self-signed-chain (#30)

source/manual/how-tos/self-signed-chain.rst

@@ -0,0 +1,334 @@
+==================================================
+Setup Self-Signed Certificate Chains with OPNsense
+==================================================
+
+
+This how-to describes the process of creating **self-signed certificate chains**
+with the help of OPNsense which has all the tools available to do so.
+
+Chains give the possibility to verify certificates where a single one is nothing
+more than that, a single certificate.
+
+Look at the default install, one certificate is created for the webgui/dashboard. There is
+nothing wrong with that certificate if we use a real world CA, but we do not. We
+create our own chain so that one has no purpose once done.
+
+Should you even consider using **self-signed certificate chains** in this age of free available 
+certificates?
+
+   * Self-signed certificate are just as secure as real world certificates.
+   * They are trustworthy chains, you **know** all parties.
+   * Intranets are often set up with these chains.
+   * Depending on what you do with your network/servers this is a good solution.
+   * Creating your own chain will give some insight in the process.
+   * Only use them if you are sure you can. Read about the concept in common there is a lot of info on the net.
+
+What you should not do with a self-signed chain:
+
+   * Use them for a web-facing server.
+
+What you should know about self-signed certificates:
+
+   * They are **only** as trustworty as the person, company or organization signing it.
+   * Using these certificates **can** be a security risk if you are the one trusting them and not a CA.
+
+A chain will need at least a CA and certificate; an intermediate CA is not needed, but in case of a 
+compromise the CA key would be compromised too.
+
+The chain we are going to create will be made with the following ingredients:
+
+  * **CA** ``=`` certificate authority ``=`` root certificate ``-->`` signs intermediate certificates
+  * **Intermediate CA** ``=`` subordinate certificate ``=`` signed by CA  ``-->`` signs certificates
+  * **Certificate** ``=`` signed by Intermediate CA ``=`` can be used for different services
+
+.. Note::
+
+    This document uses **CN - Common Name** should be read as: **SAN - Subject Alternative Name** and 
+    will be used if present.
+
+Please backup before you proceed.
+
+
+---------------------------
+Create a Chain for OPNsense
+---------------------------
+
+
+The Authority
+-------------
+
+The first certificate to create is the **CA**. The only thing this CA
+does is sign the intermediate CA next in the line of trust.
+
+.. Note::
+
+    Self-signed root CA's anchor trust chains, they are vital and OpenSSL requires them for your chain of trust.
+
+Go to **Trust/Authorities**
+
+.. image:: images/trust.png
+
+Some entries in the form are showed here. Click on the thumbnail for a picture.
+
+When you are done save the form, the CA is now generated.
+
+====================== =================================== ========================================
+ **Descriptive name**   opnsense-ca                         *Choose a name that makes sense to you*
+ **Method**             create an internal ca               *Main purpose of CA*
+ **Common Name**        internal-ca                         *Default is fine, change to liking*
+====================== =================================== ========================================
+
+.. image:: images/CA.png
+   :scale: 15%
+
+.. Tip::
+
+    Use valid email addresses for your certificates always.
+    Bogus addresses can pose a security risk not only for certificates btw. ;-)
+
+The Intermediate
+----------------
+
+Time to create the second CA which is an **intermediate CA**. This certificate will be signed
+by the root CA we just created. In return it will sign the sever certificate for OPNsense.
+
+Go to **Trust/Authorities**
+
+Have a look at the form, create an intermediate CA and save it.
+
+====================== =================================== ========================================
+ **Descriptive name**   opnsense-ca-intermediate            *Choose a name that makes sense to you*
+ **Method**             create an intermediate ca           *Main purpose of CA*
+ **Common Name**        intermediate-ca                     *Default is fine, change to liking*
+====================== =================================== ========================================
+
+.. image:: images/CA-inter.png
+   :scale: 15%
+
+The Certificate
+---------------
+
+The thirth certificate will be a **server certificate** signed by the intermediate CA we just created.
+This will also be the last one we create for this chain.
+
+Go to **Trust/Certificates**
+
+Have a look at the next form and notice the common name, create a server certificate and save it.
