Category: Dev Ops

Create a new folder in new location, for example pihole-db.

mkdir pihole-db
# make sure folder has this permission
chmod 775 pihole-db
# change user/group to pihole on this folder
chown pihole:pihole pihole-db

We will be creating symlink (symbolic link) by copying database to pihole-db.

https://unix.stackexchange.com/questions/218557/how-to-change-ownership-of-symbolic-links

# Pihole-FTL.db
# stop Pihole service
sudo service pihole-FTL stop
cp /etc/pihole/pihole-FTL.db /srv/pihole-data
chown pihole:pihole pihole-FTL.db
# rm /etc/pihole/pihole-FTL.db
# create link in /etc/pihole
ln -s /srv/pihole-db/pihole-FTL.db pihole-FTL.db
# change owner/group of symlinks
sudo chown -h pihole:pihole pihole-FTL.db

# start the service
sudo service pihole-FTL start
# check service status
# systemctl status pihole-FTL

Open browser, navigate to a site and see if pihole-FTL works.

Pihole-FTL started working. Let’s move others;

# gravity.db
sudo service pihole-FTL stop
cp /etc/pihole/gravity.db /srv/pihole-db
ls -l /srv/pihole-db
chown pihole:pihole /srv/pihole-db/gravity.db
rm /etc/pihole/gravity.db
# create symlink in /etc/pihole
ln -s /srv/pihole-db/gravity.db gravity.db
# change owner/group of symlinks
sudo chown -h pihole:pihole gravity.db

# verify
sudo service pihole-FTL start

# macvendor.db
sudo service pihole-FTL stop
cp /etc/pihole/macvendor.db /srv/pihole-db
ls -l /srv/pihole-db

chown pihole:pihole /srv/pihole-db/macvendor.db
rm /etc/pihole/macvendor.db
# create symlink in /etc/pihole
ln -s /srv/pihole-db/macvendor.db macvendor.db
sudo chown -h pihole:pihole macvendor.db
# verify
sudo service pihole-FTL start

# list.1.raw.githubusercontent.com.domains
sudo service pihole-FTL stop
cp /etc/pihole/list.1.raw.githubusercontent.com.domains /srv/pihole-db
ls -l /srv/pihole-db

rm /etc/pihole/list.1.raw.githubusercontent.com.domains
# create symlink in /etc/pihole
ln -s /srv/pihole-db/list.1.raw.githubusercontent.com.domains list.1.raw.githubusercontent.com.domains
# verify
sudo service pihole-FTL start

Make sure you have changed owner and group of sym(Symbolic) links of these databases.

https://www.freecodecamp.org/news/symlink-tutorial-in-linux-how-to-create-and-remove-a-symbolic-link/

sudo chown -h pihole:pihole pihole-FTL.db
sudo chown -h pihole:pihole macvendor.db
sudo chown -h pihole:pihole gravity.db

Make sure you can see these permissions;

To reset, run this command;

chmod 664 gravity.db

Here is your modified file system;

To rebuild gravity database, run this and see the time stamp;

pihole -g

https://discourse.pi-hole.net/t/gravity-database/46182

For macvendor database refer to this;

Resources

https://www.cyberciti.biz/faq/linux-log-files-location-and-how-do-i-view-logs-files/

Install this;

sudo apt install unbound

run this command;

nano /etc/unbound/unbound.conf.d/pi-hole.conf

copy and paste this from pi-hole site;

server:
    # If no logfile is specified, syslog is used
    # logfile: "/var/log/unbound/unbound.log"
    verbosity: 0

    interface: 127.0.0.1
    port: 5335
    do-ip4: yes
    do-udp: yes
    do-tcp: yes

    # May be set to yes if you have IPv6 connectivity
    do-ip6: no

    # You want to leave this to no unless you have *native* IPv6. With 6to4 and
    # Terredo tunnels your web browser should favor IPv4 for the same reasons
    prefer-ip6: no

    # Use this only when you downloaded the list of primary root servers!
    # If you use the default dns-root-data package, unbound will find it automatically
    #root-hints: "/var/lib/unbound/root.hints"

    # Trust glue only if it is within the server's authority
    harden-glue: yes

    # Require DNSSEC data for trust-anchored zones, if such data is absent, the zone becomes BOGUS
    harden-dnssec-stripped: yes

    # Don't use Capitalization randomization as it known to cause DNSSEC issues sometimes
    # see https://discourse.pi-hole.net/t/unbound-stubby-or-dnscrypt-proxy/9378 for further details
    use-caps-for-id: no

    # Reduce EDNS reassembly buffer size.
    # IP fragmentation is unreliable on the Internet today, and can cause
    # transmission failures when large DNS messages are sent via UDP. Even
    # when fragmentation does work, it may not be secure; it is theoretically
    # possible to spoof parts of a fragmented DNS message, without easy
    # detection at the receiving end. Recently, there was an excellent study
    # >>> Defragmenting DNS - Determining the optimal maximum UDP response size for DNS <<<
    # by Axel Koolhaas, and Tjeerd Slokker (https://indico.dns-oarc.net/event/36/contributions/776/)
    # in collaboration with NLnet Labs explored DNS using real world data from the
    # the RIPE Atlas probes and the researchers suggested different values for
    # IPv4 and IPv6 and in different scenarios. They advise that servers should
    # be configured to limit DNS messages sent over UDP to a size that will not
    # trigger fragmentation on typical network links. DNS servers can switch
    # from UDP to TCP when a DNS response is too big to fit in this limited
    # buffer size. This value has also been suggested in DNS Flag Day 2020.
    edns-buffer-size: 1232

    # Perform prefetching of close to expired message cache entries
    # This only applies to domains that have been frequently queried
    prefetch: yes

    # One thread should be sufficient, can be increased on beefy machines. In reality for most users running on small networks or on a single machine, it should be unnecessary to seek performance enhancement by increasing num-threads above 1.
    num-threads: 1

    # Ensure kernel buffer is large enough to not lose messages in traffic spikes
    so-rcvbuf: 1m

    # Ensure privacy of local IP ranges
    private-address: 192.168.0.0/16
    private-address: 169.254.0.0/16
    private-address: 172.16.0.0/12
    private-address: 10.0.0.0/8
    private-address: fd00::/8
    private-address: fe80::/10

save file CTRL+X.

Start local recursive server and test that it’s operational;

sudo service unbound restart
dig pi-hole.net @127.0.0.1 -p 5335

The first query may be quite slow, but subsequent queries, also to other domains under the same TLD, should be fairly quick.

You should also consider adding

edns-packet-max=1232

to a config file like /etc/dnsmasq.d/99-edns.conf to signal FTL to adhere to this limit.

Test Valiation

You can test DNSSEC validation using

dig sigfail.verteiltesysteme.net @127.0.0.1 -p 5335
dig sigok.verteiltesysteme.net @127.0.0.1 -p 5335

The first command should give a status report of SERVFAIL and no IP address. The second should give NOERROR plus an IP address.

Configure Pi-hole

Finally, configure Pi-hole to use your recursive DNS server by specifying 127.0.0.1#5335 as the Custom DNS (IPv4):

Make sure this is the only record you have. For further info, refer to this;

https://docs.pi-hole.net/guides/dns/unbound/