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300 lines
12 KiB
ReStructuredText
==================================================
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Setup Self-Signed Certificate Chains with OPNsense
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==================================================
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This how-to describes the process of creating **self-signed certificate chains**
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with the help of OPNsense which has all the tools available to do so.
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Chains give the possibility to verify certificates where a single one is nothing
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more than that, a single certificate.
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Look at the default install, one certificate is created for the webgui/dashboard. There is
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nothing wrong with that certificate if we use a real world CA, but we do not. We
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create our own chain so that one has no purpose once done.
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Should you even consider using **self-signed certificate chains** in this age of free available
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certificates?
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* Self-signed certificate are just as secure as real world certificates.
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* They are trustworthy chains, you **know** all parties.
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* Intranets are often set up with these chains.
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* Depending on what you do with your network/servers this is a good solution.
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* Creating your own chain will give some insight in the process.
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* Only use them if you are sure you can. Read about the concept in common there is a lot of info on the net.
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* They are required for intercepted connections (see proxy chapter)
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What you should not do with a self-signed chain:
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* Use them for a web-facing server.
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* Intercept encrypted traffic on a public wireless network (for example if you provide access in a hotel)
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What you should know about self-signed certificates:
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* They are **only** as trustworty as the person, company or organization signing it, this is also true for trusted certificates.
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A chain will need at least a CA and certificate; an intermediate CA is not needed, but in case of a
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compromise the CA key would be compromised too.
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The CA private key should be stored offline on an USB stick/HD and put in a safe, not reachable by malicious software or criminals/burglers.
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The intermediate CA, which is intended for a shorter lifetime can be kept on the firewall host.
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The chain we are going to create will be made with the following ingredients:
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* **CA** ``=`` certificate authority ``=`` root certificate ``-->`` signs intermediate certificates
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* **Intermediate CA** ``=`` subordinate certificate ``=`` signed by CA ``-->`` signs certificates
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* **Certificate** ``=`` signed by Intermediate CA ``=`` can be used for different services
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Please backup before you proceed.
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---------------------------
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Create a Chain for OPNsense
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---------------------------
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The Authority
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-------------
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The first certificate to create is the **CA**. The only thing this CA
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does is sign the intermediate CA next in the line of trust.
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.. Note::
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Self-signed root CA's anchor trust chains, they are vital and OpenSSL requires them for your chain of trust.
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Go to **Trust/Authorities**
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.. image:: images/trust.png
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Some entries in the form are showed here. Click on the thumbnail for a picture.
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When you are done save the form, the CA is now generated.
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====================== =================================== ========================================
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**Descriptive name** opnsense-ca *Choose a name that makes sense to you*
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**Method** create an internal ca *Main purpose of CA*
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**Common Name** internal-ca *Default is fine, change to liking*
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**Lifetime(days)** 3650 *Longer is also no problem for CA*
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====================== =================================== ========================================
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.. image:: images/CA.png
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:width: 100%
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.. Tip::
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Always use valid email addresses for your certificates.
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Bogus addresses can pose a security risk - and not only for certificates.
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F.I.: If one should use user@example.com and someone claims example.com mail will be send there!
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The Intermediate
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----------------
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Time to create the second CA, which is an **intermediate CA**. This certificate will be signed
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by the root CA we just created. In return it will sign the sever certificate for OPNsense.
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Go to **Trust/Authorities**
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Have a look at the form, create an intermediate CA and save it.
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====================== =================================== ========================================
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**Descriptive name** opnsense-ca-intermediate *Choose a name that makes sense to you*
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**Method** create an intermediate ca *Main purpose of CA*
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**Common Name** intermediate-ca *Default is fine, change to liking*
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====================== =================================== ========================================
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.. image:: images/CA-inter.png
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:width: 100%
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The Certificate
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---------------
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The third certificate will be a **server certificate** signed by the intermediate CA we just created.
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This will also be the last one we create for this chain.
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Go to **Trust/Certificates**
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Have a look at the next form and notice the common name, create a server certificate and save it.
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====================== =================================== ========================================
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**Descriptive name** opnsense-ca-intermediate *Choose a name that makes sense to you*
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**Method** create a server certificate *Main purpose of certificate*
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**SAN** opnsense.localdomain *This should reflect the FQDN see Tip*
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====================== =================================== ========================================
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.. image:: images/webgui-cert.png
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:width: 100%
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.. Tip::
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When creating the server certificate make sure the **SAN - Subject Alternative Name**
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is in fact the the **FQDN - Fully Qualified Domain Name**.
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You can find it on **Linux/Unix** with this command ``hostname -f``
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Now we need to start using the chain:
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* Download the intermediate CA.
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.. image:: images/export_CA_cert.png
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- * Open your browser and go to **Preferences/Certificate/Authorities**
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* Import the downloaded CA.
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* Go back to the dashboard & open **System/Settings/Administration**
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* Set **SSL-Certificate** to use the new server certificate.
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Open your browser and open the OPNsense/webgui page. You should be presented with a certificate that is
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verified by your intermediate CA.
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---------------------------------------
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A Chain for Your Local Nextcloud Server
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---------------------------------------
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The local chain for Nextcloud server so we can use OPNsense backup to Nextcloud.
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Go ahead and create a new chain **CA -- intermediate CA -- server cert.**.
