$ openssl genrsa -des3 -out macle.key 2048
#Voir aussi "openssl ecparam -genkey" pour Elliptic Curve key
Generating RSA private key, 2048 bit long modulus
................................................+++
...................................................+++
e is 65537 (0x10001)
Enter pass phrase for macle.key:
Verifying - Enter pass phrase for macle.key:

$ openssl req -new -x509 -days 3650 -key macle.key -sha256 -extensions v3_ca -out macle.crt
Error Loading extension section v3_ca

Le problème venait de LibreSSL (pourquoi !?)

Solution 1 (rapide) :

Spécifier le chemin pour prendre l'openssl de la distribution GNU/Linux

/usr/bin/openssl req -new -x509 -days 3650 -key macle.key -sha256 -extensions v3_ca -out macle.crt

Solution 2 (la bonne) :

mv /usr/local/etc/ssl{,.old}
ln -s /etc/ssl /usr/local/etc/ssl

En effet, la conf n'est pas la même

# grep -ri v3_ca /etc/ssl
/etc/ssl/openssl.cnf:x509_extensions	= v3_ca	# The extentions to add to the self signed cert
/etc/ssl/openssl.cnf:[ v3_ca ]

openssl.cnf

[ v3_ca ]
 
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer
basicConstraints = CA:true
 
 
[ req ]
 
x509_extensions = v3_ca # The extentions to add to the self signed cert