Connection Tab

Here you define the security-related connection data for the connection to the MQTT server.

Last Will Settings

Settings for the Last Message if Connection Interrupted

Field

Description

Topic Name

This is the name of the last message that is to be sent from the MQTT server to PCo if the connection between PCo and the MQTT server is interrupted. This message is called a last will message.

If you enter something here, you can enter a message text in the Message field that you want to be sent in the following situations:

  • The MQTT server discovers an I/O error or a network outage.

  • The PCo client does not manage to communicate with the server within the defined keep--alive interval.

  • The PCo client closes the network connection without first sending a DISCONNECT packet.

  • The MQTT server closes the network connection due to a protocol error.

Message

Here you enter the message text that you want to be sent from the MQTT server to PCo if the connection is interrupted.

QoS
Quality of service: To make sure that a a sent message reaches the recipient, MQTT defines three different quality of service (QoS) levels with which a message can be sent:

  • 0 - At Most Once

    When PCo receives the last message, no confirmation is to be sent to the MQTT server.

  • 1 - At Least Once

    PCo sends the Publish Acknowledge Packet (PUBACK packet) to the MQTT server as soon as the last will message has arrived.

  • 2 - Exactly Once

    PCo sends the Publish Received Packet (PUBREC) to the MQTT server as soon as the last will message has arrived. The server responds with the Publish Release Packet (PUBREL). PCo responds with the Publish Complete Packet (PUBCOMP).

Retain Message

By selecting this checkbox you define that the MQTT server has to store the last will message and send it to PCo, even if PCo is currently offline.

Client Certificate

Settings for the Client Certificate

Field

Description

Certificate

Here you can select a client certificate with a private key if you want to set up a secure connection (mqtts or wss).

Certificate Folders

Settings for the Certificate Folders

Field

Description

Store Type
Here you select the store for the server certificate of the MQTT server that you want to be validated. The following types are supported:

  • Microsoft certificate store

    When a connection is being established, with this setting, PCo automatically searches in the Microsoft certificate store folder for a server certificate.

  • File system certificate store

    With this option, you can specify the store location for the certificates, which PCo is to trust, in the file system.

Trusted Certificates

Here you can specify the folder in which the trusted certificates are stored.

If you have selected the Microsoft certificate store, this is the folder for the trusted root certification authorities. The system proposes this automatically.

If you have chosen the file system certificate store, a directory is proposed in the file system with the following subfolders:

  • certs: Folder for trusted certificates

    If you store a certificate from the certificate chain in this folder, this certificate is trusted in the check. The certificate is regarded as not trusted if there is no certificate from the certificate chain stored here.

  • crls: Folder for certificate revocation lists

  • private: Folder for private certificates that are not used for Windows

If you choose Browse, a dialog box appears where you can select another folder.

Issuer Certificates

Here you can specify the folder in which the certificates of a trusted issuer are stored.

If you selected the Microsoft certificate store, this is the folder for the intermediate certificate authorities. This is proposed automatically.

If you have selected the file system certificate store, a directory is proposed in the file system with the subfolder certs. This folder is used to complete the certificate chain if the server does not send the complete certificate chain.

Rejected Certificates

Here you can specify the folder in which the rejected certificates are stored.

If you are using the Microsoft certificate store, select Untrusted Certificates here.

If you have selected the file system certificate store, use a directory in the file system with the subfolder certs (folder for rejected certificates).

Certificate Validation Options

Validation Options

Field

Description

Revocation Check
In this field you define how the revocation check of the server certificate is to be performed. You have the following options:

  • No Check on Revoked Certificates

    No check is carried out.

  • Check Online Revocation Lists

    The online check is a secure procedure but it can have a negative impact on performance.

  • Check Offline Revocation Lists

    • If you are using the Microsoft certificate store, you need to copy all the relevant certificate revocation lists into the Trusted Root Certification Authorities directory.

    • If you have selected the file system certificate store, you need to copy all related certificate revocation lists as .crl files into the revocation list folder.

Revocation Check Scope
Indicates the scope of the revocation check. You have the following options:

  • Check End Certificate Only

    Only the last certificate in a certificate chain is checked.

  • Exclude Root Certificate from Check

  • Check Entire Chain

    All certificates in a certificate chain are checked.

Ignore Server Host Name

If you select this checkbox, the check results of the server host name are not taken into consideration.

During the check, a comparison is made with the domain name system (DNS) name that is included in the certificate. The DNS name is the name of a server in a domain, for example: mo-90dxxxxxx.mo.sap.corp.

Ignore Validity Period

If you select this checkbox, you define that the validity period of the server certificate and the certificates in the certificate chain are not to be taken into consideration.

Proxy Settings

Field

Description

Proxy URI

You use this setting if you want the MQTT server to be connected using a proxy. PCo supports two types of proxy URIs:

  • http:

  • socks5:

User Name

User name for the proxy (optional)

Password

Password for the proxy (optional)
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