You can use Letsencrypt certificates for the Ispconfig admin console too.
In order to achieve this, you can use the following commands:
### as super user of course
DOMAIN="www.mydomain.com"
letsencrypt auth --text --agree-tos --authenticator webroot --server https://acme-v01.api.letsencrypt.org/directory --rsa-key-size 4096 --email postmaster@${DOMAIN} --domains ${DOMAIN} --webroot-path /usr/local/ispconfig/interface/acme
dt=`date '+%Y%m%d%H%M%S'`
cd /usr/local/ispconfig/interface/ssl/
for ext in csr key.secure key crt
do
if [ -f ispserver.$ext ]
then
mv ispserver.$ext ispserver.$ext.old.$dt
fi
done
ln -s /etc/letsencrypt/live/${DOMAIN}/privkey.pem ispserver.key
ln -s /etc/letsencrypt/live/${DOMAIN}/fullchain.pem ispserver.crt
service apache2 restart
