Debian Buster Zammad
Configurar Elastic Search
<code bash>
apt install apt-transport-https sudo wget
echo "deb https://artifacts.elastic.co/packages/7.x/apt stable main" | tee -a /etc/apt/sources.list.d/elastic-7.x.list
wget -qO - https://artifacts.elastic.co/GPG-KEY-elasticsearch | apt-key add -
apt update
apt install elasticsearch
/usr/share/elasticsearch/bin/elasticsearch-plugin install ingest-attachment

systemctl start elasticsearch
systemctl enable elasticsearch

cat /etc/elasticsearch/elasticsearch.yml
</code>

Install Zammad
<code bash>
apt install wget apt-transport-https gnupg
wget -qO- https://dl.packager.io/srv/zammad/zammad/key | apt-key add -
wget -O /etc/apt/sources.list.d/zammad.list \
https://dl.packager.io/srv/zammad/zammad/stable/installer/debian/10.repo
apt update
apt install zammad

# Zammad service to start all services at once
systemctl (status|start|stop|restart) zammad

# Zammads internal railsserver
systemctl (status|start|stop|restart) zammad-web

# Zammads scheduler - relevant for all delayed- and background jobs
systemctl (status|start|stop|restart) zammad-worker

# Zammads websocket server for session related information
systemctl (status|start|stop|restart) zammad-websocket


# Set the Elasticsearch server address
zammad run rails r "Setting.set('es_url', 'http://localhost:9200')"

# Build the search index
zammad run rake searchindex:rebuild


</code>
Configurar servidor web
<code bash>
apt install certbot python3-certbot-nginx  python-certbot-nginx

</code>

Configurar Nginx

<code bash>
cp /opt/zammad/contrib/nginx/zammad_ssl.conf /etc/nginx/sites-enabled/zammad.conf
</code>
Cambiar en el archivo la linea 

''    proxy_set_header X-Forwarded-User "";''

Por

''   proxy_set_header X-Forwarded-Proto https;''

y reiniciar el servidor web.
====== Referencias ======
  * https://docs.zammad.org/en/latest/install/package.html
  * https://docs.zammad.org/en/latest/install/elasticsearch.html
  * https://community.zammad.org/t/fresh-install-3-2-x-csrf-token-verification-failed/3080/18
  * https://community.zammad.org/t/how-to-reset-admin-password-from-ruby-cli/82