diff --git a/README.md b/README.md
index 1545ef6..445b948 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,8 @@ from VDDK 8 NBD traffic; see `docs/`.
 
 ## Status
 
-Implemented against vCenter 8 / ESXi 8, transport `nbd`:
+Implemented against vCenter 8 / ESXi 8. Default transport is `nbdssl`
+(`nbd` is still available):
 
 - `VixDiskLib_ConnectEx` (UID credentials)
 - `VixDiskLib_Open` (datastore path, read-only or read-write)
@@ -45,7 +46,7 @@ with handle.connect(
         username="administrator@vsphere.local",
         password="secret",
         vmx_spec="moref=vm-1234",
-        transport_modes="nbd",
+        transport_modes="nbdssl",
         read_only=False) as conn:
     with handle.open(conn, "[datastore] vm/vm.vmdk", flags=0) as disk:
         handle.write(disk, 0, 1, buf)
diff --git a/docs/nfc_auth.md b/docs/nfc_auth.md
index ff7c569..4244e37 100644
--- a/docs/nfc_auth.md
+++ b/docs/nfc_auth.md
@@ -25,16 +25,17 @@ password to ESXi port 902. It:
 3. Connects to the ESXi **authd** daemon on TCP 902, upgrades to TLS,
    and presents that ticket.
 
-| VDDK call                         | What actually happens                                      |
-| --------------------------------- | ---------------------------------------------------------- |
-| `VixDiskLib_InitEx`               | Load plugins, SSL, logging                                 |
-| `VixDiskLib_ConnectEx`            | SOAP `SessionManager.Login` to vCenter                     |
-| `VixDiskLib_Open` (read-only)     | `NfcGetVmFiles` ticket, then authd handshake, then NFC I/O |
-| `VixDiskLib_Open` (read-write)    | `NfcRandomAccessOpenDisk` ticket (disk key + host)         |
-| `transport_modes="nbd"`           | NBD over NFC (`vpxa-nfc://...@esxi:902`)                   |
-| `vmxSpec=moref=vm-13098`          | VM managed object used as the ticket target                |
-| `snapshot_ref`                    | Not consumed by the ticket call itself                     |
-| `VIXDISKLIB_CRED_UID`             | Username/password for VIM only                             |
+| VDDK call                            | What actually happens                                      |
+| ------------------------------------ | ---------------------------------------------------------- |
+| `VixDiskLib_InitEx`                  | Load plugins, SSL, logging                                 |
+| `VixDiskLib_ConnectEx`               | SOAP `SessionManager.Login` to vCenter                     |
+| `VixDiskLib_Open` (read-only)        | `NfcGetVmFiles` ticket, then authd handshake, then NFC I/O |
+| `VixDiskLib_Open` (read-write)       | `NfcRandomAccessOpenDisk` ticket (disk key + host)         |
+| `transport_modes="nbdssl"` (default) | NBDSSL (`vpxa-nfcssl://...@esxi:902`, second TLS wrap)     |
+| `transport_modes="nbd"`              | NBD over NFC (`vpxa-nfc://...@esxi:902`)                   |
+| `vmxSpec=moref=vm-13098`             | VM managed object used as the ticket target                |
+| `snapshot_ref`                       | Not consumed by the ticket call itself                     |
+| `VIXDISKLIB_CRED_UID`                | Username/password for VIM only                             |
 
 Lab topology used for capture:
 
@@ -185,8 +186,9 @@ Plain-text connection is deprecated; use SSL to connect to NFC server
 ```
 
 `useSSL=0` does **not** mean skip TLS on 902. It means skip a second
-NFCSSL wrap after authd TLS (`THUMBPRINT_SHA2 PlainText`). The
-management channel is still TLS.
+NFCSSL wrap after authd TLS. The management channel is still TLS.
+`useSSL=1` (nbdssl) is the same authd commands with `PROXY vpxa-nfcssl`
+and a second TLS handshake after `200 Connect`.
 
 Intercepted writes/reads after the TLS handshake:
 
@@ -200,6 +202,20 @@ C -> PROXY vpxa-nfc\r\n
 S -> 200 Connect ha-nfc\r\n
 ```
 
