diff --git a/hswaw/checkinator/at/tracker.proto b/hswaw/checkinator/at/tracker.proto
new file mode 100644
index 0000000..7db4e5c
--- /dev/null
+++ b/hswaw/checkinator/at/tracker.proto
@@ -0,0 +1,31 @@
+syntax = "proto3";
+
+service DhcpTracker {
+  /* get list of clients detected in LAN network */
+  rpc GetClients (ClientsRequest) returns (DhcpClients) {};
+
+  /* get Layer 2 addess (MAC) for LAN ip address (v4 or v6) */
+  rpc GetHwAddr (HwAddrRequest) returns (HwAddrResponse) {};
+}
+
+message ClientsRequest {
+}
+
+message DhcpClient {
+  bytes hw_address = 1;
+  string last_seen = 2;
+  string client_hostname = 3;
+  string ip_address = 4;
+}
+
+message DhcpClients {
+  repeated DhcpClient clients = 1;
+}
+
+message HwAddrRequest {
+  string ip_address = 1; // IPv4 or IPv6 address
+}
+
+message HwAddrResponse {
+  bytes hw_address = 1; // MAC address
+}