* CM_certmatch defines the domains that are allowed to use DNS auth.<br>to allow all: `export CM_certmatch="."`<br>To allow a specific subdomain: `export CM_certmatch="\.org\.example\.com"`
* CM_challenge_alias is the domain you can manage via DNS api. <br>All hosts of this domain will be issued by a TXT record.<br>External domains need a CNAME. See <https://github.com/acmesh-official/acme.sh/wiki/DNS-alias-mode>
#### Mehtod: Http - using webroot
If you have a http website of a domain you can authorize with a written challenge file. The file will be written below webroot.
The SSL provider will make an http request `http://www.example.com/.well-known/acme-challenge/<generated-challenge-file>`
The parameter --webroot is used to define the webroot of the existing web (without /.well-known/acme-challenge).
You can use an alias to place the generated challenge file outside webroot.
The SSL provider will make an http request `http://www.example.com/.well-known/acme-challenge/<generated-challenge-file>` - this url must fit here too.
(1) Create a .well-known directory
Remark: this path is hardcoded :-/
The directory is ../alias-dir/ - one directory outside the cm.sh.
If your installation is in `/opt/letsencrypt/iml-certman/` then you need to create this directory: `/opt/letsencrypt/alias-dir/.well-known`
(2) In Webserver enable mod_alias
eg. on Debian /etc/apache2/mods-enabled/alias.load