Trouble getting a self-signed cert working in Postman - apache

Question

I'm finally getting into using SSL on my personal sites, so I started by trying to make a multi-domain self signed cert for my local development (to handle api.mydomain.local, www.mydomain.local, and mydomain.local). I don't know if this was my first mistake, but...
As I couldn't find a single encompassing guide, I started by using two tutorials (from EasyEngine and DeveloperSide) to create my cert and install it on my host (Win10). I then used a DigitalOcean guide to figure out how to setup my Apache on my dev server (a Ubuntu VM); up to there, no big trouble, other than some minor issues caused by working from multiple guides at the same time.
I go ahead and try to hit my api in Chrome, it gives me an untrusted certificate value as expected, I pass and it works. As far as I know, this means the cert worked? However, when I try to hit my api in Postman, I get an error that indicates it can't accept an untrusted cert, which is fine, as it has a tutorial on how to fix that. However, it still doesn't work. I can't figure out what else to do to fix this, am I on the right track? Is my cert completely borked? Did I make a core mistake in trying to do a multi-domain cert?
One thing I did notice is that in the Dev Tools security tab, it says
Subject Alternative Name missing
So I'm not sure if that means my alt names aren't working, but if they weren't, it wouldn't try to load the certificate when I hit it in Chrome, right?

Answer 1

I had a similar issue while writing an article for my website on SSL certificates. So i wrote shell script for the same
#!/bin/bash
CERT_COMPANY_NAME=${CERT_COMPANY_NAME:=Tarun Lalwani}
CERT_COUNTRY=${CERT_COUNTRY:=IN}
CERT_STATE=${CERT_STATE:=DELHI}
CERT_CITY=${CERT_CITY:=DELHI}
CERT_DIR=${CERT_DIR:=certs}
ROOT_CERT=${ROOT_CERT:=rootCA.pem}
ROOT_CERT_KEY=${ROOT_CERT_KEY:=rootCA.key.pem}
# make directories to work from
mkdir -p $CERT_DIR
create_root_cert(){
# Create your very own Root Certificate Authority
openssl genrsa \
-out $CERT_DIR/$ROOT_CERT_KEY \
2048
# Self-sign your Root Certificate Authority
# Since this is private, the details can be as bogus as you like
openssl req \
-x509 \
-new \
-nodes \
-key ${CERT_DIR}/$ROOT_CERT_KEY \
-days 1024 \
-out ${CERT_DIR}/$ROOT_CERT \
-subj "/C=$CERT_COUNTRY/ST=$CERT_STATE/L=$CERT_CITY/O=$CERT_COMPANY_NAME Signing Authority/CN=$CERT_COMPANY_NAME Signing Authority"
}
create_domain_cert()
{
local FQDN=$1
local FILENAME=${FQDN/\*/wild}
# Create a Device Certificate for each domain,
# such as example.com, *.example.com, awesome.example.com
# NOTE: You MUST match CN to the domain name or ip address you want to use
openssl genrsa \
-out $CERT_DIR/${FILENAME}.key \
2048
# Create a request from your Device, which your Root CA will sign
if [[ ! -z "${SAN}" ]]; then
openssl req -new \
-key ${CERT_DIR}/${FILENAME}.key \
-out ${CERT_DIR}/${FILENAME}.csr \
-subj "/C=${CERT_COUNTRY}/ST=${CERT_STATE}/L=${CERT_CITY}/O=$CERT_COMPANY_NAME/CN=${FQDN}" \
-reqexts san_env -config <(cat /etc/ssl/openssl.cnf <(cat ./openssl-san.cnf))
else
openssl req -new \
-key ${CERT_DIR}/${FILENAME}.key \
-out ${CERT_DIR}/${FILENAME}.csr \
-subj "/C=${CERT_COUNTRY}/ST=${CERT_STATE}/L=${CERT_CITY}/O=$CERT_COMPANY_NAME/CN=${FQDN}"
fi
# Sign the request from Device with your Root CA
if [[ ! -z "${SAN}" ]]; then
openssl x509 \
-sha256 \
-req -in $CERT_DIR/${FILENAME}.csr \
-CA $CERT_DIR/$ROOT_CERT \
-CAkey $CERT_DIR/$ROOT_CERT_KEY \
-CAcreateserial \
-out $CERT_DIR/${FILENAME}.crt \
-days 500 \
-extensions san_env \
-extfile openssl-san.cnf
else
openssl x509 \
-sha256 \
-req -in $CERT_DIR/${FILENAME}.csr \
-CA $CERT_DIR/$ROOT_CERT \
-CAkey $CERT_DIR/$ROOT_CERT_KEY \
-CAcreateserial \
-out $CERT_DIR/${FILENAME}.crt \
-days 500
fi
}
METHOD=$1
ARGS=${*:2}
echo "Called with $METHOD and $ARGS"
if [ -z "${METHOD}" ]; then
echo "Usage ./sslcerts.sh [create_root_cert|create_domain_cert] <args>"
echo "Below are the environment variabls you can use:"
echo "CERT_COMPANY_NAME=Company Name"
echo "CERT_COUNTRY=Country"
echo "CERT_STATE=State"
echo "CERT_CITY=City"
echo "CERT_DIR=Directory where certificate needs to be genereated"
echo "ROOT_CERT=Name of the root cert"
echo "ROOT_CERT_KEY=Name of root certificate key"
else
${METHOD} ${ARGS}
fi
You can change the environment variables on the TOP and generate a self-signed certificate using below
$ SAN=DNS.1:*.tarunlalwani.com,DNS.2:tarunlalwani.com ./sslcerts.sh create_domain_cert '*.tarunlalwani.com'
Edit 1
Earlier browsers use to rely on FQDN, but now some of them have started using SAN which is "Subject Alternative Name". Generally openssl doesn't come up v3 extensions configured. SAN is a part of the v3 extensions. So when you generated a self signed certificated it has the correct FQDN (Full qualified domain name) but not SAN. Chrome will show error for these certificates but you will see firefox working fine.
PS: Taken from article http://tarunlalwani.com/post/self-signed-certificates-trusting-them/