Understanding Direct

The Direct Project makes use of the following concepts and technologies. Please make sure you are familiar with these concepts and that the server(s) you plan to deploy the C# Installation to meet or exceed the "System Requirements" outlined below:
  • PKI Security
    • X509 Certificates
    • CA Certificates, Trust Chains
    • Encryption and Digital Signatures
  • Direct terminology such as
    • Organization Certificate
    • Anchors
  • SMTP/ SMTP Server: How to run and host a public Internet mail server.
  • DNS and how it works
    • MX, ANAME, CERT, CNAME, NS, SOA records
You can learn about these concepts by reading the following documents as well as by leveraging the Internet!

Understanding Secure Email

Reference Implementation Architectural Overview

System Requirements

Used for
Windows Server 2008

Everything :-)
Windows HOT FIX
Large Message Hot Fix
To fix an issue with large messages
.Net Framework 3.5+ with SP1
.Net Framework Download

Smtp Server on Windows 2008
Smtp Server Setup Instructions
  • Runs the Direct Smtp Gateway
  • Free
IIS 7x
Good grasp on IIS Web Site Adminstration
Direct Middle Tier is WCF with HTTP Activation
WCF with HTTP Activation
WCF Setup

SQL Server Express, Sql Server 2008 or equivalent Sql Database
SQL Server 2008 R2 Express Download
  • Used for Storing Domains, Addresses, Certificates, Private Keys, Anchors
SQL Management Studio
SQL Server 2008 Management Studio Express Download
Optional - if NOT already installed
Outbound Firewall Ports:
  • TCP Port 25
  • TCP Port 53
  • UDP Port 53
  • TCP Port 25 used by Smtp Server to send outbound mail
  • TCP Port 53 used by the Gateway to resolve a mail recipient's CERT records from DNS.
  • UDP Port 53 used to resolve standard MX, NS and ANAME records
Inbound Firewall Ports:
  • TCP Port 25
  • TCP Port 53
  • UDP Port 53
  • TCP Port 25 used by Smtp Server to receive incoming mail
  • If running DNS Server:
    • TCP Port 53: Primarily used to receive and respond to requests for CERT records
    • UDP Port 53: Respond to requests for DNS records like MX, NS, ANAME and SOA

System Requirement Notes:
  • Microsoft Server 2012 is not supported at this time. There are plans to support this version in the future.
  • The large message hotfix detailed above is only required on the SMTP server...so if you plan to implement a backend database server separate in your deployment of Direct or if you plan on splitting the Direct roles to separate servers, you will only need to apply the large message hotfix to the server that actually performs the SMTP function.
  • SMTP management tools are installable on IIS 7.X...but those tools are compatability ones through IIS 6.X. Install all components of the IIS 6 Management Compatability Role inside your Windows 2008 Server. For more information, follow the installation portion (first 5 steps) of this technet blog post.