Add local DNS resolver for exits

[acl1704]

Potentially add an option for exit relays to also install Unbound or other local DNS resolver in lieu of ISP or public resolvers.

Adding local DNS would be an option for mitigating https://github.com/flxn/tor-relay-configurator/issues/1

[flxn]

Will look into this. Do you use such a solution on your own exit node? Could you provide a link to more information about this?

[ghost]

@flxn https://trac.torproject.org/projects/tor/wiki/TorRelayGuide

Debian:

apt install unbound -y
# Allow the modification of the file
chattr -i /etc/resolv.conf

# Disable previous DNS servers
sed -i "s|nameserver|#nameserver|" /etc/resolv.conf
sed -i "s|search|#search|" /etc/resolv.conf

# Set localhost as the DNS resolver
echo "nameserver 127.0.0.1" >> /etc/resolv.conf

# Disallow the modification to prevent the file from being overwritten by the system.
# Use -i to enable modifications
chattr +i /etc/resolv.conf