Security At Opc Ua; Security Settings - Siemens SIMATIC ET 200AL System Manual

9.2

Security at OPC UA

9.2.1

Security settings

Addressing risks
OPC UA allows the exchange of data between different systems, both within the process
and production levels and to systems at the control and enterprise level.
This possibility also entails security risks. That is why OPC UA uses a range of security
mechanisms:
● Verification of the identity of OPC UA server and clients.
● Checking of the identity of the users.
● Signed/encrypted data exchange between OPC UA server and clients.
These security policies should only be bypassed in cases where it is absolutely necessary:
● During commissioning
● In stand-alone projects without external Ethernet connection
If you have selected the endpoint "None" for "UA Sample Client" of the OPC Foundation, for
example, the program issues a clear warning:
Note
Disabling security policies you do not want
If you have selected all security policies (default setting) in the secure channel settings of the
S7-1500 OPC UA server – in other words the endpoint "None" (no security) – non-secure
data traffic (neither signed nor encrypted) between the server and client is also possible. The
OPC UA server of the S7-1500 CPU also sends its public certificate to the client at "None"
(No security). And some clients check this certificate. However, the client does not send a
certificate to the server. The identity of the client remains unknown with "None". Each OPC
UA client can then connect to the server irrespective of any subsequent security settings.
When configuring the OPC UA server, make sure that only security policies that are
compatible with the security concept for your machine or plant are selected. All other security
policies should be disabled.
Recommendation: Use the setting "Basic256Sha256", which means that the server only
accepts Sha256 certificates.
Communication
Function Manual, 12/2017, A5E03735815-AF
OPC UA communication
9.2 Security at OPC UA
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