diff --git a/dap-lib/src/constants.rs b/dap-lib/src/constants.rs
index da56e53..996ccda 100644
--- a/dap-lib/src/constants.rs
+++ b/dap-lib/src/constants.rs
@@ -49,6 +49,9 @@ pub const MAX_CACHE_SIZE: usize = 16384;
 ///////////////////////////////
 // Cannot override below by config.toml
 
+/// HTTP User-Agent
+pub const HTTP_USER_AGENT: &str = "doh-auth-proxy";
+
 // ODoH
 
 /// ODoH config path
diff --git a/dap-lib/src/http_client/http_client_main.rs b/dap-lib/src/http_client/http_client_main.rs
index bd62a96..ab622fc 100644
--- a/dap-lib/src/http_client/http_client_main.rs
+++ b/dap-lib/src/http_client/http_client_main.rs
@@ -1,4 +1,5 @@
 use crate::{
+  constants::HTTP_USER_AGENT,
   error::*,
   trait_resolve_ips::{resolve_ips, ResolveIpResponse, ResolveIps},
 };
@@ -87,7 +88,7 @@ impl HttpClientInner {
     resolved_ips: &[ResolveIpResponse],
   ) -> Result<Self> {
     let mut client = Client::builder()
-      .user_agent(format!("{}/{}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION")))
+      .user_agent(format!("{}/{}", HTTP_USER_AGENT, env!("CARGO_PKG_VERSION")))
       .timeout(timeout_sec)
       .trust_dns(true);