irl / dnssec-reverb

Automate DNSSEC key rotation - ZSK KSK (shell script)

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!

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

Installation

1. Copy dnssec-reverb into some directory.

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

2. Create a configuration file. In order of priority, the config will be searched 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/. It must specify the master zone file directory using the MASTERDIR variable.

   echo MASTERDIR="/vas/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: _SERIAL_. The file name should be equal to the zone name.

   $ grep serial example.org
   @ IN SOA ns1.example.org. dnsmaster.example.org. (
   _SERIAL_   ; 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 debug your DNSSEC chain using this tool: http://dnsviz.net/d/mantor.org/dnssec/

Configuration

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

Path:

• MASTERDIR: Master zone file directory (mandatory - no default)
• DBDIR: directory used to store state and data ($MASTERDIR/dnssec-reverb-db)
• keygen: ldns-keygen path (/usr/local/bin/ldns-keygen)
• signzone: ldns-signzone path (/usr/local/bin/ldns-signzone)
• key2ds: ldns-key2ds path (/usr/local/bin/ldns-key2ds-n)
• checkzone: nsd-checkzone path (/usr/sbin/nsd-checkzone)
• control: nsd-control path (/usr/sbin/nsd-control)
• RELOAD_COMMAND: reload command ($checkzone $ZONE $ZONE || exit 1; $control reload && $control notify)

Signatures expiration:

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

Params:

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

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 fingerprint 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

TODO

Rollover of the ZSK

Manual

1. Add next ZSK for future ZSK rollover (publish the upcomming ZSK and sign with active key)

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

2. ZSK rollover (set the published but latent ZSK created at step #3 as the active ZSK)

   dnssec-reverb -s zsk-roll example.org

3. ZSK remove old (remove the old ZSK from your records)

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

Automated

Set something similar in your crontab. This will roll the ZSK at a 4 months interval by adding the new ZSK one month ahead before publishing it and removing the old one one month later.

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