dnssec-reverb

Shell script based DNSSEC key management tool

I was looking for something that would take care of the rotation of my DNSSEC keys that wouldn't require many dependencies, was simple to manage and that I could actually trust - easily auditable. I found an unmaintained script called dnsseczonetool from @kfujiwara and refactor it to fit my needs. It is used and tested on OpenBSD but should work pretty much anywhere with the proper paths.

Reverb is straightforward and couldn't be more trustable/easy to audit. Enjoy!

Release notes

• CAUTION the latest release changed the serial special tag from '_SERIAL_' to '00001111' to ensure named/nsd compatibility. Update your master zone.

Features

• Supports nsd and bind servers
• Supports ldns and bind's dnssec tools
• Should run on any unix-like systems™
• Don't trust me, audit the code!™
• KISS®
• auto increment of the serial (date format)

Requirements

• nsd or bind
• ldns from NLnet labs or bind's DNSSEC tools
• standard unix tools such as sed & awk

Installation

1. Copy dnssec-reverb in a directory in your $PATH.

   $ sudo cp dnssec-reverb /usr/local/sbin/

2. Create a configuration file. The config file will be searched in the following order 1) by looking at the $DNSSEC_REVERB_CONF environment variable, 2) within the same directory than the script (dirname $0), 3) within /etc/ and finally 4) within /usr/local/etc/. At the very least it must specify the master zone file directory using the MASTERDIR variable. Optionnaly, specific domain parameters can be set - see the configuration section.

   echo MASTERDIR="/var/nsd/zones/master" >> /etc/dnssec-reverb.conf
   echo ZSK_PARAM_example.org="-a RSASHA1-NSEC3-SHA1" >> /etc/dnssec-reverb.conf
   

3. Prepare the traditional zone files and set the serial to this special tag: 00001111. We use a number to keep named checkzone compatibility. The file name should be equal to the zone name.

   $ grep serial example.org
   @ IN SOA ns1.example.org. dnsmaster.example.org. (
   00001111   ; serial
   1h         ; refresh (1 hours)
   1h         ; retry (1 hour)
   5w         ; expire (4 weeks)
   30m        ; minimum (30 minutes)
   

4. Edit nsd.conf to load the signed zone file:

   zone "example.org" {
       type master;
       file "/var/nsd/zones/master/example.org.signed";
   }
   

5. Generate first key and sign zone:

   dnssec-reverb keygen example.org
   dnssec-reverb sign example.org
   

You can validate your DNSSEC setup using this web app: http://dnsviz.net/d/mantor.org/dnssec/

Configuration

To override the default configuration (as describe below in parentheses), simply edit dnssec-reverb.conf.

Paths | default value:

• MASTERDIR: Master zone file directory | mandatory - no default
• DBDIR: directory used to store state and data | $MASTERDIR/dnssec-reverb-db
• keygen: ldns-keygen path | $(which ldns-keygen)
• signzone: ldns-signzone path | $(which ldns-signzone)
• key2ds: ldns-key2ds path | $(which ldns-key2ds)
• checkzone: nsd-checkzone path | $(which nsd-checkzone)
• control: nsd-control path | $(which nsd-control)
• RELOAD_COMMAND: reload command | (echo -n 'reload is '; $control reload) && (echo -n 'notify is '; $control notify)

Params - default value:

• KSK_PARAM: keygen's options for KSK | '-a ECDSAP256SHA256 -k'
• ZSK_PARAM: keygen's options for ZSK | '-a ECDSAP256SHA256'
• SIGN_PARAM: signzone options | '-n' (NSEC3)
• DS_PARAM: key2ds or dsfromkey options | '-2' (SHA256)

Signatures expiration:

• EXPIRE_DAYS: used to calculate the expiration date of the signatures to this date. Defaults to 33.

The previous configuration set can be overridden by zone by simply adding "_$zone" at the end of the variable. For example: ZSK_PARAM_example.org="-a RSASHA1-NSEC3-SHA1" to change the cipher for example.org's keys only. All zone name must be lowercase. Zone whose name contains '.' and '-' characters are replaced by '_'.

Usage

$ dnssec-reverb
usage: dnssec-reverb keygen <zone>
       dnssec-reverb rmkeys <zone>
       dnssec-reverb [-s] ksk-add <zone>
       dnssec-reverb [-s] ksk-roll <zone>
       dnssec-reverb [-s] zsk-add <zone>
       dnssec-reverb [-s] zsk-roll <zone>
       dnssec-reverb [-s] zsk-rmold <zone>
       dnssec-reverb sign <zone>
       dnssec-reverb status <zone>

Initial setup - assuming your zone has no DNSSEC keys published

1. Generate KSK and ZSK.

   dnssec-reverb keygen example.org

2. Retrieve your fresh KSK's digest and setup the DS at your registrar.

   dnssec-reverb status example.org

3. Sign zone using keys generated in step #1.

   dnssec-reverb sign example.org

Rollover of the KSK

Manual

1. Add and publish an additional but not valid/signed KSK. After this operation you will have two KSK, one active/signed by your registrar and a new one not active/signed.

   dnssec-reverb --sign ksk-add example.org

2. After allowing some time for propagation use the information provided by the status command to change the valid KSK within the DNSSEC interface of your domain registrar. You'll need the id, type of algo, type of hash and the digest of the active KSK.

   # dnssec-reverb status example.org
   example.org -- https://dnsviz.net/d/example.org/dnssec/
     type state  id    algo hash (expiration)        (digest)
     KSK  active 60742 13    2   set w/ registrar    53cf303e75669063c34e1f4a75bfffbbad45bd202d24f3899ccb7cf9a8b502b6
     ZSK  active 06178 13    2   2020/11/28 04:32:05
          next   43617 13    2   2020/11/28 04:32:05
   

3. After allowing some time for propagation, roll our the new KSK and remove the old one.

   dnssec-reverb ksk-roll example.org

Automated

1. Set something similar in your crontab. It will automatically add a new KSK and - assuming your email are setup correctly - send an email when you need to take action with your registrar. Optionally, you could replace the later with a script calling your registrar API to complete the rollover automagically.

0	0	1	dec		*   dessec-reverb ksk-add example.org
0	0	1	jan		*   dessec-reverb ksk-roll example.org

Rollover of the ZSK

Manual

1. Add and publish an additional and valid/signed ZSK. After this operation you will have two active ZSK.

   dnssec-reverb --sign zsk-add example.org

2. After allowing some time for the propagation you are ready to remove the old ZSK.

   dnssec-reverb -s zsk-roll example.org

3. Remove the old ZSK from reverb active records

   dnssec-reverb zsk-rmold example.org
dnssec-reverb sign example.org

Automated

Set something similar in your crontab. It will roll the ZSK at a 3 months interval by adding the new ZSK one month before publishing it and removing the old a month later.

0       6       1       jan,apr,jul,oct *   dnssec-reverb -s zsk-add example.org
0       6       1       feb,may,aug,nov *   dnssec-reverb -s zsk-roll example.org
0       6       1       mar,jun,sep,dec *   dnssec-reverb -s zsk-rmold example.org

License

Simplified BSD

Source

https://github.com/northox/dnssec-reverb

Acknowledgements

This code is heavily based on @kfujiwara work's.

Author(s)

Danny Fullerton - Mantor Organization
@kfujiwara