All Pages > Services > DNS > Configuration

Forwarder setup

Configuration of common resolver softwares to forward DNS queries for .dn42 (and reverse DNS) IPv4 and IPv6 anycast services.

You can use any *.recursive-servers.dn42 (where * is a letter) for resolving .dn42 domains. The current list is available at the DN42 registry or through querying SRV records of recursive-servers.dn42:

drill -D SRV _dns._udp.recursive-servers.dn42. @172.20.0.53

Two independent anycast services are also provided:

All the examples here list 172.20.0.53/fd42:d42:d42:54::1, but users are encouraged to configure multiple services from *.recursive-servers.dn42 for redundancy.

Note on ICVPN Zones

DN42 is interconnected with the Inter City VPN or in short "ICVPN". The registry of the ICVPN includes all the DNS information such as the Top level domains (TLDs) used inside ICVPN and the reverse DNS for the IP ranges of the ICVPN. Additionally, it includes the TLDs of some other networks that are interconnected with dn42 and share some of the IP space of ICVPN. The ICVPN repository includes a handy script to automatically generate all the required zones.

BIND

If you already run a local DNS server, you can tell it to query the dn42 anycast servers for the relevant domains by adding the following to /etc/bind/named.conf.local

zone "dn42" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};
zone "20.172.in-addr.arpa" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};
zone "21.172.in-addr.arpa" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};
zone "22.172.in-addr.arpa" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};
zone "23.172.in-addr.arpa" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};
zone "10.in-addr.arpa" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};
zone "d.f.ip6.arpa" {
  type forward;
  forwarders { 172.20.0.53; fd42:d42:d42:54::1; };
};

# for reverse dns to work the following option must be set:
options {
  # [...]

  # disable the integrated handling of RFC1918 and non-assigned IPv6 space reverse dns
  empty-zones-enable no;

  # [...]
};

Note: With DNSSEC enabled, bind might refuse to accept query results from the dn42 zone: validating dn42/SOA: got insecure response; parent indicates it should be secure.

To disable DNSSEC validation only for certain TLDs include the following in the options section:

options {
  # [...]

  validate-except {
    "dn42";
    "20.172.in-addr.arpa";
    "21.172.in-addr.arpa";
    "22.172.in-addr.arpa";
    "23.172.in-addr.arpa";
    "10.in-addr.arpa";
    "d.f.ip6.arpa";
  };

  # [...]
};

dnsmasq

If you are running dnsmasq under openwrt, you just have to add

config dnsmasq
        option boguspriv '0'
        option rebind_protection '1'
        list rebind_domain 'dn42'
        list server '/dn42/172.20.0.53'
        list server '/20.172.in-addr.arpa/172.20.0.53'
        list server '/21.172.in-addr.arpa/172.20.0.53'
        list server '/22.172.in-addr.arpa/172.20.0.53'
        list server '/23.172.in-addr.arpa/172.20.0.53'
        list server '/10.in-addr.arpa/172.20.0.53'
        list server '/d.f.ip6.arpa/fd42:d42:d42:54::1'

to /etc/config/dhcp and run /etc/init.d/dnsmasq restart. After that you are able to resolve .dn42 with the anycast DNS-Server, while your normal requests go to your standard DNS-resolver.

Attention: If you go with the default config you'll have to disable "boguspriv" in the first dnsmasq config section.

For normal dnsmasq use

server=/dn42/172.20.0.53
server=/20.172.in-addr.arpa/172.20.0.53
server=/21.172.in-addr.arpa/172.20.0.53
server=/22.172.in-addr.arpa/172.20.0.53
server=/23.172.in-addr.arpa/172.20.0.53
server=/10.in-addr.arpa/172.20.0.53
server=/d.f.ip6.arpa/fd42:d42:d42:54::1

in dnsmasq.conf.

