokens an access control list of a server is responsible for. |
| [OpcAnonymousAcl](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcanonymousacl/) | Represents the access control list of an [OpcServerSecurity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserversecurity/) which authenticates anonymous identity tokens. |
| [OpcAuthenticationLimits](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcauthenticationlimits/) | Provides authentication options used by a server application instance to control the limits of authentications between the opponent applications. |
| [OpcCertificateAcl](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opccertificateacl/) | Represents the access control list of an [OpcServerSecurity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserversecurity/) which authenticates X.509 certificate identity tokens using the [OpcCertificateIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificateidentity/) instances of its entries. |
| [OpcCertificateChangedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatechangedeventargs/) | Provides the event data for 'CertificateChanged' events. |
| [OpcCertificateIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificateidentity/) | Represents the identity of a user which is described by a certificate. |
| [OpcCertificateIdentityTokenInfo](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificateidentitytokeninfo/) | Describes an identity a client stated by a certificate. |
| [OpcCertificateManager](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatemanager/) | Provides a set of static (Shared in Visual Basic) methods to manage certificates. |
| [OpcCertificateRequestedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificaterequestedeventargs/) | Provides the event data for the [CertificateRequested](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopcapplicationinstance/members#certificaterequested) event. |
| [OpcCertificateSettings](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatesettings/) | Defines the setup of an application instance certificate. |
| [OpcCertificateStoreInfo](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatestoreinfo/) | Represents a certificate store, which provides access to the certificates stored at its [Path](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatestoreinfo/members#path). |
| [OpcCertificateStores](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatestores/) | Provides access to the set of OPC UA predefined certificate stores typically used by an OPC UA application to maintain its certificates. |
| [OpcCertificateValidationFailedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatevalidationfailedeventargs/) | Provides the event data for 'CertificateValidationFailed' events. |
| [OpcCertificateValidationRules](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatevalidationrules/) | Defines the different validation rules which can be additionally applied to the default validation rules of a certificate validation. |
| [OpcEndpointIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcendpointidentity/) | Represents the identity of an endpoint, which consists of its URL and its security policy. |
| [OpcIdentityToken](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcidentitytoken/) | Represents the user identity token a client passes to the server to identify the user of a session. |
| [OpcIdentityTokenInfo](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcidentitytokeninfo/) | Describes the identity a client stated, without any secret it stated along with it. |
| [OpcOperationLimits](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcoperationlimits/) | Provides operation options used by a server application instance to control the limits of operation between the opponent applications. |
| [OpcOperationType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcoperationtype/) | Represents the type of an operation which an [OpcAccessControlEntry](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolentry/) allows or denies. |
| [OpcPrincipal](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcprincipal/) | Represents a user of the server by its [OpcIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcidentity/), to which the entries of the access control lists and the access control roles apply. |
| [OpcRequestType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcrequesttype/) | Specifies the type of a request a client sends to the server, named after the service the request calls. |
| [OpcRequestValidatingEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcrequestvalidatingeventargs/) | Provides the event data for the [RequestValidating](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/members#requestvalidating) event. |
| [OpcSecurityPolicy](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcsecuritypolicy/) | Describes the configuration used to secure the message exchange. |
| [OpcServer](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/) | Represents an OPC UA server which provides the address space defined by its [NodeManagers](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/members#nodemanagers) to its clients. |
| [OpcServerBinding](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserverbinding/) | Provides a set of options used when binding a server instance to a network interface. |
| [OpcServerIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserveridentity/) | Represents the identity of a user of the server, which is identified by a user name and a password. |
| [OpcServerSecurity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserversecurity/) | Provides the security options of a server, including the access control lists which authenticate the identity tokens of the clients and determine the operations and endpoints available to them. |
| [OpcServerSecurityRoles](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserversecurityroles/) | Provides the default [OpcAccessControlRole](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcaccesscontrolrole/) instances usually known to the [OpcServer](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/). |
| [OpcSession](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcsession/) | Represents a session which a client has created on the server. |
| [OpcSessionActivationFailedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcsessionactivationfailedeventargs/) | Provides the data of the [SessionActivationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/members#sessionactivationfailed) event. |
| [OpcSessionActivationFailedEventHandler](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcsessionactivationfailedeventhandler/) | Represents the method that handles the [SessionActivationFailed](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserver/members#sessionactivationfailed) event. |
| [OpcTransport](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctransport/) | Provides transport options used by an application instance to control the behavior of the operation, communication and data flow between the opponent applications. |
| [OpcUserIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcuseridentity/) | Represents the identity of a user described by an OPC UA user identity token (e.g. an anonymous user, a user name or a certificate). |
| [OpcUserNameAcl](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcusernameacl/) | Represents the access control list of an [OpcServerSecurity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserversecurity/) which authenticates user name identity tokens using the [OpcServerIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.server.opcserveridentity/) instances of its entries. |
| [OpcUserNameIdentityToken](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcusernameidentitytoken/) | Represents the user identity token of a client which identifies a user using a user name and a password. |
| [OpcUserNameIdentityTokenInfo](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcusernameidentitytokeninfo/) | Describes an identity a client stated by a user name, without its password. |