+NBDSSL uses the same `SESSION` / `BANNER` / `THUMBPRINT_SHA2 PlainText`
+sequence. The ticket still has `service=vpxa-nfc`; the client rewrites
+the PROXY argument:
+
+```
+C -> PROXY vpxa-nfcssl\r\n
+S -> 200 Connect ha-nfcssl\r\n
+```
+
+After that reply, authd TLS is finished and `ha-nfcssl` expects a **new**
+TLS ClientHello on the same TCP connection (`useSSL=1`). NFC frames then
+travel as TLS application data of that second session. NBD (`useSSL=0`)
+skips the second wrap and sends NFC as raw TCP instead.
+
 Notes:
 
 - `SESSION` does not get a reply of its own. Waiting for a line after
@@ -209,10 +225,11 @@ Notes:
   commands, so `THUMBPRINT_SHA2 <colon-thumbprint>` is parsed as one
   token and returns `501 Invalid arguments`. `PlainText` has no extra
   spaces/colons and is the argument VDDK sends.
-- `PROXY` uses `ticket.service` (`vpxa-nfc` via vCenter). The success
-  line names the host-side NFC endpoint (`ha-nfc`).
-- After `200 Connect`, the socket speaks binary NFC (not documented
-  here).
+- `PROXY` uses `ticket.service` (`vpxa-nfc` via vCenter) for NBD. NBDSSL
+  appends `ssl` (`vpxa-nfcssl`). The success line names the host-side
+  endpoint (`ha-nfc` or `ha-nfcssl`).
+- After `200 Connect`, NBD speaks binary NFC on the raw fd. NBDSSL
+  starts a second TLS handshake, then the same NFC protocol.
 
 ### Commands that are not used for this ticket type
 
@@ -259,7 +276,8 @@ and asserts an established TLS socket on `ticket.host:ticket.port`.
 
 ## What comes after authentication
 
-Authentication stops at `200 Connect ha-nfc`. Opening the VMDK and
-reading or writing sectors is documented in `docs/nfc_open.md` and
-implemented in `openvixdisklib/nfc_open.py`. The datastore path is
-consumed there (and, for writes, as `diskDeviceKey` on the ticket).
+Authentication stops at `200 Connect ha-nfc` (NBD) or `200 Connect
+ha-nfcssl` (NBDSSL). Opening the VMDK and reading or writing sectors is
+documented in `docs/nfc_open.md` and implemented in
+`openvixdisklib/nfc_open.py`. The datastore path is consumed there
+(and, for writes, as `diskDeviceKey` on the ticket).
diff --git a/docs/nfc_open.md b/docs/nfc_open.md
index c5b9346..569cade 100644
--- a/docs/nfc_open.md
+++ b/docs/nfc_open.md
@@ -11,53 +11,60 @@ VDDK 8.0.2 verbose logs
 Authentication is already done: VIM login, NFC ticket (`NfcGetVmFiles`
 for read-only, `NfcRandomAccessOpenDisk` for write), TLS to authd,
 `SESSION` / `BANNER` / `THUMBPRINT_SHA2 PlainText` / `PROXY`. This
-stage starts at `200 Connect ha-nfc` and ends with an open file handle
-that can read and write sectors. Flags `0x1a` require the writable
-ticket; the same flags on a `GetVmFiles` ticket fail with
-`VIX_E_FILE_READ_ONLY`.
+stage starts at `200 Connect ha-nfc` (NBD) or `200 Connect ha-nfcssl`
+(NBDSSL) and ends with an open file handle that can read and write
+sectors. Flags `0x1a` require the writable ticket; the same flags on a
+`GetVmFiles` ticket fail with `VIX_E_FILE_READ_ONLY`.
 