PowerDNS recursor

Add this to /etc/powerdns/recursor.conf (at least in Debian and CentOS).

dont-query=127.0.0.0/8, 192.168.0.0/16, ::1/128, fe80::/10
forward-zones-recurse=dn42=172.20.0.53
forward-zones-recurse+=20.172.in-addr.arpa=172.20.0.53
forward-zones-recurse+=21.172.in-addr.arpa=172.20.0.53
forward-zones-recurse+=22.172.in-addr.arpa=172.20.0.53
forward-zones-recurse+=23.172.in-addr.arpa=172.20.0.53
forward-zones-recurse+=10.in-addr.arpa=172.20.0.53
forward-zones-recurse+=d.f.ip6.arpa=172.20.0.53

MaraDNS

Put this in your mararc:

ipv4_alias["dn42_root"] = "172.20.0.53"
root_servers["dn42."] = "dn42_root"
root_servers["20.172.in-addr.arpa."] = "dn42_root"
root_servers["21.172.in-addr.arpa."] = "dn42_root"
root_servers["22.172.in-addr.arpa."] = "dn42_root"
root_servers["23.172.in-addr.arpa."] = "dn42_root"
root_servers["10.in-addr.arpa."] = "dn42_root"

Unbound

Make sure to disable auto-trust-anchor-file and manually configure trust-anchor-file to point to a file with DNSKEY records for dn42.

server:
      local-zone: "20.172.in-addr.arpa." nodefault
      local-zone: "21.172.in-addr.arpa." nodefault
      local-zone: "22.172.in-addr.arpa." nodefault
      local-zone: "23.172.in-addr.arpa." nodefault
      local-zone: "10.in-addr.arpa." nodefault
      local-zone: "d.f.ip6.arpa." nodefault

forward-zone: 
      name: "dn42"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

forward-zone: 
      name: "20.172.in-addr.arpa"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

forward-zone: 
      name: "21.172.in-addr.arpa"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

forward-zone: 
      name: "22.172.in-addr.arpa"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

forward-zone: 
      name: "23.172.in-addr.arpa"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

forward-zone: 
      name: "10.in-addr.arpa"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

forward-zone:
      name: "d.f.ip6.arpa"
      forward-addr: fd42:d42:d42:54::1
      forward-addr: 172.20.0.53

JunOS (SRX 12.1X46)

Should also work in 12.1X44 and 12.1X45. After making the changes below you may need to run:

restart named-service

Config (vlan.0 is presumed to be your LAN/Trust interface)

system {
   services {
      dns {
         dns-proxy {
            interface {
               vlan.0;
            }
        default-domain dn42 {
           forwarders {
              172.20.0.53;
	      fd42:d42:d42:54::1;
           }
        }
        default-domain 20.172.in-addr.arpa {
               forwarders {
                  172.20.0.53;
		  fd42:d42:d42:54::1;
               }
            }
        default-domain 21.172.in-addr.arpa {
               forwarders {
                  172.20.0.53;
		  fd42:d42:d42:54::1;
               }
            }
        default-domain 22.172.in-addr.arpa {
               forwarders {
                  172.20.0.53;
		  fd42:d42:d42:54::1;
               }
            }
            default-domain 23.172.in-addr.arpa {
               forwarders {
                  172.20.0.53;
                  fd42:d42:d42:54::1;
               }
            }
            default-domain 10.in-addr.arpa {
               forwarders {
                  172.20.0.53;
                  fd42:d42:d42:54::1;
               }
            }
         }
      }
   }
}

MS DNS

Add a "Conditional Forward" (de: "Bedingte Weiterleitung") for each of "dn42", "20.172.in-addr.arpa", "21.172.in-addr.arpa", "22.172.in-addr.arpa", "23.172.in-addr.arpa", "10.in-addr.arpa" using 172.20.0.53 as forwarder. Ignore the error message that the server is not authoritative.

systemd-resolved

If you are using systemd-networkd and systemd-resolved in a version later then v240 you can set up split DNS by adding the dn42 anycast servers to a interface:

