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losnir/README.md

Created December 28, 2021 01:05
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recursive DNS resolver using unbound in K8S
Raw
README.md

This gist is how I personally deploy an arm64 version of unbound (for running on Raspberry Pi) configured as a recursive DNS resolver.

Use case is setting this up as the upstream resolver in PiHole (also running in K8S) in order to eliminate the need of a 3rd-party resolver (i.e. Cloudflare, Quad9), potentially avoiding DNS spoofing / poisoning / etc.

Service is exposed with a ClusterIP under 10.43.0.53 listening to both TCP/UDP on port 53.

TODO / Considerations:

  • This still does not hide your DNS traffic from your ISP since root nameservers do not use DoH/DoT. Ultimately, this should run somewhere in the cloud (for example AWS EC2/ECS) and configured in DoH/DoT mode. This is also a fantastic opportunity to use ZeroTier for tying it all together to your local LAN without exposing your cloud resources to the public, while increasing security (ZT is encrypted).

  • Maybe setup an init container to fetch the most up-to-date definition of the root.hints file, instead of hard-coding it into the ConfigMap. This has the downside of updating your root nameserver without your discretion, which kind of defeats the purpose. Thoughts?

Raw
unbound.configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
namespace: unbound
name: unbound-config
data:
unbound.conf: |
server:
# Enable or disable whether the unbound server forks into the background
# as a daemon. Default is yes.
do-daemonize: no
# If given, after binding the port the user privileges are dropped.
# Default is "unbound". If you give username: "" no user change is performed.
username: "unbound"
# No need to chroot as this container has been stripped of all other binaries.
chroot: ""
# If "" is given, logging goes to stderr, or nowhere once daemonized.
logfile: ""
# The process id is written to the file. Not required since we are running
# in a container with one process.
pidfile: ""
# The verbosity number, level 0 means no verbosity, only errors.
# Level 1 gives operational information.
# Level 2 gives detailed operational information.
# Level 3 gives query level information, output per query.
# Level 4 gives algorithm level information.
# Level 5 logs client identification for cache misses.
# Default is level 1. The verbosity can also be increased from the commandline.
verbosity: 1
# Listen on all ipv4 interfaces, answer queries from the local subnet.
interface: 0.0.0.0
# The port number, default 53, on which the server responds to queries.
port: 53
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: /etc/unbound/root.hints
# File with trust anchor for one zone, which is tracked with RFC5011 probes.
# The probes are several times per month, thus the machine must be online frequently.
# The initial file can be one with contents as described in trust-anchor-file.
# The file is written to when the anchor is updated, so the unbound user must
# have write permission.
auto-trust-anchor-file: /etc/unbound/root.key
# 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.
# Suggested by the unbound man page to reduce fragmentation reassembly problems
edns-buffer-size: 1472
# 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
# (requires CAP_NET_ADMIN or privileged)
so-rcvbuf: 1m
# The netblock is given as an IP4 or IP6 address with /size appended for a
# classless network block. The action can be deny, refuse, allow or allow_snoop.
access-control: 127.0.0.1/32 allow
