====== Caching only DNS ======

  * [[https://www.digitalocean.com/community/tutorials/how-to-configure-bind-as-a-caching-or-forwarding-dns-server-on-ubuntu-14-04]]
  * [[https://aacable.wordpress.com/2011/07/04/setup-a-forwarding-caching-only-dns-server-on-ubuntu/]]


===== Installation auf Ubuntu 24.04 =====

<code bash 1. Prüfen ob systemd-resolved bereits aktiv ist:>
systemctl status systemd-resolved
</code>

<code bash 2. Konfiguration anpassen:>
sudo vim /etc/systemd/resolved.conf
</code>

<code bash 3. Diese Einstellungen aktivieren:>
[Resolve]
DNS=8.8.8.8 1.1.1.1
Cache=yes
DNSStubListener=yes
</code>

<code bash 4. Service neu starten:>
sudo systemctl restart systemd-resolved
sudo systemctl enable systemd-resolved
</code>

<code bash 5. DNS-Konfiguration aktualisieren:>
sudo ln -sf /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf
</code>


===== Installation auf Ubuntu 16.04 =====

  > apt install bind9 bind9utils

<file c /etc/default/bind9>
# run resolvconf?
RESOLVCONF=no

# startup options for the server
OPTIONS="-4 -u bind"
</file>

<file c /etc/bind/named.conf.options>
//
// Caching only DNS Server
// https://fxdata.cloud/tutorials/configure-bind-as-a-caching-or-forwarding-dns-server-on-ubuntu-14-04
//
//acl goodclients {
//      10.10.0.9;
//      127.0.1.1;
//      127.0.0.1;
//      localhost;
//      localnets;
//};

acl goodclient {
    localhost;
    localnets;
};

options {
        directory "/var/cache/bind";

        // If there is a firewall between you and nameservers you want
        // to talk to, you may need to fix the firewall to allow multiple
        // ports to talk.  See http://www.kb.cert.org/vuls/id/800113
        // If your ISP provided one or more IP addresses for stable
        // nameservers, you probably want to use them as forwarders.
        // Uncomment the following block, and insert the addresses replacing
        // the all-0's placeholder.

        // forwarders {
        //      0.0.0.0;
        // };

        recursion yes;

//      allow-query {
//              goodclients;
//      };

        forwarders {
                8.8.8.8;    // Google DNS 1
                4.4.4.4;    // Google DNS 2
                1.1.1.1;    // popular DNS
        };

        forward only;

        //========================================================================
        // If BIND logs error messages about the root key being expired,
        // you will need to update your keys.  See https://www.isc.org/bind-keys
        //========================================================================
        //dnssec-validation auto;

        dnssec-enable yes;
        dnssec-validation yes;

        auth-nxdomain no;    # conform to RFC1035
        //listen-on-v6 { any; };
        listen-on-v6 { none; };

        #----------------------------------------------------------------------#

        query-source address * port 53;

        listen-on {
                127/8;
        };

        allow-query { goodclient; };
};
</file>

  > service bind9 restart


===== Installation auf Ubuntu 14.04 =====

  > apt install bind9 bind9utils

<file c /etc/default/bind9>
# run resolvconf?
RESOLVCONF=no

# startup options for the server
OPTIONS="-4 -u bind"
</file>

<file c /etc/bind/named.conf.options>
//
// Caching only DNS Server
// https://fxdata.cloud/tutorials/configure-bind-as-a-caching-or-forwarding-dns-server-on-ubuntu-14-04
//
//acl goodclients {
//      10.10.0.9;
//      127.0.1.1;
//      127.0.0.1;
//      localhost;
//      localnets;
//};

options {
        directory "/var/cache/bind";

        // If there is a firewall between you and nameservers you want
        // to talk to, you may need to fix the firewall to allow multiple
        // ports to talk.  See http://www.kb.cert.org/vuls/id/800113
        // If your ISP provided one or more IP addresses for stable
        // nameservers, you probably want to use them as forwarders.
        // Uncomment the following block, and insert the addresses replacing
        // the all-0's placeholder.

        // forwarders {
        //      0.0.0.0;
        // };

        recursion yes;

//      allow-query {
//              goodclients;
//      };

        forwarders {
                8.8.8.8;
        };

        //forward only;

        //========================================================================
        // If BIND logs error messages about the root key being expired,
        // you will need to update your keys.  See https://www.isc.org/bind-keys
        //========================================================================
        //dnssec-validation auto;

        dnssec-enable yes;
        dnssec-validation yes;

        auth-nxdomain no;    # conform to RFC1035
        //listen-on-v6 { any; };
        listen-on-v6 { none; };

        #----------------------------------------------------------------------#

        query-source address * port 53;

        listen-on {
                127/8;
        };
};
</file>

  > service bind9 restart