There are multiple modes to the letscrypt client. The [webroot mode](<a href="https:&#x2F;&#x2F;github.com&#x2F;letsencrypt&#x2F;letsencrypt&#x2F;issues&#x2F;1370" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;letsencrypt&#x2F;letsencrypt&#x2F;issues&#x2F;1370</a>) allows you to use an existing web server.