Pejman Moghadam / Slackware

Slackware 13.37 - Dynamic DNS using Bind and ISC DHCP server

Public domain

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Create a dnssec key

# dnssec-keygen -a hmac-md5 -b 128 -n USER dhcpupdate
Kdhcpupdate.+157+30215

# ls
Kdhcpupdate.+157+30215.key  Kdhcpupdate.+157+30215.private

# cat Kdhcpupdate.+157+30215.key
dhcpupdate. IN KEY 0 3 157 EFRHY4Vd4rOqbwphd5yGNA==

# cat Kdhcpupdate.+157+30215.private
Private-key-format: v1.2
Algorithm: 157 (HMAC_MD5)
Key: EFRHY4Vd4rOqbwphd5yGNA==
Bits: AAA=

if you run dnssec-keygen on virtual machines and it hangs for a while, add '-r /dev/urandom' option to dnssec-keygen command line.

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/etc/named.conf

options {
        directory "/var/named";
};

zone "." IN {
        type hint;
        file "caching-example/named.root";
};

zone "localhost" IN {
        type master;
        file "caching-example/localhost.zone";
        allow-update { none; };
};

zone "0.0.127.in-addr.arpa" IN {
        type master;
        file "caching-example/named.local";
        allow-update { none; };
};

key dhcpupdate {
        algorithm hmac-md5;
        secret "EFRHY4Vd4rOqbwphd5yGNA==";
};

zone "example.com" {
        type master;
        file "example.com.fwd";
        allow-update { key dhcpupdate; };
};

zone "1.16.172.in-addr.arpa" {
        type master;
        file "example.com.rev";
        allow-update { key dhcpupdate; };
};

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/var/named/example.com.fwd

$TTL 1D
$ORIGIN example.com.
@ SOA ns hostmaster (
        2012150700  ; sn
        1H          ; ref
        10M         ; ret
        1W          ; exp
        3H )        ; min
     NS ns
ns   A  172.16.1.2

---

/var/named/example.com.rev

$TTL 1D
$ORIGIN 1.16.172.in-addr.arpa.
@ SOA ns.example.com. hostmaster.example.com. (
        2012071500  ; sn
        1H          ; ref
        10M         ; ret
        1W          ; exp
        3H )        ; min
     NS  ns1.example.com.
2    PTR ns1.example.com.

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Restart bind

chmod  +x /etc/rc.d/rc.bind
/etc/rc.d/rc.bind restart

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Test with nsupdate

# nsupdate
> server 172.16.1.2
> key dhcpupdate EFRHY4Vd4rOqbwphd5yGNA==
> zone example.com
> update add laptop.example.com. 600 IN A 172.16.1.50
> send
> zone 1.16.172.in-addr.arpa
> update add 50.1.16.172.in-addr.arpa 600 IN PTR laptop.example.com.
> send
> quit

# dig +short @172.16.1.2 laptop.example.com
172.16.1.50

# dig +short @172.16.1.2 -x 172.16.1.50
laptop.example.com.


# nsupdate
> server 172.16.1.2
> key dhcpupdate EFRHY4Vd4rOqbwphd5yGNA==
> zone example.com
> update delete laptop.example.com.
> send
> zone 1.16.172.in-addr.arpa
> update delete 50.1.16.172.in-addr.arpa 
> send
> quit

---

Note

if your named server refused to start with the following warning logs:

journal rollforward failed: journal out of sync with zone

delete .jnl files and restart bind:

cd /var/named
rm *.jnl
/etc/rc.d/rc.bind restart

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/etc/dhcpd.conf

ddns-update-style interim;
update-static-leases on;

default-lease-time 300;
max-lease-time 3600;

key dhcpupdate {
  algorithm hmac-md5;
  secret EFRHY4Vd4rOqbwphd5yGNA==;
}

zone example.com. {
        primary 172.16.1.2;
        key dhcpupdate;
}

zone 1.16.172.in-addr.arpa. {
        primary 172.16.1.2;
        key dhcpupdate;
}

subnet 172.16.1.0 netmask 255.255.255.0 {
        option routers 172.16.1.2;
        option subnet-mask 255.255.255.0;
        option domain-name-servers 37.152.160.18, 8.8.8.8;
        range 172.16.1.100 172.16.1.200;
        ddns-domainname "example.com";
        ddns-hostname = concat(binary-to-ascii(10, 8, "-", leased-address), ".dynamic");
        #ddns-hostname = binary-to-ascii (16, 8, "-", substring (hardware, 1, 6));

        host webserver {
                hardware ethernet 3e:4b:37:00:82:00;
                fixed-address 172.16.1.50;
                ddns-hostname "www";
                ddns-domainname "example.com";
        }
}

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Start dhcp server

touch /var/state/dhcp/dhcpd.leases
dhcpd

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Test dynamic lease

# dig +short @172.16.1.2 172-16-1-100.dynamic.example.com
172.16.1.100

# dig +short @172.16.1.2 -x 172.16.1.100
172-16-1-100.dynamic.example.com.

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Test static lease

# dig +short @172.16.1.2  www.example.com
172.16.1.50
# dig +short @172.16.1.2  -x 172.16.1.50
www.example.com.

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Dump journal files to zone files (freeze/unfreeze) - dynamic update temporarily disabled

rndc freeze example.com
rndc freeze 1.16.172.in-addr.arpa
rndc thaw example.com
rndc thaw 1.16.172.in-addr.arpa

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Important manuals

man dhcpd.conf
man dhcp-eval

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BY: Pejman Moghadam
TAG: dhcpd, bind, ddns, dns
DATE: 2012-07-15 14:04:49

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Pejman Moghadam / Slackware [ TXT ]