Contractor Network Security: Preventing Data Leakage

TL;DR

Working for multiple clients means juggling lots of sensitive information. This guide shows you how to keep each client’s data separate and avoid accidental leaks, covering everything from network setup to daily habits.

Protecting Client Data: A Contractor’s Guide

1. Dedicated Networks & Devices
• Separate Wi-Fi Networks: Don’t use the same home/office Wi-Fi for all clients. Create a separate network (or VLAN if you have managed switches) for each client. This is your first line of defence.

  # Example using nmcli on Linux:
  mcli wifi add wifiname "ClientA_WiFi" ssid "ClientA_SSID" password "ClientAPassword" security WPA2-PSK

• Dedicated Devices: Ideally, use a separate laptop for each client. If that’s not possible, consider virtual machines (VMs – see step 3).
• Physical Separation: If using VMs isn’t feasible, be *extremely* careful about what you copy between clients on the same device.
2. Strong Authentication & Access Control
• Unique Passwords: Use strong, unique passwords for each client’s accounts and services. A password manager is essential.
• Multi-Factor Authentication (MFA): Enable MFA wherever possible. This adds a crucial extra layer of security.
• Least Privilege: Only access the data you *need* to for your work. Ask clients for limited accounts with restricted permissions.
3. Virtualisation & Containerisation
• VMs (Virtual Machines): Use software like VirtualBox, VMware Workstation Player or Hyper-V to create isolated environments for each client.

  # Example using VirtualBox command line:
  VBoxManage createvm --name "ClientA_VM" --ostype Ubuntu_64 --register

• Containers (Docker): For development work, containers provide even lighter-weight isolation. Be aware of potential container escape vulnerabilities.
4. Data Storage & Backup
• Separate Storage: Store each client’s data in a separate folder or drive (physical or virtual). Never mix client files.
• Encryption: Encrypt sensitive data at rest and in transit. Use tools like VeraCrypt for full disk encryption, or built-in OS features.
• Secure Backups: Backup each client’s data separately. Store backups securely (e.g., encrypted cloud storage with MFA). Test your backups regularly!
5. Network Monitoring & Security Tools
• Firewall: Use a firewall on all devices to control network traffic.
• Antivirus/Anti-Malware: Keep antivirus software up-to-date.
• VPN (Virtual Private Network): Use a VPN when connecting to client networks, especially public Wi-Fi.
6. Secure Communication & File Transfer
• Encrypted Email: Use end-to-end encrypted email for sensitive communications.
• Secure File Sharing: Avoid using personal file sharing services (Dropbox, Google Drive) for client data. Use client-approved methods or secure transfer tools like SFTP/SCP.

  # Example using SCP:
  scp /path/to/local/file username@clientaserver:/path/to/remote/directory

7. Daily Habits & Awareness
• Log Out: Always log out of client accounts when you’re finished working.
• Browser Profiles: Use separate browser profiles for each client to isolate cookies and browsing history.
• Regular Audits: Periodically review your setup and processes to ensure they are still secure.
• Client Agreements: Have clear agreements with clients about data security responsibilities.