Security Hardening

When to use this skill

Load when users ask about access control, security, auditing, or user management.

RBAC (Role-Based Access Control)

• Create roles: CREATE ROLE analyst
• Grant permissions: GRANT SELECT ON db.* TO analyst
• Assign to users: GRANT analyst TO user1
• Hierarchical: roles can inherit from other roles
• Check grants: SHOW GRANTS FOR user1

Row Policies

• Restrict row access per user: CREATE ROW POLICY p ON db.table FOR SELECT USING tenant_id = currentUser()
• Policies are AND-ed together
• Use for multi-tenant data isolation
• Check policies: system.row_policies

Quotas

• Limit resource usage per user/IP: CREATE QUOTA q FOR user1 ... LIMIT max_queries = 100
• Quota intervals: per hour, per day, etc.
• Limits: max_queries, max_result_rows, max_read_rows, max_execution_time
• Monitor: system.quota_usage

Network Security

• Restrict user access by IP: CREATE USER u HOST IP '10.0.0.0/8'
• Use TLS for client connections
• Inter-server encryption for replication
• Separate ports for internal vs external access

Audit Logging

• Enable system.session_log for login tracking
• system.query_log records all queries with user info
• system.text_log for server-level events
• Configure log retention with TTL

Best Practices

• Principle of least privilege — grant only needed permissions
• Use roles, not direct user grants
• Separate read-only and admin users
• Enable quotas for all non-admin users
• Regular audit of grants and access patterns
• Use readonly = 1 setting for monitoring connections