Alessandro Clerici

Example BIND config files

5 min read

Warning

Modify the files in order to apply to your case! These files will not work out of the box. See the main guide for explanation and (e.g. key generating) commands.

Our setup consists of a main zone example.org, a manually mantained subzone user1.example.org, and a dynamic DNS zone dyn.example.org.

Users user1 and user2 can dynamically modify records inside the dynamic zone, each under their subdomain user[1/2].dyn.example.com.

Useruser1 set up ddclient to update an A record home.user1.dyn.example.com to their home IP address, which is also CNAMEd to home.user1.example.com.

Everything is DNSSEC-enabled.

We disabled ipv6.

BIND config

BIND config file

Our main config file looks something like this

named.conf
options {
	directory "/var/named";
	pid-file "/run/named/named.pid";
 
	listen-on	{ any; };
    // listen-on-v6 { any; };
 
	allow-recursion { none; };
	allow-transfer { none; };
	allow-update { none; };
 
	version none;
	hostname none;
	server-id none;
};
 
zone "localhost" IN {
	type master;
	file "localhost.zone";
};
 
zone "0.0.127.in-addr.arpa" IN {
	type master;
	file "127.0.0.zone";
};
 
//zone "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa" {
//	type master;
//	file "localhost.ip6.zone";
//};
 
// key for user1's dynamic updates
key "user1key" {
    algorithm hmac-sha256;
    secret "ppeue5dzUkw.........MulajQySI=";
};
 
// key for user2's dynamic updates
key "user2key" {
    algorithm hmac-sha256;
    secret "ccrhr5qmHxj.........ZhynwDlFV=";
};
 
// dynamic zone
zone "dyn.example.com" {
	type master;
	auto-dnssec maintain; // deprecated but simpler version
	inline-signing yes;
	key-directory "keys/";
	file "dyn.example.com.zone";
	update-policy {
		grant user1key wildcard *.user1.dyn.example.com ANY;
		grant user2key wildcard *.user2.dyn.example.com ANY;
	};
};
 
// user1's own zone
zone "user1.example.com" {
	type master;
	auto-dnssec maintain; // deprecated but simpler version
	inline-signing yes;
	key-directory "/srv/named/user1/keys/";
	file "/srv/named/user1/user1.example.com.zone";
};
 
// user2's own zone
zone "user2.example.com" {
	type master;
	auto-dnssec maintain; // deprecated but simpler version
	inline-signing yes;
	key-directory "/srv/named/user2/keys/";
	file "/srv/named/user2/user2.example.com.zone";
};
 
// main zone
zone "example.com" {
	type master;
	auto-dnssec maintain; // deprecated but simpler version
	inline-signing yes;
	key-directory "keys/";
	file "example.com.zone";
};
 
logging {
	channel xfer-log {
		file "/var/log/named/server.log";
		print-category yes;
		print-severity yes;
		severity info;
	};
	category xfer-in { xfer-log; };
	category xfer-out { xfer-log; };
	category notify { xfer-log; };
 
	channel query_log {
		file "/var/log/named/query.log" versions 3 size 10m;
		severity debug 3;
		print-time yes;
		print-severity yes;
		print-category yes;
	};
	category queries { query_log; };
};

Zonefiles

The domain registrar has to be set up to point ns1.example.com end ns2.example.com to the server’s IP address (NS+A records, see their docs), and it should contain a DS record containing the public key corresponding to the main zone KSK (use dnssec-dsfromkey).

Our local zonefiles will instead look something like the following.

Main zone:

/var/named/example.com.zone
$ORIGIN	example.com.
$TTL	2h
 
; DNS
@		SOA	ns1	hostmaster (
				2023151101	; Serial
				8h		    ; Refresh
				30m		    ; Retry
				1w		    ; Expire
				1h )		; Negative Cache TTL
@		NS	ns1
@		NS	ns2
ns1		A	42.42.42.42
ns2		A	42.42.42.42
 
; DNSSEC
@	DNSKEY 256 3 7	AwEAAcRfHHSvLz+NEUa.......7I/gDUr6zvF4s0yJMrv2YoXsNU= ; ZSK, ID: 01234
@	DNSKEY 257 3 7	AwEAAacg3BB/M6KbDXe.......aGuKocjR+n TSyGx6zAahwemuMr ; KSK, ID: 04321
; KSK DS record for reference:
; example.com. IN DS 54766 7 2 D501921A25AE0092AC.......A92A782D8C7029BA67B8A
 
; RECORDS
@		A	42.42.42.42
 
git			CNAME	@
info        TXT     "this is some example TXT record"
 
 
; OTHER ZONES
 
; user1
user1	    NS	ns1.user1
user1	    NS	ns2.user1
ns1.user1	A	42.42.42.42
ns2.user1	A	42.42.42.42
user1       DS 44926 7 2 186A498853ED0EE54E.......708481BA231D6CCC11B0D
 
