diff --git a/docs/sources/reference/commandline/cli.md b/docs/sources/reference/commandline/cli.md
index ef30113882..9c313b0c78 100644
--- a/docs/sources/reference/commandline/cli.md
+++ b/docs/sources/reference/commandline/cli.md
@@ -764,9 +764,25 @@ log entry.
 
 ## port
 
-    Usage: docker port CONTAINER PRIVATE_PORT
+    Usage: docker port CONTAINER [PRIVATE_PORT[/PROTO]]
 
-    Lookup the public-facing port that is NAT-ed to PRIVATE_PORT
+    List port mappings for the CONTAINER, or lookup the public-facing port that is NAT-ed to the PRIVATE_PORT
+
+You can find out all the ports mapped by not specifying a `PRIVATE_PORT`, or
+just a specific mapping:
+
+    $ docker ps test
+    CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                                            NAMES
+    b650456536c7        busybox:latest      top                 54 minutes ago      Up 54 minutes       0.0.0.0:1234->9876/tcp, 0.0.0.0:4321->7890/tcp   test
+    $ docker port test
+    7890/tcp -> 0.0.0.0:4321
+    9876/tcp -> 0.0.0.0:1234
+    $ docker port test 7890/tcp
+    0.0.0.0:4321
+    $ docker port test 7890/udp
+    2014/06/24 11:53:36 Error: No public port '7890/udp' published for test
+    $ docker port test 7890
+    0.0.0.0:4321
 
 ## pause