I use an Apache2 as proxy for several backend-server. The proxy holds the Let´s-Encrypt-SSL-Certificates for all servers, http-traffic is redirected to https and then proxyed to the http-backend-servers.

Everything is running smoothly, but:

One of the backend-servers hold a Moodle-Installation. Every link points to the http-url, so browsers say, there is insecure content...

How can I manipulate the page-content, that is delivered from the backend via the proxy to the client? I will have to replace every link "http://my.doimain.com/" with "https://my.domain.com/" within the delivered pages...

The traffic between proxy and backend-serer is http, not https. As theses servers have no internet-access they cannot update certificates issued by let´s encrypt...

Thanks in advance wepp


Two possible approaches:

  • Install certificates on the back-end servers so they can support https and then reconfigure the web application to run on the HTTPS back-end so that it will generate https links when referencing to itself.
    You don't need a valid certificate and can make do with a self-signed certificate on the back-end server(s) because by default mod_proxy_http does not check the certificate (see SSLProxyVerify)

  • You can rewrite the HTML pages your web application generates and rewrite any occurrence of http://www.example.com with mod_proxy_html and the ProxyHTMLURLMap Directive. A basic example would be:

    ProxyHTMLURLMap http://internal2.example.com https://www.example.com

Thanks HBruijn, you pointed me to the right direction.

Here is everything you need for getting this to work...
Within your VirtualHost-File add after the SSL-settings:

<VirtualHost *:443>
ProxyPass / http://backend-server/
ProxyPreserveHost On

SetOutputFilter INFLATE;proxy-html;DEFLATE
ProxyHTMLExtended Off
ProxyHTMLInterp On
ProxyHTMLDoctype XHTML Legacy
ProxyPassReverse / http://backend-server/

ProxyHTMLURLMap http://external.server.address https://external.server.address


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