diff --git a/server_results.csv b/server_results.csv
new file mode 100644
index 0000000..9bfb416
--- /dev/null
+++ b/server_results.csv
@@ -0,0 +1,5 @@
+timestamp,host,port,protocol,direction,duration_s,tx_avg_mbps,rx_avg_mbps,tx_bytes,rx_bytes,lost_packets,auth_type
+1775024492,172.16.81.1,59260,TCP,BOTH,57,9.97,2.98,71008256,21227792,0,ecsrp5
+1775024501,172.16.81.1,59300,TCP,TX,9,42.41,0.00,47710208,0,0,ecsrp5
+1775024526,172.16.81.1,59340,TCP,RX,442,0.00,2.46,0,136015152,0,ecsrp5
+1775024533,172.16.81.1,59380,UDP,RX,6,0.00,59.49,0,44620736,16013664,ecsrp5
diff --git a/tests/full_integration_test.rs b/tests/full_integration_test.rs
new file mode 100644
index 0000000..96f4bd5
--- /dev/null
+++ b/tests/full_integration_test.rs
@@ -0,0 +1,333 @@
+//! Comprehensive integration tests covering all modes, protocols, and output formats.
+//! Each test starts a server, runs a client, verifies data flows, and checks CSV/stats.
+
+use std::net::UdpSocket as StdUdpSocket;
+use std::sync::atomic::Ordering;
+use std::time::Duration;
+
+const BASE_PORT: u16 = 14000;
+
+// --- Helpers ---
+
+async fn start_server(port: u16, ecsrp5: bool) {
+    let auth_user = Some("testuser".into());
+    let auth_pass = Some("testpass".into());
+    tokio::spawn(async move {
+        let _ = btest_rs::server::run_server(
+            port, auth_user, auth_pass, ecsrp5,
+            Some("127.0.0.1".into()), None,
+        ).await;
+    });
+    tokio::time::sleep(Duration::from_millis(200)).await;
+}
+
+async fn start_server_noauth(port: u16) {
+    tokio::spawn(async move {
+        let _ = btest_rs::server::run_server(
+            port, None, None, false,
+            Some("127.0.0.1".into()), None,
+        ).await;
+    });
+    tokio::time::sleep(Duration::from_millis(200)).await;
+}
+
+async fn start_server_v6(port: u16) {
+    tokio::spawn(async move {
+        let _ = btest_rs::server::run_server(
+            port, None, None, false,
+            None, Some("::1".into()),
+        ).await;
+    });
+    tokio::time::sleep(Duration::from_millis(200)).await;
+}
+
+async fn run_client_test(
+    host: &str, port: u16, transmit: bool, receive: bool, udp: bool,
+    user: Option<&str>, pass: Option<&str>,
+) -> (u64, u64, u64, u32) {
+    let direction = match (transmit, receive) {
+        (true, false) => btest_rs::protocol::CMD_DIR_RX,
+        (false, true) => btest_rs::protocol::CMD_DIR_TX,
+        (true, true) => btest_rs::protocol::CMD_DIR_BOTH,
+        _ => panic!("must specify direction"),
+    };
+    let state = btest_rs::bandwidth::BandwidthState::new();
+    let state_clone = state.clone();
+
+    let host = host.to_string();
+    let user = user.map(String::from);
+    let pass = pass.map(String::from);
+
+    let handle = tokio::spawn(async move {
+        btest_rs::client::run_client(
+            &host, port, direction, udp,
+            0, 0, user, pass, false, state_clone,
+        ).await
+    });
+
+    tokio::time::sleep(Duration::from_secs(2)).await;
+    state.running.store(false, Ordering::SeqCst);
+    tokio::time::sleep(Duration::from_millis(500)).await;
+    handle.abort();
+
+    state.summary()
+}
+
+// --- TCP IPv4 Tests ---
+
+#[tokio::test]
+async fn test_tcp4_receive() {
+    let port = BASE_PORT;
+    start_server_noauth(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("127.0.0.1", port, false, true, false, None, None).await;
+    assert!(_rx > 0, "TCP4 receive: expected rx > 0, got {}", _rx);
+    assert!(_intervals > 0, "TCP4 receive: expected intervals > 0");
+}
+
+#[tokio::test]
+async fn test_tcp4_send() {
+    let port = BASE_PORT + 1;
+    start_server_noauth(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("127.0.0.1", port, true, false, false, None, None).await;
+    assert!(_tx > 0, "TCP4 send: expected tx > 0, got {}", _tx);
+    assert!(_intervals > 0, "TCP4 send: expected intervals > 0");
+}
+
+#[tokio::test]
+async fn test_tcp4_both() {
+    let port = BASE_PORT + 2;
+    start_server_noauth(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("127.0.0.1", port, true, true, false, None, None).await;
