Homelab: server certificates

In previous log I have introduced my homelab infrastructure.

One of the thing I'm the most bothered with, is the lack of ciphering between my desktop computer (Looping) and my server (Barracuda).

The easiest thing is to generate and expose a server certificate (which will be used to "authenticate" the server and cipher exchanges).

In order to do that we should first create a certificate authority (CA):

##!/usr/bin/env bash
set -xeuo pipefail

CA_DIR=server/ca
REQ_DIR=server/requests

mkdir -p $CA_DIR
touch $CA_DIR/ca.index
openssl rand -hex 16 > $CA_DIR/ca.serial

echo "./$REQ_DIR/ca.conf.dhall \"$CA_DIR\"" | dhall text > "$CA_DIR/ca.conf"

openssl genpkey -algorithm RSA -aes-256-cbc -out "$CA_DIR/ca.key" -pkeyopt rsa_keygen_bits:4096
chmod 400 "$CA_DIR/ca.key"

openssl req -new -out "$CA_DIR/ca.crt" -config "$CA_DIR/ca.conf" -x509 -days 365 -key "$CA_DIR/ca.key"

openssl x509 -in "$CA_DIR/ca.crt" -out "$CA_DIR/ca.pem" -outform PEM

echo "Copy '$CA_DIR/ca.pem' to localhost@/etc/nixos/certificates/barracuda/ca.pem"
echo "To fit with configuration.nix"
echo "pki.certificateFiles = [ ./certificates/barracuda/ca.pem ];"
sudo cp "$CA_DIR/ca.pem" /etc/nixos/certificates/barracuda/ca.pem

Note: in order to generate the configuration files for openssl (I mean, [libressl(https://www.libressl.org/)]), I used dhall-openssl. It's a genius project which abstract the tedious and mysterious world of OpenSSL configuration files you end up copy-pasting from the internet (even if you do it professionally for years).

Which gives:

let openssl =
      https://raw.githubusercontent.com/jvanbruegge/dhall-openssl/master/package.dhall

in  \(caDir : Text) ->
      openssl.mkCaConfig
        openssl.CaConfig::{
        , distinguishedName = openssl.DistinguishedName::{
          , commonName = "Barracuda Root Certificate Authority"
          }
        , allowedHosts = [ "barracuda.local" ]
        , caDir
        }

Simple, straight-to-the-point, genius.

Then, we have to create and sign server certificates:

#!/usr/bin/env bash
set -xeuo pipefail

if [ $# -ne 1 ];
then
  echo "Usage: $0 SERVICE"
  exit 2
fi

SERVICE=$1
CRT_DIR=server/services/$SERVICE
CA_DIR=server/ca
REQ_DIR=server/requests

mkdir -p "$CRT_DIR"

export TEMP_FILE=$(mktemp)
echo "./$REQ_DIR/server.conf.dhall \"$SERVICE\"" | dhall text > "$TEMP_FILE"

# Create a new certificate
openssl req -new -nodes -newkey rsa:4096 -keyout "$CRT_DIR/server.key" -out "$CRT_DIR/server.csr" -config "$TEMP_FILE"

# Sign it with our CA
# TODO add -days 1
openssl ca -config "$CA_DIR/ca.conf" -cert "$CA_DIR/ca.crt" -keyfile "$CA_DIR/ca.key" -out "$CRT_DIR/server.crt" -infiles "$CRT_DIR/server.csr"

TARGET_DIR=/etc/nixos/certificates/servers/$SERVICE
TARGET_LOGIN=black@192.168.0.4
echo "Copy '$CRT_DIR/server.key' and '$CRT_DIR/server.crt' to barracuda@$TARGET_DIR"
ssh $TARGET_LOGIN sudo mkdir -p $TARGET_DIR
scp $CRT_DIR/server.{key,crt} $TARGET_LOGIN:~
ssh $TARGET_LOGIN sudo chown root:root server.key server.crt
ssh $TARGET_LOGIN sudo mv server.key server.crt $TARGET_DIR
ssh $TARGET_LOGIN sudo systemctl restart nginx.service

and the configuration file:

let openssl =
      https://raw.githubusercontent.com/jvanbruegge/dhall-openssl/master/package.dhall

in  \(service : Text) ->
      openssl.mkConfig
        openssl.Config::{
        , distinguishedName = openssl.DistinguishedName::{
          , commonName = "${service}.barracuda.local"
          }
        , altNames = [] : List Text
        }

Then we have to update Barracuda (nginx), configuration:

"withings.barracuda.local" = {
  enableACME = false;
  serverAliases = [ ];
  forceSSL = true;
  sslCertificate = "/etc/nixos/certificates/servers/withings/server.crt";
  sslCertificateKey = "/etc/nixos/certificates/servers/withings/server.key";
  locations."/" = {
    proxyPass = "http://127.0.0.1:5555/";
  };
};

we should have everything working, except, we have to explicitly disable certificate authority check. In order to do that, we should modify Looping (and all clients' configuration) to and the CA to the list of trusted CAs.

security.pki.certificateFiles = [ ./certificates/barracuda/ca.pem ];

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