I got an answer to my original question
hopefully it is ok to ask a follow up question by posting another question. From my original question above I was able to decrypt the client pre master secret/key using my private key as it was explained to me using
openssl rsautl -in cpre.key -inkey key.pem -decrypt -out spre.key
This seems pretty straight forward and it created a 48 byte file. I do realize what I am doing is not going to actually decrypt or encrypt the https traffic I am working on this in small steps. The next step from my reading is going to be to generate the master secret/key and from the answer on my previous post it seems I should be able to also do this with openssl which I am struggling a bit here to do this. I've come up with a variation of openssl dgst
echo -n 'value' | openssl dgst -sha256 -mac hmac -macopt hexkey:$(hexkey)
where value is "master secret"+client.random+server.random and hexkey is my decrypted pre master secret from the previous step. Am I doing this step correctly? From the way I understand the RFC since this first time through it produces 32 bytes and the RFC explains it will be 48 bytes. The way I am interpreting the RFC is that I need to take that result and pass it through again which generates an additional 32 bytes of which I take the first 16 and concatenate that on the end of the first 32 to get my 48 bytes for the master secret/key. Am I completely off on this next step after I have decrypted and have the server side pre master key?