first pass

content/posts/create-your-own-ca-cert.md

@@ -4,38 +4,43 @@ description: ""
 date: "2023-01-27"
 tags:
 - SSL
-draft: true
+draft: false
 ---
 
+Even though there are plenty of free SSL certificate options, you may need to manage your own SSL certs for various reasons.
+
+Below is how to create a CA certificate and issue certs signed with it, as well as some validation steps to make sure you did everything right.
+
+All examples here use the [openssl](https://www.openssl.org/docs/man1.1.1/man1/) cli tool.
+
 
 ## Creating the Certificate Authority's Certificate and Keys
 
 1.  Generate a private key for the CA:
-```
+```sh
 $ openssl genrsa 4096 > ca-key.pem
 ```
 
 2.  Generate the X509 certificate for the CA:
-```
+```sh
     $ openssl req -new -x509 -nodes -days 3650 -sha256 \
-	   -subj "/C=US/ST=CO/O=Automox, Inc./OU=Engineering/CN=ca.example.internal" \
+	   -subj "/C=US/ST=CO/O=My Org, Inc./OU=Engineering/CN=ca.example.internal" \
        -key ca-key.pem \
        -out ca-cert.pem
-
 ```
 
 ## Creating the Server's Certificate and Keys
 
 1.  Generate the private key and certificate request:
-```
-$ openssl req -newkey rsa:4096 -nodes -days 3650 -sha256 \
-	-subj "/CN=mydomain.com" \ # exclude this and you will get interactive prompts
+```sh
+$ openssl req -newkey rsa:4096 -nodes -days 3650 -sha256 \ # -newkey if you need a new private key
+	-subj "/CN=mysite.example.internal" \ # exclude this and you will get interactive prompts
 	-keyout server-key.pem \
 	-out server-req.pem
 
 # if you already have a private key
 $ openssl req -new -nodes -days 3650 -sha256 \
-	-subj "/CN=mydomain.com" \
+	-subj "/CN=mysite.example.internal" \
 	-key server-key.pem \
 	-out server-req.pem
 
@@ -43,18 +48,20 @@ $ openssl req -new -nodes -days 3650 -sha256 \
 $ openssl req -new -nodes -days 3650 -sha256 \
 	-subj "/CN=mydomain.com" \
 	-reqexts SAN \
-	-config <(cat /etc/ssl/openssl.cnf <(printf "\n[SAN]\nsubjectAltName=DNS:mydomain.com,DNS:www.mydomain.com")) \ # to add SANs
+	-config <(cat /etc/ssl/openssl.cnf <(printf "\n[SAN]\nsubjectAltName=DNS:test.example.internal,DNS:www.example.internal")) \ # to add SANs
 	-key server-key.pem \
 	-out server-req.pem
 ```
 
 
 2.  Generate the X509 certificate for the server:
-> `-days` expiration can be no longer than 398 days (13 months) (thanks Apple)
-> https://support.apple.com/en-us/HT211025
+
+> `-days` expiration can be no longer than 398 days (13 months) (thanks [Apple](https://support.apple.com/en-us/HT211025))
 > https://www.globalsign.com/en/blog/maximum-ssltls-certificate-validity-now-one-year
-> `-set_serial` must be a positive integer and unique to each cert signed by the CA. `date +%s` prints the current number of seconds since the Epoch (00:00:00 UTC, January 1, 1970). See [RFC 5280](https://datatracker.ietf.org/doc/html/rfc5280#section-4.1.2.2 "https://datatracker.ietf.org/doc/html/rfc5280#section-4.1.2.2") for details
-```
+> `-set_serial` is like an ID number for each cert. It must be a positive integer and unique to each cert signed by the CA.
+> `date +%s` prints the current number of seconds since the Epoch (00:00:00 UTC, January 1, 1970). See [RFC 5280](https://datatracker.ietf.org/doc/html/rfc5280#section-4.1.2.2 "https://datatracker.ietf.org/doc/html/rfc5280#section-4.1.2.2") for details
+
+```sh
 $ openssl x509 -req -days 398 -set_serial $(date +%s) -sha256 \
    -in server-req.pem \
    -out server-cert.pem \
@@ -74,14 +81,14 @@ $ openssl x509 -req -days 398 -set_serial $(date +%s) -sha256 \
 
 1.  Verify the server certificate:
 
-```
+```sh
     $ openssl verify -CAfile ca-cert.pem \
        ca-cert.pem \
        server-cert.pem
 ```
-2.  Verify the client certificate:
 
-```
+2.  Verify the client certificate:
+```sh
     $ openssl verify -CAfile ca-cert.pem \
        ca-cert.pem \
        client-cert.pem
@@ -89,6 +96,6 @@ $ openssl x509 -req -days 398 -set_serial $(date +%s) -sha256 \
 
 ## Verify the certificate's content
 
-```
+```sh
 openssl x509 -in mydomain.com.crt -text -noout
 ```