any other linux destro can be used to generate private and public keys for pfSence Captive portal
# (Install compiling library Make)
sudo apt-get install make
# (Download the latest OpenSSL 1.0.2g binaries)
wget https://www.openssl.org/source/openssl-1.0.2l.tar.gz
# (Extract the tar ball to the local directory)
tar -xzvf openssl-1.0.2l.tar.gz
# (Enter extracted OpenSSL directory)
cd openssl-1.0.2l
# (Configure binaries for compiling)
./config
# (install configured binaries)
make
cd apps
./openssl genrsa 31 > key.private
./openssl rsa -pubout key.public
cat key.private
cat key.public
Installing old openssl and then creating key less than 30