Evaggelos Balaskas - System Engineer

ACME v2 and Wildcard Certificate Support is Live

We have some good news, letsencrypt support wildcard certificates! For more details click here.

The key phrase on the post is this:

Certbot has ACME v2 support since Version 0.22.0.

unfortunately -at this momment- using certbot on a centos6 is not so trivial, so here is an alternative approach using:

• acme.sh
• PowerDNS

acme.sh

acme.sh is a pure Unix shell script implementing ACME client protocol.

# curl -LO https://github.com/Neilpang/acme.sh/archive/2.7.7.tar.gz
# tar xf 2.7.7.tar.gz

# cd acme.sh-2.7.7/

[acme.sh-2.7.7]# ./acme.sh --version
https://github.com/Neilpang/acme.sh
v2.7.7

PowerDNS

I have my own Authoritative Na,e Server based on powerdns software.

PowerDNS has an API for direct control, also a built-in web server for statistics.

To enable these features make the appropriate changes to pdns.conf

api=yes
api-key=0123456789ABCDEF
webserver-port=8081

and restart your pdns service.

To read more about these capabilities, click here: Built-in Webserver and HTTP API

testing the API:

# curl -s -H 'X-API-Key: 0123456789ABCDEF' http://127.0.0.1:8081/api/v1/servers/localhost | jq .

{
  "zones_url": "/api/v1/servers/localhost/zones{/zone}",
  "version": "4.1.1",
  "url": "/api/v1/servers/localhost",
  "type": "Server",
  "id": "localhost",
  "daemon_type": "authoritative",
  "config_url": "/api/v1/servers/localhost/config{/config_setting}"
}

Enviroment

export PDNS_Url="http://127.0.0.1:8081"
export PDNS_ServerId="localhost"
export PDNS_Token="0123456789ABCDEF"
export PDNS_Ttl=60

Prepare Destination

I want to save the certificates under /etc/letsencrypt directory.
By default, acme.sh will save certificate files under /root/.acme.sh/balaskas.gr/ path.

I use selinux and I want to save them under /etc and on similar directory as before, so:

# mkdir -pv /etc/letsencrypt/acme.sh/balaskas.gr/

Create WildCard Certificate

Run:

# ./acme.sh
  --issue
  --dns dns_pdns
  --dnssleep 30
  -f
  -d balaskas.gr
  -d *.balaskas.gr
  --cert-file /etc/letsencrypt/acme.sh/balaskas.gr/cert.pem
  --key-file  /etc/letsencrypt/acme.sh/balaskas.gr/privkey.pem
  --ca-file   /etc/letsencrypt/acme.sh/balaskas.gr/ca.pem
  --fullchain-file /etc/letsencrypt/acme.sh/balaskas.gr/fullchain.pem

HSTS

Using HTTP Strict Transport Security means that the browsers probably already know that you are using a single certificate for your domains. So, you need to add every domain in your wildcard certificate.

Web Server

Change your VirtualHost

from something like this:

SSLCertificateFile /etc/letsencrypt/live/balaskas.gr/cert.pem
SSLCertificateKeyFile /etc/letsencrypt/live/balaskas.gr/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateChainFile /etc/letsencrypt/live/balaskas.gr/chain.pem

to something like this:

SSLCertificateFile    /etc/letsencrypt/acme.sh/balaskas.gr/cert.pem
SSLCertificateKeyFile /etc/letsencrypt/acme.sh/balaskas.gr/privkey.pem
Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateChainFile /etc/letsencrypt/acme.sh/balaskas.gr/fullchain.pem

and restart your web server.

Browser

Quallys

Qualys SSL Server Test)

Validation

X509v3 Subject Alternative Name

# openssl x509 -text -in /etc/letsencrypt/acme.sh/balaskas.gr/cert.pem | egrep balaskas

        Subject: CN=balaskas.gr
                DNS:*.balaskas.gr, DNS:balaskas.gr