+
+====================== =================================== ========================================
+ **Descriptive name**   opnsense-ca-intermediate            *Choose a name that makes sense to you*
+ **Method**             create a server certificate         *Main purpose of certificate*
+ **Common Name**        opnsense.localdomain                *This should reflect the FQDN see Tip*
+====================== =================================== ========================================
+
+.. image:: images/webgui-cert.png
+   :scale: 15%
+
+.. Tip::
+
+    When creating the server certificate make sure the **CN - common name**
+    is in fact the the **FQDN - Fully Qualified Domain Name**.
+    You can find it on **Linux/Unix** with this command ``hostname -f``
+
+Now we need to start using the chain:
+
+  * Download the intermediate CA.
+
+.. image:: images/export_CA_cert.png
+
+- * Open your browser and go to **Preferences/Certificate/Authorities**
+  * Import the downloaded CA.
+  * Go back to the dashboard & open **System/Settings/Administration**
+  * Set **SSL-Certificate** to use the new server certificate.
+
+Open your browser and open the OPNsense/webgui page. You should be presented with a certificate that is 
+verified by your intermediate CA.
+
+
+---------------------------------------
+A Chain for Your Local Nextcloud Server
+---------------------------------------
+
+
+The local chain for Nextcloud server so we can use OPNsense backup to Nextcloud.
+
+Go ahead and create a new chain **CA -- intermediate CA -- server cert.**.
+
+.. Note::
+
+    The certicate store on your OPNsense **ca-root-nss** is not aware of the CA
+    we are generating that is why we need to add this CA to the store.
+
+.. Note::
+
+    | Performing a Health audit **System/Firmware** raises an alert after adding the CA to the store:
+    | alert: **checksum mismatch for /usr/local/share/certs/ca-root-nss.crt**
+    | The sum of the file does not match the sum saved in the system after adding the CA.
+
+.. Tip::
+
+    | You can check if **ca-root-nss** has changed: 
+    | Do a health check before you add the CA.
+    | If the check was okay add the CA to the store.
+    | Create a new checksum & save it :
+    | ``cksum /usr/local/share/certs/ca-root-nss.crt > sum.txt``
+    | You can now 'always' check the sum against the result you have stored
+    | ``cksum /usr/local/share/ca-root-nss.crt | sort | diff sum.txt -``
+
+The Nextcloud Authority
+-----------------------
+
+Go to **Trust/Authorities** create a new CA for Nextcloud and save it.
+
+.. image:: images/trust.png
+
+====================== =================================== ========================================
+ **Descriptive name**   nextcloud-ca                        *Choose a name that makes sense*
+ **Method**             create a ca                         *Main purpose of CA*
+ **Common Name**        nextcloud-ca                        *Change to liking*
+====================== =================================== ========================================
+
+.. image:: images/CA-cloud.png
+   :scale: 15%
+
+OPNsense needs to be made aware of the Nextcloud chain we are creating.
+
+   * Download the **CA.crt** and upload it back to OPNsense in a secure way.
+
+.. image:: images/export_CA_cert.png
+
+-  * For this you can use ``scp`` (see) ``man scp``
+   * Install the **CA.crt** with ``cat``, you cannot just copy it to the store because it is a single file.
+
+**The following command will append it to the store**
+
+::
+
+    cat nextcloud-ca.crt >> /usr/local/share/certs/ca-root-nss.crt
+
+.. Warning::
+
+    If **ca_root_nss** is updated your certificate is removed and needs to be added overnew.
+    If you created a **sum.txt** you need to create it again, see previous Tip.
+
+.. Tip::
+
+    Remove the CA from the store? Use ``vi``, the added CA will be the
+    last one below **#End of file**
+
+The Nextcloud Intermediate CA
+-----------------------------
+
+Next in line will be the **intermediate CA** which will be signed by the root CA we did just create.
+This intermediate CA will sign the Nextcloud server certificate.
+
+Go to **Trust/Authorities** and create an intermediate CA.
