Blog | G5 Cyber Security

ISP Hostname Visibility in VirtualBox

G5 Cyber Security

TL;DR

Your ISP can see the hostname of your VirtualBox virtual machines if you don’t take steps to hide it. This is because DNS requests are typically handled by your ISP’s servers. We’ll cover how this happens and several ways to prevent it, ranging from simple changes to more advanced configurations.

Understanding How Your ISP Sees Hostnames

When a virtual machine tries to access a website (e.g., google.com), it needs to translate that human-readable name into an IP address. This is done through DNS (Domain Name System). Normally, your VM uses the network settings inherited from your host operating system, which in turn uses your ISP’s DNS servers by default.

Every time your VM makes a DNS request, it’s sent to your ISP. They log this information, including the hostname you requested. While they don’t necessarily know what is doing the requesting (just an IP address), that IP address can be traced back to you.

Steps to Hide Hostnames from Your ISP

  1. Change DNS Servers
    • The easiest way to prevent your ISP from seeing your DNS requests is to use a public DNS server like Cloudflare (1.1.1.1), Google Public DNS (8.8.8.8 and 8.8.4.4), or OpenDNS.
    • On Windows: Go to Network Connections, right-click your network adapter, select Properties, find Internet Protocol Version 4 (TCP/IPv4), click Properties, then select “Use the following DNS server addresses”. Enter your preferred and alternate DNS servers.
    • On Linux: Edit your `/etc/resolv.conf` file (you may need root privileges). Add or modify lines like this: 
      nameserver 1.1.1.1
nameserver 8.8.8.8
    • On macOS: Go to System Preferences > Network, select your network connection, click Advanced, then DNS. Add your preferred DNS servers using the ‘+’ button.
  2. VirtualBox Networking Mode – Host-Only Adapter
    • Using a Host-Only adapter creates a private network between your host machine and the VM. This means all traffic stays within your computer, and doesn’t go through your ISP’s network until it leaves your host machine.
    • In VirtualBox Manager, select your VM, then Settings > Network. Choose “Host-only Adapter” for Adapter 1.
  3. VirtualBox Networking Mode – Internal Network
    • Similar to Host-Only, an Internal Network creates a completely isolated network within VirtualBox. No traffic goes through your host machine or the internet directly from the VM. This is useful if you don’t need internet access inside the VM.
    • In VirtualBox Manager, select your VM, then Settings > Network. Choose “Internal Network” for Adapter 1.
  4. Use a VPN on Your Host Machine
    • A VPN encrypts all internet traffic from your host machine, including the traffic from your VMs. This hides your IP address and DNS requests from your ISP.
    • Install and connect to a reputable VPN service before starting your VirtualBox VM.
  5. Configure DNS within the Guest OS (Advanced)
    • You can configure the guest operating system inside your VM to use specific DNS servers, overriding the host machine’s settings. This is useful if you want more control over DNS resolution within the VM itself.
    • Follow the steps in step 1, but do it *inside* the virtual machine’s operating system.

Important Considerations

Exit mobile version