anchor.diff:  , iproute2
   , lzo
   , openssl
  +, openssl_1_1
   , pam
   , useSystemd ? stdenv.isLinux
   , systemd
  
positive.code: let
    inherit (lib) versionOlder optional optionals optionalString;
  
    generic = { version, sha256 }:
      let
        withIpRoute = stdenv.isLinux && (versionOlder version "2.5.4");
      in
  
negative.code:   openvpn_24 = generic {
      version = "2.4.12";
      sha256 = "1vjx82nlkxrgzfiwvmmlnz8ids5m2fiqz7scy1smh3j9jnf2v5b6";
      extraBuildInputs = [ openssl_1_1 ];
    };
  
    openvpn = generic {
      version = "2.5.6";
      sha256 = "0gdd88rcan9vfiwkzsqn6fxxdim7kb1bsxrcra59c5xksprpwfik";
      extraBuildInputs = [ openssl ];
    };
  }
  