Bump to CentOS 7.4.1708

Change-Id: Ifa836be578b9ad1d68bcc16eae7a0ca15cc3d9de
diff --git a/docker/centos7/Makefile b/docker/centos7/Makefile
index 3bcf250..a4da8c9 100644
--- a/docker/centos7/Makefile
+++ b/docker/centos7/Makefile
@@ -13,7 +13,7 @@
 # End of the variables that can be customized
 
 define DOCKERFILE
-FROM centos:7.3.1611
+FROM centos:7.4.1708
 MAINTAINER $(VENDOR)
 
 # Allow remote connectivity and sudo