diff --git a/ddob/README.md b/ddob/README.md
new file mode 100644
index 0000000..6060e9c
--- /dev/null
+++ b/ddob/README.md
@@ -0,0 +1,7 @@
+# DDNS over BearyChat
+
+## Usage
+
+```
+$ ./ddob
+```
diff --git a/ddob/cmd/ddob/main.go b/ddob/cmd/ddob/main.go
new file mode 100644
index 0000000..71acb73
--- /dev/null
+++ b/ddob/cmd/ddob/main.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"regexp"
+
+	"github.com/bearyinnovative/radagast/bearychat"
+	"github.com/bearyinnovative/radagast/config"
+	"github.com/bearyinnovative/radagast/ddob"
+)
+
+func main() {
+	ctx := context.Background()
+	ctx = config.MustMakeContext(ctx, "./radagast.toml")
+	ctx = bearychat.MustMakeContext(ctx)
+
+	config := config.FromContext(ctx)
+
+	p := regexp.MustCompile(config.Get("ddob.pattern").String())
+	addrs, err := ddob.ListInterfaceAddrs(p)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if len(addrs) < 1 {
+		log.Fatalf("no addrs returned")
+	}
+
+	bearychat.SendToVchannel(
+		ctx,
+		bearychat.RTMClientFromContext(ctx),
+		bearychat.RTMMessage{
+			Text:       fmt.Sprintf("`ddob` 我的 IP 是 `%s`", addrs[0]),
+			VchannelId: config.Get("ddob.bearychat-vchannel-id").String(),
+		},
+	)
+}
diff --git a/ddob/interfaces.go b/ddob/interfaces.go
new file mode 100644
index 0000000..1191ad3
--- /dev/null
+++ b/ddob/interfaces.go
@@ -0,0 +1,30 @@
+package ddob
+
+import (
+	"net"
+	"regexp"
+)
+
+func ListInterfaceAddrs(namePattern *regexp.Regexp) (addrs []net.Addr, err error) {
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, inter := range interfaces {
+		if !namePattern.MatchString(inter.Name) {
+			continue
+		}
+
+		interfaceAddrs, err := inter.Addrs()
+		if err != nil {
+			return nil, err
+		}
+
+		for _, addr := range interfaceAddrs {
+			addrs = append(addrs, addr)
+		}
+	}
+
+	return
+}