diff --git a/crates/tsunagi-cli/src/main.rs b/crates/tsunagi-cli/src/main.rs
index 4f4c264..8060cb0 100644
--- a/crates/tsunagi-cli/src/main.rs
+++ b/crates/tsunagi-cli/src/main.rs
@@ -4078,6 +4078,8 @@ async fn build_report(
                             handshake_secs_ago: tunnel.health.since_handshake.map(|s| s.as_secs()),
                             tx_packets: tunnel.stats.tx_packets,
                             rx_packets: tunnel.stats.rx_packets,
+                            tx_bytes: tunnel.stats.tx_bytes,
+                            rx_bytes: tunnel.stats.rx_bytes,
                             dropped: tunnel.stats.dropped_wrong_source
                                 + tunnel.stats.dropped_oversize,
                             protocol_errors: tunnel.stats.protocol_errors,
@@ -4096,6 +4098,8 @@ async fn build_report(
                             handshake_secs_ago: Some(tcp_tls.uptime_secs),
                             tx_packets: tcp_tls.tx_packets,
                             rx_packets: tcp_tls.rx_packets,
+                            tx_bytes: tcp_tls.tx_bytes,
+                            rx_bytes: tcp_tls.rx_bytes,
                             dropped: tcp_tls.dropped,
                             protocol_errors: 0,
                             path: tcp_tls.path.clone(),
@@ -4114,6 +4118,8 @@ async fn build_report(
                             handshake_secs_ago: tunnel.health.since_handshake.map(|s| s.as_secs()),
                             tx_packets: tunnel.stats.tx_packets,
                             rx_packets: tunnel.stats.rx_packets,
+                            tx_bytes: tunnel.stats.tx_bytes,
+                            rx_bytes: tunnel.stats.rx_bytes,
                             dropped: tunnel.stats.dropped_wrong_source
                                 + tunnel.stats.dropped_oversize,
                             protocol_errors: tunnel.stats.protocol_errors,
@@ -4131,6 +4137,8 @@ async fn build_report(
                             handshake_secs_ago: None,
                             tx_packets: 0,
                             rx_packets: 0,
+                            tx_bytes: 0,
+                            rx_bytes: 0,
                             dropped: 0,
                             protocol_errors: 0,
                             path: "no data link".into(),
@@ -4147,6 +4155,8 @@ async fn build_report(
                             handshake_secs_ago: None,
                             tx_packets: 0,
                             rx_packets: 0,
+                            tx_bytes: 0,
+                            rx_bytes: 0,
                             dropped: 0,
                             protocol_errors: 0,
                             path: "no data link".into(),
diff --git a/crates/tsunagi/src/dataplane/tunnel.rs b/crates/tsunagi/src/dataplane/tunnel.rs
index 6da28ad..41a5597 100644
--- a/crates/tsunagi/src/dataplane/tunnel.rs
+++ b/crates/tsunagi/src/dataplane/tunnel.rs
@@ -83,6 +83,8 @@ struct TunnelPeerState {
     link: SharedLink,
     tx_packets: AtomicU64,
     rx_packets: AtomicU64,
+    tx_bytes: AtomicU64,
+    rx_bytes: AtomicU64,
     dropped: AtomicU64,
     established_at: std::time::Instant,
 }
@@ -100,6 +102,10 @@ pub struct TunnelPeerReport {
     pub tx_packets: u64,
     /// Packets successfully received and decrypted.
     pub rx_packets: u64,
+    /// Plaintext bytes successfully encrypted and sent.
+    pub tx_bytes: u64,
+    /// Plaintext bytes successfully received and decrypted.
+    pub rx_bytes: u64,
     /// Packets dropped due to encryption/decryption/send failures.
     pub dropped: u64,
     /// Uptime in seconds since the data link was established.
@@ -145,6 +151,8 @@ impl<C: TunnelCodec> GenericTunnelPlugin<C> {
                 path: state.link.path_description(),
                 tx_packets: state.tx_packets.load(Ordering::Relaxed),
                 rx_packets: state.rx_packets.load(Ordering::Relaxed),
+                tx_bytes: state.tx_bytes.load(Ordering::Relaxed),
+                rx_bytes: state.rx_bytes.load(Ordering::Relaxed),
                 dropped: state.dropped.load(Ordering::Relaxed),
                 uptime_secs: state.established_at.elapsed().as_secs(),
             })
@@ -223,6 +231,9 @@ impl<C: TunnelCodec> IpPlugin for GenericTunnelPlugin<C> {
             Ok(ciphertext) => {
                 if state.link.send(ciphertext).is_ok() {
                     state.tx_packets.fetch_add(1, Ordering::Relaxed);
+                    state
+                        .tx_bytes
+                        .fetch_add(packet.len() as u64, Ordering::Relaxed);
                     true
                 } else {
                     state.dropped.fetch_add(1, Ordering::Relaxed);
@@ -242,6 +253,8 @@ impl<C: TunnelCodec> IpPlugin for GenericTunnelPlugin<C> {
             link: Arc::clone(&link),
             tx_packets: AtomicU64::new(0),
             rx_packets: AtomicU64::new(0),
+            tx_bytes: AtomicU64::new(0),
+            rx_bytes: AtomicU64::new(0),
             dropped: AtomicU64::new(0),
             established_at: std::time::Instant::now(),
         });
@@ -268,6 +281,9 @@ impl<C: TunnelCodec> IpPlugin for GenericTunnelPlugin<C> {
                 match codec.decrypt(network, peer, &payload) {
                     Ok(packet) => {
                         rx_state.rx_packets.fetch_add(1, Ordering::Relaxed);
+                        rx_state
+                            .rx_bytes
+                            .fetch_add(packet.len() as u64, Ordering::Relaxed);
                         if let Some(ref sink) = sink {
                             sink.deliver(network, peer, packet).await;
                         }
diff --git a/crates/tsunagi/src/ipc/mod.rs b/crates/tsunagi/src/ipc/mod.rs
index 70d6d9c..fcae9cd 100644
--- a/crates/tsunagi/src/ipc/mod.rs
+++ b/crates/tsunagi/src/ipc/mod.rs
@@ -472,6 +472,10 @@ pub struct OverlayPeerReport {
     pub tx_packets: u64,
     /// Packets decrypted from this peer.
     pub rx_packets: u64,
+    /// Plaintext bytes encrypted and sent to this peer.
+    pub tx_bytes: u64,
+    /// Plaintext bytes decrypted from this peer.
+    pub rx_bytes: u64,
     /// Data packets dropped: wrong source address, or too large for the path.
     pub dropped: u64,
     /// WireGuard protocol errors.
@@ -605,7 +609,7 @@ pub const EXCHANGE_TIMEOUT: Duration = Duration::from_secs(5);
 ///
 /// Bump it whenever [`Request`], [`Response`] or anything they contain
 /// changes shape.
-pub const CONTROL_PROTOCOL: u32 = u32::from_be_bytes([b'T', b'S', b'N', 15]);
+pub const CONTROL_PROTOCOL: u32 = u32::from_be_bytes([b'T', b'S', b'N', 16]);
 
 /// Reads one request off an accepted stream, answers it, writes the response.
 ///