 ## Mapping from VDDK
 
-| VDDK call / log                                      | Wire effect                                              |
-| ---------------------------------------------------- | -------------------------------------------------------- |
-| `VixDiskLib_Open`                                    | Ticket + authd (see `nfc_auth.md`), then this protocol   |
-| `NBD_ClientOpen` `vpxa-nfc://[ds] path.vmdk@esxi:902` | Datastore path is the NFC open argument, not the ticket |
-| `useSSL=0`                                           | NFC bytes are raw TCP, not `SSL_write`                   |
-| `NfcProcessSessionParams` flags `0x3`                | Classic 264-byte session messages                        |
-| `SendConnectionDataMsg` payloadInfo 4 and 7          | Client name `vddk` (4) and opId `nbdmode` (7)            |
-| Server version 11                                    | Classic version message; 11 on this ESXi 8 lab           |
-| `NfcAio_OpenSession`                                 | AIO framing after the classic handshake                  |
-| `NfcUtil_PrintFileInfoOpenFlag` `NFC_DISK` `0x1e`    | `NFC_AIO_MSG_OPEN_FILE` (read-only)                      |
-| Open without `VIXDISKLIB_FLAG_OPEN_READ_ONLY`        | `OPEN_FILE` flags `0x1a` (read-write)                    |
-| `VixDiskLib_Read` / `VixDiskLib_Write`               | `NFC_AIO_MSG_IO` + sector bytes                          |
+| VDDK call / log                                               | Wire effect                                                |
+| ------------------------------------------------------------- | ---------------------------------------------------------- |
+| `VixDiskLib_Open`                                             | Ticket + authd (see `nfc_auth.md`), then this protocol     |
+| `NBD_ClientOpen` `vpxa-nfc://[ds] path.vmdk@esxi:902`         | Datastore path is the NFC open argument, not the ticket    |
+| `NBD_ClientOpen` `vpxa-nfcssl://…` / `useSSL=1`               | Same NFC after a second TLS handshake on the authd fd      |
+| `useSSL=0`                                                    | NFC bytes are raw TCP, not `SSL_write`                     |
+| `NfcProcessSessionParams` flags `0x3`                         | Classic 264-byte session messages                          |
+| `SendConnectionDataMsg` payloadInfo 4 and 7                   | Client name `vddk` (4) and opId `nbdmode` (7)              |
+| Server version 11                                             | Classic version message; 11 on this ESXi 8 lab             |
+| `NfcAio_OpenSession`                                          | AIO framing after the classic handshake                    |
+| `NfcUtil_PrintFileInfoOpenFlag` `NFC_DISK` `0x1e`             | `NFC_AIO_MSG_OPEN_FILE` (read-only)                        |
+| Open without `VIXDISKLIB_FLAG_OPEN_READ_ONLY`                 | `OPEN_FILE` flags `0x1a` (read-write)                      |
+| `VixDiskLib_Read` / `VixDiskLib_Write`                        | `NFC_AIO_MSG_IO` + sector bytes                            |
 
 `snapshot_ref` is still not on the wire. Integration tests pass the
 flat VMDK created with the temporary lab VM.
 
-## After PROXY: plaintext on the TLS fd
+## After PROXY: NBD plaintext vs NBDSSL wrap
 
-`THUMBPRINT_SHA2 PlainText` tells authd not to wrap NFC in a second
-TLS session. VDDK logs `useSSL=0` and “Plain-text connection is
-deprecated”.
+`THUMBPRINT_SHA2 PlainText` is used for both transports. The PROXY
+service name selects whether NFC gets a second TLS session.
 
-On the wire that means:
+NBD (`PROXY vpxa-nfc` → `200 Connect ha-nfc`, VDDK `useSSL=0`):
 
 1. Authd commands stay inside the original TLS session (`SSL_write` /
    `SSL_read`).
-2. After `200 Connect ha-nfc`, VDDK calls `write(SSL_get_fd(ssl), …)`
-   and `read` on that same descriptor. Those buffers are NFC, not TLS
-   records (`0x17 0x03 …`).
-3. ESXi’s `ha-nfc` side does the same: replies are plaintext NFC.
+2. After `200 Connect ha-nfc`, NFC is `write(SSL_get_fd(ssl), …)` /
+   `read` on that descriptor. Those buffers are not TLS records
+   (`0x17 0x03 …`).
+3. An SSL hook that only interposes `SSL_write` / `SSL_read` goes
+   silent after PROXY; a `write` / `read` hook on port 902 shows the
+   frames.
+4. Python must not use `SSLSocket.send` here: that would encrypt bytes
+   the server now reads as NFC. `nfc_open.takeover_authd_socket` dups
+   the fd. `unwrap()` / `SSL_shutdown` is not used.
 
