Add DTLS docs

README.md

@@ -63,7 +63,7 @@ rust-openssl directory. Then run one of the following commands:
 
 * Windows: `openssl s_server -accept 15418 -www -cert test/cert.pem -key
   test/key.pem > NUL`
-* Linux: `openssl s_server -accept 15418 -www -cert test/cert.pem -key
+* Linux: `openssl s_server -accept 15418 -www -cert test/cert.pem -key \
   test/key.pem >/dev/null`
 
 Then in the original terminal, run `cargo test`. If everything is set up
@@ -71,4 +71,19 @@ correctly, all tests should pass. You might get some warnings in the `openssl
 s_server` window. Those aren't anything to worry about. You can stop the server
 using Control-C.
 
+For DTLS testing each test requires its own instance of OpenSSL's s_server. On
+Linux you can start them like this:
+
+  for port in `seq 15410 15450`; do
+    echo hello | openssl s_server -accept $port -dtls1 -cert test/cert.pem \
+      -key test/key.pem -msg -debug & >/dev/null;
+  done
+
+Note that the test ssl::tests::write::dtlsv1 should be started individually and
+requires an interactive instance:
+
+  openssl s_server -accept 15411 -dtls1 -cert test/cert.pem -key test/key.pem
+
+
+
 [1]: http://slproweb.com/products/Win32OpenSSL.html