A DNS leak occurs when your computer runs a DNS query outside of an established, encrypted tunnel.
For OpenVPN users:
Tunnelr runs a local DNS recursor on every exit node. While our OpenVPN server configurations are set to push the DNS settings to you via the config, it is nevertheless possible that your computer will not honor this setting and continue using the DNS servers assigned via DHCP by your ISP/router/etc.
Please verify that you are using the 10.0.8.1 resolver when connected to one of our nodes, to ensure that you are not leaking DNS requests outside of the tunnel.
For OpenSSH users:
Due to the nature of SOCKS support - the support for eliminating DNS leaks varies from application to application and you will have to do some additional research to see whether your program supports making DNS requests via the SOCKS proxy
For example: to enable SOCKS based DNS requests in Firefox and Thunderbird, you can open the 'about:config' settings page and adjust the 'network.proxy.socks_remote_dns' setting to 'true'.