-An SSL hook that only interposes `SSL_write` / `SSL_read` therefore
-goes silent after PROXY. Interposing `write` / `read` and filtering
-`getpeername` port 902 shows the frames.
+NBDSSL (`PROXY vpxa-nfcssl` → `200 Connect ha-nfcssl`, `useSSL=1`):
 
-Python must not use `SSLSocket.send` for this stage: that would
-`SSL_write` and encrypt bytes the server now reads as NFC.
-`nfc_open.takeover_authd_socket` dups `SSL_get_fd` and uses a raw
-`socket.socket`. `unwrap()` / `SSL_shutdown` is not used; VDDK does
-not send `close_notify` before NFC.
+1. Authd commands are the same, including `THUMBPRINT_SHA2 PlainText`.
+2. After `200 Connect ha-nfcssl`, both sides abandon the authd TLS
+   session. `ha-nfcssl` expects a new ClientHello on the same TCP
+   connection.
+3. `nfc_open.wrap_nfcssl_socket` dups the fd and
+   `SSLContext.wrap_socket`s it. NFC then uses `SSLSocket.sendall` /
+   `recv` (TLS application data). The classic 264-byte handshake still
+   sends the ASCII body `PlainText`; that is NFC's own encoding, not
+   the authd transport.
 
 ## Classic 264-byte messages
 
@@ -200,6 +207,7 @@ classic type 4 `NFC_SESSION_COMPLETE`.
 | ----------------------------- | ----------------------------------------------- |
 | VIM + authd                   | `openvixdisklib.nfc_auth.authenticate`          |
 | Dup fd, skip TLS for NFC      | `openvixdisklib.nfc_open.takeover_authd_socket` |
+| Second TLS for nbdssl         | `openvixdisklib.nfc_open.wrap_nfcssl_socket`    |
 | Handshake + AIO + OPEN_FILE   | `openvixdisklib.nfc_open.open_disk`             |
 | Sector read / write / close   | `openvixdisklib.nfc_open.NfcDisk`               |
 
@@ -218,8 +226,7 @@ I/O: `docs/nfc_read.md`, `docs/nfc_write.md`, and
 
 - `DDB_GET` / geometry / compression / encryption keys
 - `NFC_DELTA_DISK`, change-block tracking
-- Host-switch (`NFC_AIO_SWITCH_HOST_*`) and a second NFCSSL wrap
-  (`useSSL=1`, not what VDDK NBD used here)
+- Host-switch (`NFC_AIO_SWITCH_HOST_*`)
 - Direct ESXi `ha-nfc` without vCenter `vpxa-nfc`
 
 Reads after open are in `docs/nfc_read.md`. Writes are in
diff --git a/docs/reverse_engineering_procedure.md b/docs/reverse_engineering_procedure.md
index 9299cb0..eddaf44 100644
--- a/docs/reverse_engineering_procedure.md
+++ b/docs/reverse_engineering_procedure.md
@@ -9,9 +9,9 @@ NFC work can follow the same loop instead of rediscovering it.
 
 Scope so far: `VixDiskLib_ConnectEx` + `VixDiskLib_Open` +
 `VixDiskLib_Read` + `VixDiskLib_Write` against lab vCenter 8.0.1 /
-ESXi 8, transport `nbd`. Driver: `tests/integration/` (the session-scoped
-`lab` fixture creates a temporary empty VM with a 10 GiB disk and
-destroys it when the pytest session ends).
+ESXi 8, transports `nbd` and `nbdssl`. Driver: `tests/integration/` (the
+session-scoped `lab` fixture creates a temporary empty VM with a 10 GiB
+disk and destroys it when the pytest session ends).
 