[Match]
Name=dummy0

[Network]
 # don't try to resolve normal internet domains with theses resolvers
DNSDefaultRoute=false
# configure dn42 anycast servers
DNS=fd42:d42:d42:54::1
DNS=172.23.0.53
DNS=fd42:d42:d42:53::1
DNS=172.20.0.53

# configure all relevant dn42 domains as route-only domains
Domains=~dn42
Domains=~20.172.in-addr.arpa
Domains=~21.172.in-addr.arpa
Domains=~22.172.in-addr.arpa
Domains=~23.172.in-addr.arpa
Domains=~10.in-addr.arpa
Domains=~d.f.ip6.arpa

Resolver setup

Configuration of common resolver softwares to do full recursion DNS queries for .dn42 (and reverse DNS) IPv4 and IPv6 anycast services.

You can use any *.delegation-servers.dn42 (where * is a letter) as an authoritative server for .dn42 TLD. The current list is available at the DN42 registry or through querying NS records of dn42.:

dig dn42. NS @172.20.0.53

Current list of delegation servers (as of 03/04/2022):

All the examples here list 172.20.129.1/fd42:4242:2601:ac53::1, but users are encouraged to configure multiple services from *.delegation-servers.dn42 for redundancy.

Dnssec

All delegation servers have DNSSEC support and all record are signed, for more information about DNSSEC visit New-DNS#dnssec.

Following is a list of links to the DS record for TLD and reverse zone, to configure the key file, extract the value of ds-rdata and format it as follows, you must add all ds-rdata to the key file for dnssec to work. P.S. each ds-rdata or DS record should contain 4 numbers.

This is an example for dn42. and (fake) ds-rdata of 1 2 3 456

dn42.	86400	IN	DS	1 2 3 456

This is an example for 172.20.0.0/16 and (fake) ds-rdata of 1 2 3 456

20.172.in-addr.arpa.	86400	IN	DS	1 2 3 456

This is an example for fd00::/8 and (fake) ds-rdata of 1 2 3 456

d.f.ip6.arpa.	86400	IN	DS	1 2 3 456

DN42 DS record

dn42. TLD

172.20.0.0/16 range

172.21.0.0/16 range

172.22.0.0/16 range

172.23.0.0/16 range

fd00::/8 range

Non DN42 DS record

172.31.0.0/16 (chaosvpn) range

10.0.0.0/8 (Freifunk) range

Unbound

trust-anchor-file: <path to key file>

server:
local-zone: "dn42" typetransparent
local-zone: "20.172.in-addr.arpa" typetransparent
local-zone: "21.172.in-addr.arpa" typetransparent
local-zone: "22.172.in-addr.arpa" typetransparent
local-zone: "23.172.in-addr.arpa" typetransparent
local-zone: "d.f.ip6.arpa" typetransparent

private-domain: "dn42"
private-domain: "20.172.in-addr.arpa"
private-domain: "21.172.in-addr.arpa"
private-domain: "22.172.in-addr.arpa"
private-domain: "23.172.in-addr.arpa"
private-domain: "d.f.ip6.arpa"

stub-zone:
	name: "dn42"
	stub-addr: fd42:4242:2601:ac53::1
	stub-addr: 172.20.129.1

stub-zone:
	name: "20.172.in-addr.arpa"
	stub-addr: fd42:4242:2601:ac53::1
	stub-addr: 172.20.129.1

stub-zone:
	name: "21.172.in-addr.arpa"
	stub-addr: fd42:4242:2601:ac53::1
	stub-addr: 172.20.129.1

stub-zone:
	name: "22.172.in-addr.arpa"
	stub-addr: fd42:4242:2601:ac53::1
	stub-addr: 172.20.129.1

stub-zone:
	name: "23.172.in-addr.arpa"
	stub-addr: fd42:4242:2601:ac53::1
	stub-addr: 172.20.129.1

stub-zone:
	name: "d.f.ip6.arpa"
	stub-addr: fd42:4242:2601:ac53::1
	stub-addr: 172.20.129.1