.NET 8 | Kestrel: ERR_CERT_COMMON_NAME_INVALID When generating self-signed ssl certificate for my local IP

Question

I'm trying to generate a self-signed SSL certificate from this .cnf file:

[req]
default_bits  = 2048
distinguished_name = req_distinguished_name
req_extensions = req_ext
x509_extensions = v3_req
prompt = no

[req_distinguished_name]
countryName = BR
stateOrProvinceName = SC
localityName = PB
organizationName = MyCompany
CN = 20.14.3.12 // My Local IPv4

[req_ext]
subjectAltName = @alt_names

[v3_req]
subjectAltName = @alt_names

[alt_names]
IP.1 = 20.14.3.12 // My Local IPv4

To create the .key and .crt file, I'm using openssl:

openssl req -x509 -days 36500 -newkey rsa:2048 -keyout key.key -out cert.crt -config san.cnf

I'm also adding the .crt file in Microsoft Management Console, in Root Certification Authorities folder

In my .NET 8 code, I'm adding the following Kestrel tag in appsettings.json:

"Kestrel": {
  "Endpoints": {
    "HttpsInlineCertAndKeyFile": {
      "Url": "https://20.14.3.12:7142",
      "Certificate": {
        "Path": "./Utils/Certificates/cert.crt", // the path is correct
        "KeyPath": "./Utils/Certificates/key.key",
        "Password": "mypassword"
      }
    }
  }
}

My application listen to https://20.14.3.12:7142 and when I try to open swagger, for example, I see the error

NET::ERR_CERT_COMMON_NAME_INVALID

PS: I've tested it using localhost instead of my ip and all works fine, the only change that I've make was to change the IP.1 in .cnf file for DNS.1

Answer 1

My problem was that my IpV4 was changing every time that I generate a new certificate (I don't know why). But the code is right!