 Rule from `AGENTS.md`: reuse pyVmomi for every public VIM operation.
 Only reimplement what pyVmomi does not expose.
@@ -254,6 +254,32 @@ single oversized write the way VDDK sends an oversized read. Details:
 `tests/integration/test_nfc_read_write.py` and the VDDK cross-check in
 `tests/integration/test_crosscheck.py`.
 
+## Step 11 — NBDSSL: second TLS after `PROXY vpxa-nfcssl`
+
+VDDK strings name `nbdssl`, `vpxa-nfcssl://`, and `ha-nfcssl`. The NFC
+ticket SOAP call is unchanged (`service` stays `vpxa-nfc`). Transport is
+an authd/client choice:
+
+1. Same `SESSION` / `BANNER` / `THUMBPRINT_SHA2 PlainText` as NBD.
+2. `PROXY vpxa-nfcssl` → `200 Connect ha-nfcssl`.
+3. A new TLS handshake on the **same TCP connection** (not TLS-in-TLS
+   and not `THUMBPRINT_SHA2 <sha256>`). The colon thumbprint is still
+   `501 Invalid arguments`.
+4. Classic NFC handshake type 43 still sends ASCII `PlainText`. I/O
+   framing is unchanged.
+
+Replay: `connect_authd(..., nfc_ssl=True)` plus
+`nfc_open.wrap_nfcssl_socket`. Sending NFC on the first authd
+`SSLSocket` after `ha-nfcssl` fails (`BAD_RECORD_TYPE`); sending
+plaintext NFC on the dup'd fd gets EOF. Dup + `wrap_socket` is the
+working subset. Proof: `tests/integration/test_nfc_open.py` (`nbdssl`)
+and `test_openvixdisklib.py` with `transport_modes="nbdssl"`.
+
+Native `VixDiskLib_ConnectEx(..., transport_modes="nbdssl")` through
+the old `VixDiskLibConnectParams` ctypes struct can still log nbdssl
+and then fall back to `vpxa-nfc` / `useSSL=0`. Do not treat that log
+line as a wire capture of NFCSSL.
+
 ## What to write down
 
 After a stage works:
@@ -278,5 +304,4 @@ Not yet reversed, same loop as above:
 - `NFC_DELTA_DISK`, CBT / `QueryAllocatedBlocks`
 - `VixDiskLib_GetInfo` capacity
 - Host-switch AIO messages
-- `useSSL=1` (second NFCSSL wrap)
 - Direct ESXi `ha-nfc` without vCenter `vpxa-nfc`
diff --git a/openvixdisklib/nfc_auth.py b/openvixdisklib/nfc_auth.py
index c4d2bdd..96002ac 100644
--- a/openvixdisklib/nfc_auth.py
+++ b/openvixdisklib/nfc_auth.py
@@ -242,10 +242,25 @@ def _expect_code(line: str, code: str, what: str) -> str:
     return line[len(code):].lstrip()
 
 
+def nfcssl_service_name(service: str) -> str:
+    """Return the NFCSSL authd PROXY service for an NFC service name.
+
+    VCenter tickets still report ``vpxa-nfc``. NBDSSL uses
+    ``PROXY vpxa-nfcssl`` (or ``ha-nfcssl`` on a direct ESXi ticket).
+
+    Args:
+        service: Ticket ``service`` field, for example ``vpxa-nfc``.
+    """
+    if service.endswith("ssl"):
+        return service
+    return f"{service}ssl"
+
+
 def connect_authd(
         ticket: vim.HostServiceTicket,
         allow_untrusted: bool = False,
-        timeout: float = 30.0) -> ssl.SSLSocket:
+        timeout: float = 30.0,
+        nfc_ssl: bool = True) -> ssl.SSLSocket:
     """Complete the ESXi authd handshake using an NFC HostServiceTicket.
 
     Wire sequence captured from VDDK against authd on TCP 902:
@@ -253,14 +268,20 @@ def connect_authd(
     1. Read the plaintext 220 banner, then wrap the socket with TLS.
     2. SESSION <sessionId>
     3. BANNER
-    4. THUMBPRINT_SHA2 PlainText  (NFC data stays on this TLS socket)
-    5. PROXY <ticket.service>     (vpxa-nfc when connecting via vCenter)
+    4. THUMBPRINT_SHA2 PlainText
+    5. PROXY <ticket.service>     (vpxa-nfc / nbd) or vpxa-nfcssl (nbdssl)
+
+    ``THUMBPRINT_SHA2 PlainText`` is used for both transports. NBDSSL
+    is selected by the PROXY service name; after ``200 Connect
+    ha-nfcssl`` a second TLS handshake is started in ``nfc_open``.
 
