Some notes on the configuration of my setup
All services accessible from the internet run in jails (all jails reside in /usr/jails by default on FreeBSD)
I use LibreSSL (LibreSSL port)
I use The Z Shell (zsh port)
Things that don't need to run as root will be running as an unprivileged user. I will use the user _letsencrypt with group _letsencrypt as the unprivileged user that will perform the certificate renewal process. Deployment of the keys and certificates will have to be executed with a privileged user, this guide uses root.
Install Letsencrypt.sh
The port is available in the ports tree. Install it using the official pkg repository using
pkg install letsencrypt.sh
or alternatively (e.g. when you want to use ZSH) build your own using Poudriere or any of the other building-from-source options and install it. The port works with either zsh or bash.
This will install the actual script into /usr/local/bin. Configuration will land in /usr/local/etc/letsencrypt.sh as will the keys, certificates and certificate-chains. You should want to check that the configuration directory is not world-writable.
Prepare user & directories
To make life easier all of the challenges (LetsEncrypt as well as keybase etc) will be hosted in a shared dir /usr/local/www/.well-known on the jail running my Apache server. The LetsEncrypt bits will land in /usr/local/etc/letsencrypt.sh on the host system. There's no requirement to run the interaction with the LetsEncrypt servers as root, so these will run as a non-privileged user. This unprivileged user will have to write to the acme-challenge and the directory that will contain the keys and certificates.
pw groupadd -n _letsencrypt -g 443
pw useradd -n _letsencrypt -u 443 -g 443 -d /usr/local/etc/letsencrypt.sh -w no -s /nonexistent
chown root:_letsencrypt /usr/local/etc/letsencrypt.sh
chmod 770 /usr/local/etc/letsencrypt.sh
mkdir -p -m 775 /usr/jails/http/usr/local/www/.well-known/acme-challenge
chgrp _letsencrypt /usr/jails/http/usr/local/www/.well-known/acme-challenge
Adapt the .well-known/acme-challenge directory to your situation.
Modify Apache configuration
The acme validation will GET a uniquely named file from http://<example.org>/.well-known/acme-challenge/
Access to the .well-known directory is granted in my main Apache config file /usr/local/etc/apache24/httpd.conf
<Directory "/usr/local/www/.well-known/">
Options None
AllowOverride None
Require all granted
Header add Content-Type text/plain
</Directory>
The Content-Type header was in my configs somewhere, shouldn't hurt.
If you want to only share the ACME challenges you can suffix .well-known/ with acme-challenge/
Now every (non-ssl) Virtual Host that I have gets a on-line addition
Alias /.well-known/ /usr/local/www/.well-known/
You need to make sure that all (sub-)domains that you want to sign have access to this directory!
That includes rewrites etc.
The acme validation is done only using plain http and will not honour redirects etc.
Letsencrypt configuration
Domains to sign
The script requires a list of domain names you want to have a SAN cert for in the following format:
example.com www.example.com example.net www.example.net wiki.example.net
Domains and sub-domains that are listed on the same line will result in SAN-certificates (Subject-Alternative-Name).
Store this as /usr/local/etc/letsencrypt.sh/domains.txt
The default configuration file requires some changes, these are stored in /usr/local/etc/letsencrypt.sh/config.sh
BASEDIR="/usr/local/etc/letsencrypt.sh"
WELLKNOWN="/usr/jails/http/usr/local/www/.well-known/acme-challenge"
alias openssl='/usr/local/bin/openssl'
To make use of LibreSSL (or OpenSSL from ports) you must add the alias openssl to the config script.
Configure periodic job
The security/letsencrypt.sh port includes a periodic job that makes automation very simple. To automatically renew certificates, add the following to your /etc/periodic.conf
weekly_letsencrypt_enable="YES"
weekly_letsencrypt_user="_letsencrypt"
weekly_letsencrypt_deployscript="/usr/local/etc/letsencrypt.sh/deploy.sh"
First run
You will probably want to run LetsEncrypt manually the first time
cd /usr/local/etc/letsencrypt.sh
su -m _letsencrypt -c 'zsh /usr/local/bin/letsencrypt.sh --cron'
(Replace zsh with bash if that's the shell you have installed)
You will end up with a sub-directory certs that contains your domains as directories with the Subject-Alternative-Names certs and the corresponding private keys. The symbolic links are useful for deployment.
example.com/ cert-1453573903.csr cert-1453573903.pem cert.csr -> cert-1453573903.csr cert.pem -> cert-1453573903.pem chain-1453573903.pem chain.pem -> chain-1453573903.pem fullchain-1453573903.pem fullchain.pem -> fullchain-1453573903.pem privkey-1453573903.pem privkey.pem -> privkey-1453573903.pem example.net/ cert-1453576309.csr cert-1453576309.pem cert.csr -> cert-1453576309.csr cert.pem -> cert-1453576309.pem chain-1453576309.pem chain.pem -> chain-1453576309.pem fullchain-1453576309.pem fullchain.pem -> fullchain-1453576309.pem privkey-1453576309.pem privkey.pem -> privkey-1453576309.pem
Deploy new certs
We've run the certificate request process as a restricted user but you'll need to run the deploy script as root.
Here you'll probably need to get creative with scripting. In the host environment, your now have
/usr/local/etc/letsencrypt.sh/certs/example.net/privkey.pem
/usr/local/etc/letsencrypt.sh/certs/example.net/fullchain.pem
NB: These are symlinks!!!
Example (jailed) applications
Your Apache server may (should?) run in the http jail and you've setup an Apache Virtual Host with
SSLCertificateFile /etc/ssl/certs/example.net.pem
SSLCertificateKeyFile /etc/ssl/priv/example.net.pem
and your OpenSMTPd mailserver for example.net in the mail jail
pki example.net certificate "/etc/ssl/certs/example.net.pem" pki example.net key "/etc/ssl/priv/example.net.pem" listen on $lan_addr port 587 tls-require \ pki example.net hostname example.net auth
Seen from the host environment your certificates actually need to end up in
/usr/jails/```http```/etc/ssl /usr/jails/```mail```/etc/ssl
Example deployment script
You could use the following script to deploy new certs
#!/bin/sh
domain="example.net"
letsencryptdir="/usr/local/etc/letsencrypt.sh"
targets="mail http"
for jail in ${targets}; do
targetdir="/usr/jails/${jail}/etc/ssl"
# Check if the certificate has changed
[ -z "`diff -rq ${letsencryptdir}/certs/${domain}/fullchain.pem ${targetdir}/certs/${domain}.pem`" ] && continue
cp -L "${letsencryptdir}/certs/${domain}/privkey.pem" "${targetdir}/priv/${domain}.pem"
cp -L "${letsencryptdir}/certs/${domain}/fullchain.pem" "${targetdir}/certs/${domain}.pem"
chmod 400 "${targetdir}/priv/${domain}.pem"
chmod 644 "${targetdir}/certs/${domain}.pem"
# Restart/-load relevant services
[ "${jail}" = "http" ] && jexec ${jail} service apache24 restart
[ "${jail}" = "mail" ] && jexec ${jail} service smtpd restart
done
# Clean up old keys and certs
/usr/local/bin/letsencrypt.sh --cleanup
Store this as /usr/local/etc/letsencrypt.sh/deploy.sh and make sure the execute bit is set.
NB: Some applications want a private key, certificate and separate chain instead. If this is the case you'll need to copy cert.pem and chain.pem to the appropriate location in stead.