Make interop server listen on 0.0.0.0.
diff --git a/test/cpp/interop/server.cc b/test/cpp/interop/server.cc
index 5b5c354..8a6be57 100644
--- a/test/cpp/interop/server.cc
+++ b/test/cpp/interop/server.cc
@@ -192,7 +192,7 @@
 
 void RunServer() {
   std::ostringstream server_address;
-  server_address << "localhost:" << FLAGS_port;
+  server_address << "0.0.0.0:" << FLAGS_port;
   TestServiceImpl service;
 
   SimpleRequest request;