diff --git a/config.h b/config.h
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--- /dev/null
+++ b/config.h
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+/*
+ * Copyright 2011 Daniel Drown
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * config.h - configuration settings
+ */
+#ifndef __CONFIG_H__
+#define __CONFIG_H__
+
+#include <netinet/in.h>
+#include <sys/system_properties.h>
+
+#define DEFAULT_IPV4_LOCAL_SUBNET "192.168.255.1"
+#define DEFAULT_DNS64_DETECTION_HOSTNAME "ipv4.google.com"
+
+struct clat_config {
+  int16_t mtu, ipv4mtu;
+  struct in6_addr ipv6_local_subnet;
+  struct in6_addr ipv6_host_id;
+  struct in_addr ipv4_local_subnet;
+  struct in6_addr plat_subnet;
+  char default_pdp_interface[PROP_VALUE_MAX];
+  char *plat_from_dns64_hostname;
+};
+
+extern struct clat_config Global_Clatd_Config;
+
+int read_config(const char *file, const char *uplink_interface, const char *plat_prefix);
+void config_generate_local_ipv6_subnet(struct in6_addr *interface_ip);
+
+#endif /* __CONFIG_H__ */