+    assert!(_tx > 0, "TCP4 both: expected tx > 0, got {}", _tx);
+    assert!(_rx > 0, "TCP4 both: expected rx > 0, got {}", _rx);
+}
+
+// --- UDP IPv4 Tests ---
+
+#[tokio::test]
+async fn test_udp4_receive() {
+    let port = BASE_PORT + 3;
+    start_server_noauth(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("127.0.0.1", port, false, true, true, None, None).await;
+    assert!(_rx > 0, "UDP4 receive: expected rx > 0, got {}", _rx);
+}
+
+#[tokio::test]
+async fn test_udp4_send() {
+    let port = BASE_PORT + 4;
+    start_server_noauth(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("127.0.0.1", port, true, false, true, None, None).await;
+    assert!(_tx > 0, "UDP4 send: expected tx > 0, got {}", _tx);
+}
+
+#[tokio::test]
+async fn test_udp4_both() {
+    let port = BASE_PORT + 5;
+    start_server_noauth(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("127.0.0.1", port, true, true, true, None, None).await;
+    assert!(_tx > 0, "UDP4 both: expected tx > 0, got {}", _tx);
+    assert!(_rx > 0, "UDP4 both: expected rx > 0, got {}", _rx);
+}
+
+// --- TCP IPv6 Tests ---
+
+#[tokio::test]
+async fn test_tcp6_receive() {
+    let port = BASE_PORT + 6;
+    start_server_v6(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("::1", port, false, true, false, None, None).await;
+    assert!(_rx > 0, "TCP6 receive: expected rx > 0, got {}", _rx);
+}
+
+#[tokio::test]
+async fn test_tcp6_send() {
+    let port = BASE_PORT + 7;
+    start_server_v6(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("::1", port, true, false, false, None, None).await;
+    assert!(_tx > 0, "TCP6 send: expected tx > 0, got {}", _tx);
+}
+
+#[tokio::test]
+async fn test_tcp6_both() {
+    let port = BASE_PORT + 8;
+    start_server_v6(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("::1", port, true, true, false, None, None).await;
+    assert!(_tx > 0, "TCP6 both: expected tx > 0, got {}", _tx);
+    assert!(_rx > 0, "TCP6 both: expected rx > 0, got {}", _rx);
+}
+
+// --- UDP IPv6 Tests (loopback, no ENOBUFS issues) ---
+
+#[tokio::test]
+async fn test_udp6_receive() {
+    let port = BASE_PORT + 9;
+    start_server_v6(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("::1", port, false, true, true, None, None).await;
+    assert!(_rx > 0, "UDP6 receive: expected rx > 0, got {}", _rx);
+}
+
+#[tokio::test]
+async fn test_udp6_send() {
+    let port = BASE_PORT + 10;
+    start_server_v6(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("::1", port, true, false, true, None, None).await;
+    assert!(_tx > 0, "UDP6 send: expected tx > 0, got {}", _tx);
+}
+
+#[tokio::test]
+async fn test_udp6_both() {
+    let port = BASE_PORT + 11;
+    start_server_v6(port).await;
+    let (_tx, _rx, _, _intervals) = run_client_test("::1", port, true, true, true, None, None).await;
+    assert!(_tx > 0, "UDP6 both: expected tx > 0, got {}", _tx);
+    assert!(_rx > 0, "UDP6 both: expected rx > 0, got {}", _rx);
+}
+
+// --- Authentication Tests ---
+
+#[tokio::test]
+async fn test_md5_auth_works() {
+    let port = BASE_PORT + 12;
+    start_server(port, false).await;
+    let (_tx, _rx, _, _) = run_client_test(
+        "127.0.0.1", port, false, true, false,
+        Some("testuser"), Some("testpass"),
+    ).await;
+    assert!(_rx > 0, "MD5 auth: expected data flow");
+}
+
+#[tokio::test]
+async fn test_ecsrp5_auth_works() {
+    let port = BASE_PORT + 13;
+    start_server(port, true).await;
+    let (_tx, _rx, _, _) = run_client_test(
+        "127.0.0.1", port, false, true, false,
+        Some("testuser"), Some("testpass"),
+    ).await;
+    assert!(_rx > 0, "EC-SRP5 auth: expected data flow");
+}
+
+#[tokio::test]
+async fn test_ecsrp5_wrong_password() {
+    let port = BASE_PORT + 14;
+    start_server(port, true).await;
+    let state = btest_rs::bandwidth::BandwidthState::new();
+    let result = btest_rs::client::run_client(
+        "127.0.0.1", port,
+        btest_rs::protocol::CMD_DIR_TX,
+        false, 0, 0,
