The DotVPN DNS over TLS Killswitch feature addresses several critical privacy and security concerns:
DNS Leaks: Without a killswitch, if the DotVPN connection drops, your device may revert to using your default, often less secure, ISP-provided DNS servers. This exposes your DNS queries, revealing browsing activity.
Unencrypted DNS Traffic: Standard DNS queries are sent in plain text, making them vulnerable to eavesdropping and manipulation. DNS over TLS (DoT) encrypts this traffic, but only when actively used.
Lack of Automatic Protection: Users may forget to manually configure DNS settings, leaving them vulnerable even when using DotVPN.
Circumventing VPN Protection: Malicious actors could potentially intercept DNS requests and redirect them, even with an active DotVPN connection, if the DNS settings aren't properly secured.
Common errors encountered when implementing DotVPN DNS over TLS killswitch functionality include:
Incorrect DNS Server Addresses: Using the wrong DNS server addresses will prevent DNS resolution.
Firewall Interference: Firewalls may block outbound DoT traffic on port 853.
Configuration Conflicts: Conflicts between network manager settings and system-wide DNS configurations.
Missing Dependencies: Required packages for DoT, like stubby or systemd-resolved, might be missing.
To diagnose issues with the DotVPN DNS over TLS killswitch:
Check DNS Resolution: Use nslookup google.com to see if DNS resolution is working. If it fails, there's a DNS problem.
Verify DNS Server: Use resolvectl status (if using systemd-resolved) or inspect /etc/resolv.conf to see which DNS servers are being used. Ensure they are the correct DoT servers.
Firewall Rules: Check firewall rules to ensure outbound traffic on port 853 is allowed.
VPN Connection: Verify the DotVPN connection is active and stable.
Here are commands to configure DotVPN DNS over TLS killswitch (example using systemd-resolved):
Edit resolved.conf:
sudo nano /etc/systemd/resolved.conf
Add/modify the following lines:
[Resolve]
DNS=1.1.1.1#cloudflare-dns.com 1.0.0.1#cloudflare-dns.com
DNSOverTLS=yes
DNSStubListener=no
Restart systemd-resolved:
sudo systemctl restart systemd-resolved
Configure iptables (example):
sudo iptables -A OUTPUT -m owner --gid-owner nobody -p udp --dport 53 -j REJECT --reject-with icmp-port-unreachable
sudo iptables -A OUTPUT -m owner --gid-owner nobody -p tcp --dport 53 -j REJECT --reject-with icmp-port-unreachable
sudo iptables -A OUTPUT ! -o tun0 -p udp --dport 53 -j REJECT --reject-with icmp-port-unreachable
sudo iptables -A OUTPUT ! -o tun0 -p tcp --dport 53 -j REJECT --reject-with icmp-port-unreachable
(Replace tun0 with your DotVPN interface name.)
To further harden the DotVPN DNS over TLS killswitch:
Disable DNS Fallback: Ensure your system doesn't fall back to unencrypted DNS if DoT fails.
Secure DNS Server Selection: Only use reputable and trusted DoT servers.
Regularly Update: Keep your system and DNS resolver software updated.
Monitor Logs: Regularly check system logs for DNS-related errors.
Perform these sanity checks to ensure the DotVPN DNS over TLS killswitch is working:
Disconnect DotVPN: Disconnect from DotVPN and verify that DNS resolution fails. This confirms the killswitch is active.
Check DNS Server: With DotVPN connected, use resolvectl status or inspect /etc/resolv.conf to confirm you're using the configured DoT servers.
Test DNS Leak: Use online DNS leak test tools to verify your real IP address and ISP DNS servers are not being exposed.