; user2
user2	    NS	ns1.user2
user2	    NS	ns2.user2
ns1.user2	A	42.42.42.42
ns2.user2	A	42.42.42.42
user2       DS 32994 7 2 A5A0B06E98D776BBC3.......C4A98483357BB637A3768
 
; DYNAMIC
dyn         NS	ns1.dyn
dyn         NS	ns2.dyn
ns1.dyn	    A	42.42.42.42
ns2.dyn	    A	42.42.42.42
dyn         DS 22180 7 2 00D2BE8B7BA10B11CA.......26C7623A0B69B9FF55311

For user1:

/srv/named/user1/user1.example.com.zone
$ORIGIN	user1.example.com.
$TTL	2h
 
; DNS
@		SOA	ns1	hostmaster (
				2023151101	; Serial
				8h		    ; Refresh
				30m		    ; Retry
				1w		    ; Expire
				1h )		; Negative Cache TTL
@		NS	ns1
@		NS	ns2
ns1		A	42.42.42.42
ns2		A	42.42.42.42
 
; DNSSEC
@   DNSKEY 256 3 7  AwEAAcQUSthDBbzeV3F.......OlhWxgEFyUuxuI ApMuh8kZJyc= ; ZSK, ID: 11234
@   DNSKEY 257 3 7  AwEAAZVwTSB8pR8+n3n.......mGEDU24aHB zkvj84fFENt+hwJj ; KSK, ID: 14321
; KSK DS record for reference:
; user1.example.com. IN DS 44926 7 2 186A498853ED0EE54E.......708481BA231D6CCC11B0D
 
; RECORDS
@		A	    42.42.42.42
home    CNAME   home.user1.dyn.example.com.

For user2:

/srv/named/user2/user2.example.com.zone
$ORIGIN	user2.example.com.
$TTL	2h
 
; DNS
@		SOA	ns1	hostmaster (
				2023151101	; Serial
				8h		    ; Refresh
				30m		    ; Retry
				1w		    ; Expire
				1h )		; Negative Cache TTL
@		NS	ns1
@		NS	ns2
ns1		A	42.42.42.42
ns2		A	42.42.42.42
 
; DNSSEC
@   DNSKEY 256 3 7  AwEAAdkH5QoDvqxhggB.......Ibjxe8u2tyoCHt YLkcCkopCZE= ; ZSK, ID: 21234
@   DNSKEY 257 3 7  AwEAAao4cLBqQHdhLf9.......lyanhctcMI kPZGNrn0vxtkvg4T ; KSK, ID: 24321
; KSK DS record for reference:
; user2.example.com. IN DS 32994 7 2 A5A0B06E98D776BBC3.......C4A98483357BB637A3768
 
; RECORDS
@		A	    42.42.42.42

For dynamic zone (this is only the initial zonefile, it will be overwritten by the server when dynamic changes are performed - commenting is useless for this reason):

/var/named/dyn.example.com.zone
$ORIGIN	dyn.example.com.
$TTL	2h
 
@		SOA	ns1	hostmaster (
				2023151101
				8h
				30m
				1w
				1h )
@		NS	ns1
@		NS	ns2
ns1		A	42.42.42.42
ns2		A	42.42.42.42
 
@   DNSKEY 256 3 7  AwEAAbxFBaMjSI0asdm.......zAqrVViCHGdvHe Du/wTG6Qbt8= ; ZSK, ID: 91234
@   DNSKEY 257 3 7  AwEAAcQPOmgD/V4qWHH.......Exj2ymiVoS Yg7Q5qnGNPWC1B+P ; KSK, ID: 94321
; KSK DS record for reference:
; dyn.example.com. IN DS 22180 7 2 00D2BE8B7BA10B11CA.......26C7623A0B69B9FF55311

ddclient config

User user1 copies their TSIG key “user1key” in /etc/ddclient/user1key.key, then they modify /etc/ddclient/ddclient.conf to match the following:

/etc/ddclient/ddclient.conf
use=web, web=ipinfo.io/ip
protocol=nsupdate
server=ns1.dyn.example.com
password=/etc/ddclient/user1key.key
zone=dyn.example.com
home.user1.dyn.example.com

Other files

Besides the mentioned files, we also have

  • private keys, readable by user named and in directories writable by user named, in /var/named/keys/, /srv/named/user1/keys/, /srv/named/user2/keys/ and in user1’s home server in /etc/ddclient/user1key.key (the last one has nothing to do with named).
  • public keys which could technically be deleted but it’s best to keep for reference
  • accurate directory permissions for /var/named (only named for read and write), /srv/named/user1/ (named for read and user1 for read and write) and the same for /srv/named/user2/, /etc/ddclient/ on user1’s home machine (only root has read and write, especially to user1key.key)

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