+        Some("testuser".into()), Some("wrongpass".into()),
+        false, state,
+    ).await;
+    assert!(result.is_err(), "Wrong password should fail");
+}
+
+// --- CSV Output Tests ---
+
+#[tokio::test]
+async fn test_csv_created_client() {
+    let port = BASE_PORT + 15;
+    start_server_noauth(port).await;
+
+    let csv_path = format!("/tmp/btest_test_csv_{}.csv", port);
+    let _ = std::fs::remove_file(&csv_path);
+
+    // Initialize CSV
+    btest_rs::csv_output::init(&csv_path).unwrap();
+
+    let (tx, rx, lost, intervals) = run_client_test(
+        "127.0.0.1", port, false, true, false, None, None,
+    ).await;
+
+    // Write result like main.rs does
+    btest_rs::csv_output::write_result(
+        "127.0.0.1", port, "TCP", "receive",
+        2, tx, rx, lost, "none",
+    );
+
+    // Verify CSV exists and has data
+    let content = std::fs::read_to_string(&csv_path).unwrap();
+    let lines: Vec<&str> = content.lines().collect();
+    assert!(lines.len() >= 2, "CSV should have header + at least 1 row, got {} lines", lines.len());
+    assert!(lines[0].starts_with("timestamp,"), "CSV header missing");
+    assert!(lines[1].contains("TCP"), "CSV row should contain protocol");
+    assert!(!lines[1].contains(",0,0,0,"), "CSV should have non-zero bytes");
+
+    let _ = std::fs::remove_file(&csv_path);
+}
+
+#[tokio::test]
+async fn test_csv_created_server() {
+    let port = BASE_PORT + 16;
+    let csv_path = format!("/tmp/btest_test_server_csv_{}.csv", port);
+    let _ = std::fs::remove_file(&csv_path);
+
+    btest_rs::csv_output::init(&csv_path).unwrap();
+    start_server_noauth(port).await;
+
+    let _ = run_client_test("127.0.0.1", port, false, true, false, None, None).await;
+    tokio::time::sleep(Duration::from_millis(500)).await;
+
+    let content = std::fs::read_to_string(&csv_path).unwrap_or_default();
+    let lines: Vec<&str> = content.lines().collect();
+    assert!(lines.len() >= 2, "Server CSV should have header + rows, got {}", lines.len());
+
+    let _ = std::fs::remove_file(&csv_path);
+}
+
+// --- Syslog Tests ---
+
+#[tokio::test]
+async fn test_syslog_emits_events() {
+    // Bind a local UDP socket to receive syslog messages
+    let syslog_sock = StdUdpSocket::bind("127.0.0.1:0").unwrap();
+    let syslog_addr = syslog_sock.local_addr().unwrap();
+    syslog_sock.set_nonblocking(true).unwrap();
+
+    // Initialize syslog to our test socket
+    btest_rs::syslog_logger::init(&syslog_addr.to_string()).unwrap();
+
+    let port = BASE_PORT + 17;
+    start_server_noauth(port).await;
+
+    let _ = run_client_test("127.0.0.1", port, false, true, false, None, None).await;
+    tokio::time::sleep(Duration::from_millis(500)).await;
+
+    // Read all syslog messages
+    let mut messages = Vec::new();
+    let mut buf = [0u8; 4096];
+    loop {
+        match syslog_sock.recv(&mut buf) {
+            Ok(n) => messages.push(String::from_utf8_lossy(&buf[..n]).to_string()),
+            Err(_) => break,
+        }
+    }
+
+    let all = messages.join("\n");
+    assert!(all.contains("AUTH_SUCCESS") || all.contains("TEST_START"),
+        "Syslog should contain auth or test events, got: {}", all);
+    assert!(all.contains("TEST_START"), "Syslog should contain TEST_START");
+    assert!(all.contains("TEST_END"), "Syslog should contain TEST_END");
+}
+
+// --- Bandwidth State Tests ---
+
+#[tokio::test]
+async fn test_bandwidth_state_record_interval() {
+    let state = btest_rs::bandwidth::BandwidthState::new();
+    state.record_interval(1000, 2000, 5);
+    state.record_interval(3000, 4000, 10);
+    let (tx, rx, lost, intervals) = state.summary();
+    assert_eq!(tx, 4000);
+    assert_eq!(rx, 6000);
+    assert_eq!(lost, 15);
+    assert_eq!(intervals, 2);
+}
+
+#[tokio::test]
+async fn test_bandwidth_state_running_flag() {
+    let state = btest_rs::bandwidth::BandwidthState::new();
+    assert!(state.running.load(Ordering::Relaxed));
+    state.running.store(false, Ordering::SeqCst);
+    assert!(!state.running.load(Ordering::Relaxed));
+}