diff --git a/config.sample.yaml b/config.sample.yaml
index 6e3e14f..f0aa56a 100644
--- a/config.sample.yaml
+++ b/config.sample.yaml
@@ -1,13 +1,28 @@
 
 
-timeout: 10
+#timeout: 10
+#
+
+# default destination
+# when no SNI name found 
+# or parse TLS HELLO message failed
 default: 127.0.0.1:8443
 
+# the port listen on
+# can specify multiple ports
 listen:
     - 443
     - 9999
 
+# forward rules
+# exact match or wildcard match
 forward_rules:
+    # www.example.com forward to 127.0.0.1:8443
     www.example.com: 127.0.0.1:8443
+
+    # b.example.com forward to 127.0.0.1:8541
     b.example.com: 127.0.0.1:8541
+
+    # forward by SNI, wildcard 
+    # ex: SNI a.example.com from port 9999 forward to a.example.com:443
     "*:9999": "*:443"