1 files changed, 37 insertions, 0 deletions
diff --git a/spec/pt-spec/architecture-overview.md b/spec/pt-spec/architecture-overview.md
new file mode 100644
index 0000000..ef4a6a4
--- /dev/null
+++ b/spec/pt-spec/architecture-overview.md
@@ -0,0 +1,37 @@
+<a id="pt-spec.txt-2"></a>
+
+# Architecture Overview
+
+```text
+     +------------+                    +---------------------------+
+     | Client App +-- Local Loopback --+ PT Client (SOCKS Proxy)   +--+
+     +------------+                    +---------------------------+  |
+                                                                      |
+                 Public Internet (Obfuscated/Transformed traffic) ==> |
+                                                                      |
+     +------------+                    +---------------------------+  |
+     | Server App +-- Local Loopback --+ PT Server (Reverse Proxy) +--+
+     +------------+                    +---------------------------+
+```
+
+On the client's host, the PT Client software exposes a SOCKS proxy
+\[RFC1928\] to the client application, and obfuscates or otherwise
+transforms traffic before forwarding it to the server's host.
+
+On the server's host, the PT Server software exposes a reverse proxy
+that accepts connections from PT Clients, and handles reversing the
+obfuscation/transformation applied to traffic, before forwarding it
+to the actual server software.  An optional lightweight protocol
+exists to facilitate communicating connection meta-data that would
+otherwise be lost such as the source IP address and port
+\[EXTORPORT\].
+
+All PT instances are configured by the respective parent process via
+a set of standardized environment variables (3.2) that are set at
+launch time, and report status information back to the parent via
+writing output in a standardized format to stdout (3.3).
+
+Each invocation of a PT MUST be either a client OR a server.
+
+All PT client forward proxies MUST support either SOCKS 4 or SOCKS 5,
+and SHOULD prefer SOCKS 5 over SOCKS 4.