README: add Root CA certificate DST Root CA X3

This is used by Let's Encrypt to cross-sign.

README.md

@@ -52,22 +52,30 @@ files to your MikroTik device.
 Then we import the certificates.
 
     [admin@MikroTik] > / certificate import file-name=letsencrypt.pem passphrase=""
-         certificates-imported: 2
+         certificates-imported: 3
          private-keys-imported: 0
                 files-imported: 1
            decryption-failures: 0
       keys-with-no-certificate: 0
 
 For basic verification we rename the certifiactes and print their count. Make
-sure the certificate count is **two**.
+sure the certificate count is **three**.
 
     [admin@MikroTik] > / certificate set name="ISRG-Root-X1" [ find where fingerprint="96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6" ]
     [admin@MikroTik] > / certificate set name="Let-s-Encrypt-Authority-X3" [ find where fingerprint="731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568" ]
-    [admin@MikroTik] > / certificate print count-only where fingerprint="96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6" or fingerprint="731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568"
+    [admin@MikroTik] > / certificate set name="DST-Root-CA-X3" [ find where fingerprint="0687260331a72403d909f105e69bcf0d32e1bd2493ffc6d9206d11bcd6770739" ]
-    2
+    [admin@MikroTik] > / certificate print count-only where fingerprint="96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6" or fingerprint="731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568" or fingerprint="0687260331a72403d909f105e69bcf0d32e1bd2493ffc6d9206d11bcd6770739"
+    3
 
 Always make sure there are no certificates installed you do not know or want!
 
+Actually we do not require the certificate named `DST Root CA X3`, but as it
+is used by `Let's Encrypt` to cross-sign we install it anyway - this makes
+sure things do not go wrong if the intermediate certificate is replaced.
+The IdenTrust certificate *should* be available from their
+[download page](https://www.identrust.com/support/downloads). The site is
+crap and a good example how to *not* do it.
+
 Now let's download the main scripts and add them in configuration on the fly.
 
     [admin@MikroTik] > :foreach script in={ "global-config"; "global-functions"; "script-updates" } do={ / system script add name=$script source=([ / tool fetch check-certificate=yes-without-crl ("https://git.eworm.de/cgit.cgi/routeros-scripts/plain/" . $script) output=user as-value]->"data"); }

certs/731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568.pem

@@ -61,3 +61,23 @@ ayLThlHLN81gSkJjVrPI0Y8xCVPB4twb1PFUd2fPM3sA1tJ83sZ5v8vgFv2yofKR
 PB0t6JzUA81mSqM3kxl5e+IZwhYAyO0OTg3/fs8HqGTNKd9BqoUwSRBzp06JMg5b
 rUCGwbCUDI0mxadJ3Bz4WxR6fyNpBK2yAinWEsikxqEt
 -----END CERTIFICATE-----
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----

initial-commands

@@ -8,7 +8,8 @@
   / certificate import file-name=letsencrypt.pem passphrase="";
   / certificate set name="ISRG-Root-X1" [ find where fingerprint="96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6" ];
   / certificate set name="Let-s-Encrypt-Authority-X3" [ find where fingerprint="731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568" ];
-  :if ([ / certificate print count-only where fingerprint="96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6" or fingerprint="731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568" ] != 2) do={
+  / certificate set name="DST-Root-CA-X3" [ find where fingerprint="0687260331a72403d909f105e69bcf0d32e1bd2493ffc6d9206d11bcd6770739" ];
+  :if ([ / certificate print count-only where fingerprint="96bcec06264976f37460779acf28c5a7cfe8a3c0aae11a8ffcee05c0bddf08c6" or fingerprint="731d3d9cfaa061487a1d71445a42f67df0afca2a6c2d2f98ff7b3ce112b1f568" or fingerprint="0687260331a72403d909f105e69bcf0d32e1bd2493ffc6d9206d11bcd6770739" ] != 3) do={
     :error "Anything is wrong with your certificates!";
   }
   :foreach script in={ "global-config"; "global-functions"; "script-updates" } do={