+
+====================== =================================== ========================================
+ **Descriptive name**   nextcloud-intermediate-ca           *Choose a name that makes sense to you*
+ **Method**             create an intermediate ca           *Main purpose of CA*
+ **Common Name**        cloud.localdomain                   *Change to liking*
+====================== =================================== ========================================
+
+.. image:: images/CA-cloud-inter.png
+   :scale: 15%
+
+Download the intermediate CA and install it to your browser:
+
+   * Head to the webgui **Trust/Authorities** export **nextcloud-intermediate-ca.crt**
+   * Back to the browser, open **Preferences/Certificate/Authorities**
+   * Import the intermediate CA into the certificate store from your browser.
+
+The Nextcloud Server Certificate
+--------------------------------
+
+Next we create the server certificate for the Nextcloud server.
+
+Go to **Trust/Certificates** create a server certificate.
+
+====================== =================================== ========================================
+ **Descriptive name**   cloudserver-cert                    *Choose a name that makes sense to you*
+ **Method**             create a server certificate         *Main purpose of certificate*
+ **Common Name**        cloud.localdomain                   *Should reflect the FQDN*
+====================== =================================== ========================================
+
+.. image:: images/cloud-cert.png
+   :scale: 15%
+
+We need to install this certificate and key to our Nextcloud server, two ways are shown here.
+
+   * Upload the ***.p12** archive to your Nextcloud server in a safe way.
+   * Extact the archive into a single **PEM** file and create a certificate and a key.
+   * Use the following commands for a key and certificate:
+
+::
+
+   openssl pkcs12 -in nextcloud-crt.p12 -nodes -out nextcloud.key -nocerts
+   openssl pkcs12 -in nextcloud-crt.p12 -clcerts -nokeys -out nextcloud.pem
+   cp nextcloud.pem nextcloud.crt
+   
+-  * Or use the next quick and dirty method for a single key/certificate file:
+   * Upload the ***.p12**  archive to your Nextcloud server, in a safe way..
+   * Extact the archive into a single **PEM** file and create a certificate. 
+
+::
+
+    openssl pkcs12 -in nextcloud-crt.p12 -out nextcloud-crt.pem -nodes
+    cp nextcloud-crt.pem nextcloud-crt.crt
+
+-  * **/etc/ssl/localcerts** will be alright for the certificate or choose your own prefered location.
+   * If the key was extracted separatly, **/etc/ssl/private** would be a good choice.
+   * Be sure to set sane permissions on the private directory, ``700`` would do it. 
+   * You could set ``umask`` too (see) ``man umask`` - on your Linux box.
+   * Edit the webserver config to use the certificate and key or single key-cert file.
+   * Sane permissions, ``400`` read only owner is sufficent.
+
+You should now be able to backup to nextcloud and have a verified page.
+
+ - :doc:`cloud_backup`
+
+ After setting up the Nextcloud backup everything should work.
+
+Troubleshooting:
+
+| The backup to Nextcloud fails and recieve error:``verify_result 2`` in **System/LogFiles**
+| Issuer unknown because of an incomplete chain: the CA (issuer!) is missing.
+| The Nextcloud CA was not installed to OPNsense certificate store **ca-root-nss**.
+
+
+-----------------------------
+Chain for the Local Webserver
+-----------------------------
+
+
+This following **chain** we create is basically the same as the previous chain for Nextcloud server.
+
+If needed use the pictures from the Nextcloud chain.
+
+Create a chain for your server **CA - intermediate CA - server cert.**
+
+Once done go through the following points:
+
+   * Download the server.p12 archive.
+   * Upload it to the server and extract the archive.
+   * Store the certificate and key respectively in **/etc/ssl/localcerts** and **/etc/ssl/private**
+   * Use the following commands for that:
+
+::
+
+   openssl pkcs12 -in server.p12 -nodes -out server.key -nocerts
+   openssl pkcs12 -in server.p12 -clcerts -nokeys -out server.pem
+   cp server.pem server.crt
+
+Or if you want to use a single file:
+
+::
+
+    openssl pkcs12 -in some-server-crt.p12 -out some-server-crt.pem -nodes
+    cp some-server-crt.pem some-server-crt.crt
+
+-  * Some sane permissions on them.
+   * Set the server to use the installed certificate.
+   * Download the intermediate CA.
+   * Install it in your browser.
+   * Head to the webservers page and be presented with a verified certificate.