access-control: 192.168.0.0/16 allow
access-control: 172.16.0.0/12 allow
access-control: 10.0.0.0/8 allow
# 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
root.hints: |
; This file holds the information on root name servers needed to
; initialize cache of Internet domain name servers
; (e.g. reference this file in the "cache . <file>"
; configuration file of BIND domain name servers).
;
; This file is made available by InterNIC
; under anonymous FTP as
; file /domain/named.cache
; on server FTP.INTERNIC.NET
; -OR- RS.INTERNIC.NET
;
; last update: December 16, 2021
; related version of root zone: 2021121601
;
; FORMERLY NS.INTERNIC.NET
;
. 3600000 NS A.ROOT-SERVERS.NET.
A.ROOT-SERVERS.NET. 3600000 A 198.41.0.4
A.ROOT-SERVERS.NET. 3600000 AAAA 2001:503:ba3e::2:30
;
; FORMERLY NS1.ISI.EDU
;
. 3600000 NS B.ROOT-SERVERS.NET.
B.ROOT-SERVERS.NET. 3600000 A 199.9.14.201
B.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:200::b
;
; FORMERLY C.PSI.NET
;
. 3600000 NS C.ROOT-SERVERS.NET.
C.ROOT-SERVERS.NET. 3600000 A 192.33.4.12
C.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:2::c
;
; FORMERLY TERP.UMD.EDU
;
. 3600000 NS D.ROOT-SERVERS.NET.
D.ROOT-SERVERS.NET. 3600000 A 199.7.91.13
D.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:2d::d
;
; FORMERLY NS.NASA.GOV
;
. 3600000 NS E.ROOT-SERVERS.NET.
E.ROOT-SERVERS.NET. 3600000 A 192.203.230.10
E.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:a8::e
;
; FORMERLY NS.ISC.ORG
;
. 3600000 NS F.ROOT-SERVERS.NET.
F.ROOT-SERVERS.NET. 3600000 A 192.5.5.241
F.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:2f::f
;
; FORMERLY NS.NIC.DDN.MIL
;
. 3600000 NS G.ROOT-SERVERS.NET.
G.ROOT-SERVERS.NET. 3600000 A 192.112.36.4
G.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:12::d0d
;
; FORMERLY AOS.ARL.ARMY.MIL
;
. 3600000 NS H.ROOT-SERVERS.NET.
H.ROOT-SERVERS.NET. 3600000 A 198.97.190.53
H.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:1::53
;
; FORMERLY NIC.NORDU.NET
;
. 3600000 NS I.ROOT-SERVERS.NET.
I.ROOT-SERVERS.NET. 3600000 A 192.36.148.17
I.ROOT-SERVERS.NET. 3600000 AAAA 2001:7fe::53
;
; OPERATED BY VERISIGN, INC.
;
. 3600000 NS J.ROOT-SERVERS.NET.
J.ROOT-SERVERS.NET. 3600000 A 192.58.128.30
J.ROOT-SERVERS.NET. 3600000 AAAA 2001:503:c27::2:30
;
; OPERATED BY RIPE NCC
;
. 3600000 NS K.ROOT-SERVERS.NET.
K.ROOT-SERVERS.NET. 3600000 A 193.0.14.129
K.ROOT-SERVERS.NET. 3600000 AAAA 2001:7fd::1
;
; OPERATED BY ICANN
;
. 3600000 NS L.ROOT-SERVERS.NET.
L.ROOT-SERVERS.NET. 3600000 A 199.7.83.42
L.ROOT-SERVERS.NET. 3600000 AAAA 2001:500:9f::42
;
; OPERATED BY WIDE
;
. 3600000 NS M.ROOT-SERVERS.NET.
M.ROOT-SERVERS.NET. 3600000 A 202.12.27.33
M.ROOT-SERVERS.NET. 3600000 AAAA 2001:dc3::35
; End of file
Raw
unbound.svc.yaml
apiVersion: v1
kind: Service
metadata:
namespace: unbound
name: unbound
spec:
clusterIP: 10.43.0.53
selector:
app: unbound
ports:
- name: dns
protocol: UDP
port: 53
targetPort: 53
- name: dns-tcp
protocol: TCP
port: 53
targetPort: 53
Raw
unbound.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
namespace: unbound
labels:
app: unbound
name: unbound
spec:
replicas: 1
selector:
matchLabels:
app: unbound
strategy: {}
template:
metadata:
labels:
app: unbound
spec:
containers:
- name: unbound
image: klutchell/unbound
volumeMounts:
- name: config-volume
mountPath: "/etc/unbound/unbound.conf"
subPath: unbound.conf
- name: config-volume
mountPath: "/etc/unbound/root.hints"
subPath: root.hints
securityContext:
privileged: true
resources: {}
volumes:
- name: config-volume
configMap:
name: unbound-config
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