This blog describes how to setup secure inbound communication using client certificates, it describes the different configuration options available and gives a step by step description what needs to be configured where.
Setup Secure HTTP Inbound Connection with Client Certificates
A typical task in an integration project is to connect remote systems to the SAP Cloud Integration Tenant. Before going into detailed configuration of the inbound communication lets first have a short look at the basics.
Basics of Secure System Configuration
The remote system can act either as a sender or a receiver of messages. The setup and the detailed configuration procedure differ according to the communication direction that is being set up: whether a remote system is supposed to send a message to the integration platform or the other way round.
For more detailed information about the different authentication and authorization options refer to the SAP Cloud Platform Integration Documentation, section ‘Connecting a Customer System to Cloud Integration’.
This blog focuses on inbound communication. Outbound communication configuration is described in blog ‘How to Setup Secure Outbound HTTP Connection using Keystore Monitor’.
Secure Inbound Communication
For HTTPS based communication towards Cloud Integration Tenant no keystore in the Integration tenant needs to be maintained. Sender system and Load Balancer need to get the certificates and keys configured as described below. In Integration Tenant only certificates for Client Certificate based authorization are to be maintained, either in Certificate-to-User Mapping or directly in the integration flow.
Configurations in Sender System
For secure inbound communication via HTTPS the sender system must trust the Load Balancer, for this it must have the root certificate of one of those certification authorities (CAs) in its trust store, that are supported by the load balancer.
Furthermore, if you want to use Client Certificate authentication, the sender system keystore needs to contain a key pair, whose certificate is signed by one of the CAs supported by the load balancer.
More information on the supported CAs: Load Balancer Root Certificates Supported by SAP.
Configurations in Cloud Integration Tenant
For secure inbound communication using Client Certificates, in the cloud integration tenant only the certificates needed for the Client Certificate based authorization check need to be configured. In general, there are two configuration options available:
- Role based Authorization
- Maintain Certificates directly in the integration flow
Note: SAP does not recommend to use Basic authentication because of security aspects, details can be found in documentation chapter ‘Basic Authentication’.
Role Based Authorization
The recommended configuration is to use User Role as authorization option in the integration flow sender channel and import the client certificates in the Certificate-to-User Mapping monitor.
Configure Sender Channel
You configure the authorization option in the sender channel in the integration flow. For the adapters supporting client certificate based authorization you find the authorization configuration option in the Connection tab. If User Role is selected an additional entry field for the role to be checked is shown.
The default role provided by SAP is ESBMessaging.send, this role can be used if no additional, integration flow specific authorization checks are needed. In case only specific certificates/users shall be allowed to send messages to this integration flow you can enter your own role in this field and create the role in the Cloud Platform Role Management as described further down in the blog.
To configure and deploy Integrations flows in WebUI your user needs the Group Role AuthGroup.IntegrationDeveloper or Single Roles WebToolingWorkspace.Read,
WebTooling.IntegrationFlowConfigure, GenerationAndBuild.generationandbuildcontent and
Configure Client Certificate in User-to-Certificate Mapping Monitor
The client certificates, that will be used to send messages to the integration flow, have to be configured in the Certificate-to-User Mapping Monitor. The monitor is available in the Operations View in section Manage Security.
In the monitor a user name is assigned to the client certificate. To setup the client certificate based communication upload the client certificate via the Add Button at the top of the monitor and assign a user name. The user name does not need to exist in the SAP Identity Provider as SAP Community Network (SCN) user.
To configure Certificate-to-User Mappings your user needs the Group Role AuthGroup.Admin or Single Roles IntegrationOperationServer.read, NodeManager.deploysecuritycontent and
Assign Role to User in Authorization Management
The user created in the Certificate-to-User Mapping has to be assigned to the user role configured in the sender channel to allow sending messages to the integration flow. This is to be done in SAP Cloud Platform Cockpit.
Under Subscriptions select the application for the worker node, the one with the suffix iflmap or hcioem (depending on profile). In section Roles you can create your own roles. The only SAP delivered role on the worker node is ESBMessaging.send. You add additional roles using the New Role option at the top of the monitor. Afterwards assign the new role to the user set in the User-to-Certificate mapping.
You can also create groups for users and assign the groups to the custom role.
To configure roles in SAP Cloud Platform Cockpit you need to be administrative member of the subscriber account.
Configure Certificates directly in Integration Flow
The second option is to configure the certificates for the authorization check directly in the integration flow. But this option is not recommended because changes to the certificate will always cause short downtimes.
Configure Sender Channel
In the sender channel in the integration flow authorization can be configured for the adapters supporting client certificate based authorization. The authorization configuration option is available in the Connection tab of the channel. If Client Certificate is selected a table is shown, where you can add the client certificates. Via Add Button add a new row to the table, in the row you can open the upload dialog for a certificate. Via Upload from File System you can browse the certificate file and add it to the channel.
You can add several certificate to the integration flow sender channel. But be aware that each update in the integration flow needs a redeployment of the integration flow and so is always causing a short downtime. This means, also during certificate renewal of the client certificate you must redeploy the integration flow, causing a short downtime. Exactly because of this disadvantage SAP recommends to use the Role Based Authorization option with user to certificate mapping.
To configure Integrations flows your user needs the Group Role AuthGroup.IntegrationDeveloper or Single Roles WebToolingWorkspace.Read, WebTooling.IntegrationFlowConfigure, GenerationAndBuild.generationandbuildcontent and NodeManager.deploycontent.