From NetBSD Wiki

Introduction

Normally a user can use the ps command to see any process running on a system.
A nice additional security measure is to hide these processes.
A user may be able to "see" only her own processes thanks to the security.curtain sysctl option.

Execution

Run following command as a user with root privileges:

# sysctl -w security.curtain=1

Now type as normal user:

# ps auxww

You should be able to see only processes belonging to your user.

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