Siemens SIMATIC S7-400 Operating Instructions Manual page 37

● Protection of the passwords of the OPC UA client program blocks
Protect the passwords stored in data blocks for the client blocks from being viewed. The
procedure is described below.
● Logging function
Enable the function in the Security configuration and check the logged events regularly
for unauthorized access.
Know-how protection of blocks (STEP 7 V5)
You can prevent the contents of data blocks (e.g. passwords) being read out by protecting
the block with the "KNOW_HOW_PROTECT" option. Follow the steps outlined below in
STEP 7:
1. Select the DB in the block folder.
2. Open the block in the editor.
3. Close the block in the editor.
4. Generate a source from the block in the editor.
5. Select the source of the DB in the sources folder.
6. Open the source.
7. Insert an empty line in the header of the source and write "KNOW_HOW_PROTECT" in
this line.
8. Compile the source.
Result: The block is protected. You can recognize this by the padlock symbol in the block
folder.
If you want to change parameters, for example a password, in a DB later, remember the
following; The contents of a DB with know-how protection are no longer visible and can only
be changed via the source or by direct assignment of parameters.
Know-how protection of blocks (STEP 7 Professional)
You will find information on the procedure in the STEP 7 information system under the
keyword "Know-how protection".
Passwords
● Define rules for the use of devices and assignment of passwords.
● Regularly update the passwords to increase security.
● Only use passwords with a high password strength. Avoid weak passwords for example
"password1", "123456789" or similar.
● Make sure that all passwords are protected and inaccessible to unauthorized personnel.
See also the preceding section for information on this.
● Do not use one password for different users and systems.
CP 443-1 OPC UA
Operating Instructions, 01/2017, C79000-G8976-C427-02
Configuration and operation
4.2 Security recommendations
37