diff --git a/lantern_cli/src/external_index/server.rs b/lantern_cli/src/external_index/server.rs
index d4cc614..569a9ce 100644
--- a/lantern_cli/src/external_index/server.rs
+++ b/lantern_cli/src/external_index/server.rs
@@ -9,7 +9,7 @@ use rustls::{ServerConfig, ServerConnection, StreamOwned};
 use std::cmp;
 use std::fs::{self, File};
 use std::io::{BufReader, Read, Write};
-use std::net::{TcpListener, TcpStream};
+use std::net::{Shutdown, TcpListener, TcpStream};
 use std::os::unix::fs::MetadataExt;
 use std::path::Path;
 use std::sync::mpsc::{self, Receiver, SyncSender};
@@ -26,6 +26,7 @@ const LABEL_SIZE: usize = 8;
 const INTEGER_SIZE: usize = 4;
 const SOCKET_TIMEOUT: u64 = 5;
 pub const PROTOCOL_HEADER_SIZE: usize = 4;
+pub const PROTOCOL_VERSION: u32 = 1;
 pub const SERVER_TYPE: u32 = 0x1; // (0x1: indexing server, 0x2: router server)
 pub const INIT_MSG: u32 = 0x13333337;
 pub const END_MSG: u32 = 0x31333337;
@@ -193,6 +194,7 @@ fn initialize_index(
 ) -> Result<(usize, ThreadSafeIndex), anyhow::Error> {
     let buf = vec![0 as u8; INDEX_HEADER_LENGTH];
     let mut soc_stream = stream.lock().unwrap();
+    soc_stream.write_data(&PROTOCOL_VERSION.to_le_bytes())?;
     soc_stream.write_data(&SERVER_TYPE.to_le_bytes())?;
     match read_frame(&mut soc_stream, buf, INDEX_HEADER_LENGTH, Some(INIT_MSG))? {
         ProtocolMessage::Init(buf) => {
@@ -627,7 +629,8 @@ fn start_status_server(
                 stream.write("Content-Type: application/json\r\n".as_bytes())?;
                 stream.write(format!("Content-Length: {response_len}\r\n\r\n").as_bytes())?;
                 stream.write(response_bytes)?;
-                stream.write(&[0x0D, 0x0A])?;
+                stream.write(&[0x0D, 0x0A])?; // \r\n
+                stream.shutdown(Shutdown::Both)?;
             }
             Err(e) => {
                 logger.error(&format!("Connection error: {e}"));
diff --git a/lantern_cli/tests/external_index_server_test.rs b/lantern_cli/tests/external_index_server_test.rs
index 3d37d39..6e6b2e6 100644
--- a/lantern_cli/tests/external_index_server_test.rs
+++ b/lantern_cli/tests/external_index_server_test.rs
@@ -1,6 +1,8 @@
 use isahc::{ReadResponseExt, Request};
 use lantern_cli::external_index::cli::UMetricKind;
-use lantern_cli::external_index::server::{END_MSG, ERR_MSG, INIT_MSG, PROTOCOL_HEADER_SIZE};
+use lantern_cli::external_index::server::{
+    END_MSG, ERR_MSG, INIT_MSG, PROTOCOL_HEADER_SIZE, PROTOCOL_VERSION,
+};
 use lantern_cli::external_index::{self, cli::IndexServerArgs};
 use rustls::client::danger::{HandshakeSignatureValid, ServerCertVerified, ServerCertVerifier};
 use rustls::pki_types::{CertificateDer, UnixTime};
@@ -142,6 +144,8 @@ async fn test_external_index_server_invalid_header() {
     let mut stream = TcpStream::connect("127.0.0.1:8998").unwrap();
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
     let bytes_written = stream.write(&[0, 1, 1, 1, 1, 1]).unwrap();
     assert_eq!(bytes_written, 6);
@@ -168,6 +172,8 @@ async fn test_external_index_server_short_message() {
     let mut stream = TcpStream::connect("127.0.0.1:8998").unwrap();
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
     let bytes_written = stream.write(&[0, 1]).unwrap();
     assert_eq!(bytes_written, 2);
@@ -228,6 +234,8 @@ async fn test_external_index_server_indexing() {
     let mut stream = TcpStream::connect("127.0.0.1:8998").unwrap();
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
 
     let init_msg = [
@@ -374,6 +382,8 @@ async fn test_external_index_server_indexing_ssl() {
     let mut stream = rustls::Stream::new(&mut conn, &mut sock);
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
 
     let init_msg = [
@@ -485,6 +495,8 @@ async fn test_external_index_server_indexing_scalar_quantization() {
     let mut stream = TcpStream::connect("127.0.0.1:8998").unwrap();
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
     let init_msg = [
         INIT_MSG.to_le_bytes(),
@@ -595,6 +607,8 @@ async fn test_external_index_server_indexing_hamming_distance() {
     let mut stream = TcpStream::connect("127.0.0.1:8998").unwrap();
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
     let init_msg = [
         INIT_MSG.to_le_bytes(),
@@ -712,6 +726,8 @@ async fn test_external_index_server_indexing_pq() {
     let mut stream = TcpStream::connect("127.0.0.1:8998").unwrap();
     let mut uint32_buf = [0; 4];
     stream.read_exact(&mut uint32_buf).unwrap();
+    assert_eq!(u32::from_le_bytes(uint32_buf), PROTOCOL_VERSION);
+    stream.read_exact(&mut uint32_buf).unwrap();
     assert_eq!(u32::from_le_bytes(uint32_buf), 0x1);
     let init_msg = [
         INIT_MSG.to_le_bytes(),