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The Nextcloud Authority
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-----------------------
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Go to **Trust/Authorities** create a new CA for Nextcloud and save it.
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.. image:: images/trust.png
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====================== =================================== ========================================
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**Descriptive name** nextcloud-ca *Choose a name that makes sense*
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**Method** create a ca *Main purpose of CA*
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**Common Name** nextcloud-ca *Change to liking*
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**Lifetime(days)** 3650 *Longer is also no problem for CA*
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====================== =================================== ========================================
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.. image:: images/CA-cloud.png
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:width: 100%
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The Nextcloud Intermediate CA
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-----------------------------
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Next in line will be the **intermediate CA** which will be signed by the root CA we did just create.
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This intermediate CA will sign the Nextcloud server certificate.
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Go to **Trust/Authorities** and create an intermediate CA.
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====================== =================================== ========================================
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**Descriptive name** nextcloud-intermediate-ca *Choose a name that makes sense to you*
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**Method** create an intermediate ca *Main purpose of CA*
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**Common Name** cloud.localdomain *Change to liking*
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====================== =================================== ========================================
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.. image:: images/CA-cloud-inter.png
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:width: 100%
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Download the intermediate CA and install it to your browser:
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* Head to the webgui **Trust/Authorities** export **nextcloud-intermediate-ca.crt**
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* Back to the browser, open **Preferences/Certificate/Authorities**
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* Import the intermediate CA into the certificate store from your browser.
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The Nextcloud Server Certificate
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--------------------------------
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Next we create the server certificate for the Nextcloud server.
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Go to **Trust/Certificates** create a server certificate.
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====================== =================================== ========================================
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**Descriptive name** cloudserver-cert *Choose a name that makes sense to you*
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**Method** create a server certificate *Main purpose of certificate*
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**SAN** cloud.localdomain *Should reflect the FQDN*
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====================== =================================== ========================================
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.. image:: images/cloud-cert.png
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:width: 100%
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We need to install this certificate and key to our Nextcloud server, two ways are shown here.
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* Upload the ***.p12** archive to your Nextcloud server in a safe way.
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* Extact the archive into a single **PEM** file and create a certificate and a key.
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* Use the following commands for a key and certificate:
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::
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openssl pkcs12 -in nextcloud-crt.p12 -nodes -out nextcloud.key -nocerts
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openssl pkcs12 -in nextcloud-crt.p12 -clcerts -nokeys -out nextcloud.pem
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cp nextcloud.pem nextcloud.crt
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- * Or download the key and certificate separately from OPNsense.
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* If SSH is used '-i private-key' is not needed.
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::
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scp -i ~/id_ed25519 /path/to/private/nextcloud.key /etc/ssl/keys/nextcloud.key
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scp -i ~/id_ed25519 /path/to/nextcloud.pem /etc/ssl/localcerts/nextcloud.pem
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- * Or use the next quick and dirty method for a single key/certificate file:
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* Upload the ***.p12** archive to your Nextcloud server, in a safe way..
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* Extact the archive into a single **PEM** file and create a certificate.
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::
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openssl pkcs12 -in nextcloud-crt.p12 -out nextcloud-crt.pem -nodes
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cp nextcloud-crt.pem nextcloud-crt.crt
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- * **/etc/ssl/localcerts** will be alright for the certificate or choose your own prefered location.
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* If the key was extracted separatly, **/etc/ssl/private** would be a good choice.
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* Be sure to set sane permissions on the private directory, ``755`` would do it.
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* You could set ``umask`` too (see) ``man umask`` - on your Linux box.
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* Edit the webserver config to use the certificate and key or single key-cert file.
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* Sane permissions, ``400`` read only owner is sufficent.
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You should now be able to backup to Nextcloud and have a verified page.
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- :doc:`cloud_backup`
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After setting up the Nextcloud backup everything should work.
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-----------------------------
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Chain for the Local Webserver
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-----------------------------
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This following **chain** we create is basically the same as the previous chain for Nextcloud server.
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If needed use the pictures from the Nextcloud chain.
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Create a chain for your server **CA - intermediate CA - server cert.**
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Once done go through the following points:
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* Download the server.p12 archive.
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* Upload it to the server and extract the archive.
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* Store the certificate and key respectively in **/etc/ssl/localcerts** and **/etc/ssl/private**
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* Use the following commands for that:
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::
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openssl pkcs12 -in server.p12 -nodes -out server.key -nocerts
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openssl pkcs12 -in server.p12 -clcerts -nokeys -out server.pem
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cp server.pem server.crt
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- * Or download the key and certificate separately from OPNsense.
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* If SSH is used '-i private-key' is not needed.
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::
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scp -i ~/id_ed25519 /path/to/private/server.key /etc/ssl/keys/server.key
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scp -i ~/id_ed25519 /path/to/server.pem /etc/ssl/localcerts/server.pem
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- * Or if you want to use a single file:
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::
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openssl pkcs12 -in some-server-crt.p12 -out some-server-crt.pem -nodes
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cp some-server-crt.pem some-server-crt.crt
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- * Some sane permissions on them.
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* Set the server to use the installed certificate.
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* Download the intermediate CA.
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* Install it in your browser.
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* Head to the webservers page and be presented with a verified certificate.
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