     Args:
         ticket: One-time ticket from get_nfc_ticket().
         allow_untrusted: If False, require the peer SHA-1 thumbprint to match
             ticket.sslThumbprint.
         timeout: Socket timeout in seconds.
+        nfc_ssl: When True (the default), PROXY to the NFCSSL service
+            used by nbdssl. Pass False for plaintext NFC (nbd).
     """
     host = ticket.host
     port = ticket.port or AUTHD_DEFAULT_PORT
@@ -294,6 +315,8 @@ def connect_authd(
         _expect_code(_readline(ssock), "200", "THUMBPRINT_SHA2")
 
         service = ticket.service or "vpxa-nfc"
+        if nfc_ssl:
+            service = nfcssl_service_name(service)
         ssock.sendall(f"PROXY {service}\r\n".encode("ascii"))
         _expect_code(_readline(ssock), "200", "PROXY")
         return ssock
@@ -309,10 +332,12 @@ class NfcAuthSession:
             self,
             si: vim.ServiceInstance,
             ticket: vim.HostServiceTicket,
-            authd_sock: ssl.SSLSocket) -> None:
+            authd_sock: ssl.SSLSocket,
+            nfc_ssl: bool = True) -> None:
         self.si = si
         self.ticket = ticket
         self.authd_sock = authd_sock
+        self.nfc_ssl = nfc_ssl
 
     def close(self) -> None:
         """Close the authd socket and logout of the VIM session."""
@@ -338,7 +363,8 @@ def authenticate(
         allow_untrusted: bool = False,
         disk_device_key: Optional[int] = None,
         disk_path: Optional[str] = None,
-        read_only: bool = True) -> NfcAuthSession:
+        read_only: bool = True,
+        nfc_ssl: bool = True) -> NfcAuthSession:
     """Login to vSphere and complete NFC authd authentication for a VM.
 
     Args:
@@ -354,6 +380,8 @@ def authenticate(
         disk_path: Datastore path used to resolve ``disk_device_key``.
         read_only: When False, request a writable ``NfcRandomAccessOpenDisk``
             ticket.
+        nfc_ssl: When True (the default), complete authd with the NFCSSL
+            PROXY service used by nbdssl. Pass False for nbd.
     """
     si = connect_vim(
         host, username, password, port=port,
@@ -364,8 +392,8 @@ def authenticate(
             si, vm, disk_device_key=disk_device_key,
             disk_path=disk_path, read_only=read_only)
         authd_sock = connect_authd(
-            ticket, allow_untrusted=allow_untrusted)
+            ticket, allow_untrusted=allow_untrusted, nfc_ssl=nfc_ssl)
     except Exception:
         Disconnect(si)
         raise
-    return NfcAuthSession(si, ticket, authd_sock)
+    return NfcAuthSession(si, ticket, authd_sock, nfc_ssl=nfc_ssl)
diff --git a/openvixdisklib/nfc_open.py b/openvixdisklib/nfc_open.py
index 7b7f0e1..0f9f389 100644
--- a/openvixdisklib/nfc_open.py
+++ b/openvixdisklib/nfc_open.py
@@ -3,10 +3,12 @@
 
 """VDDK-compatible NFC disk open, sector read, and sector write.
 
-After ``nfc_auth.connect_authd`` returns ``200 Connect``, VDDK stops using
-``SSL_write`` on the authd socket. ``THUMBPRINT_SHA2 PlainText`` means the
-NFC binary protocol runs as raw TCP on that same file descriptor
-(``useSSL=0``). This module dups that fd and speaks:
+After ``nfc_auth.connect_authd`` returns ``200 Connect``, NBD
+(``useSSL=0``) stops using ``SSL_write`` and speaks NFC as raw TCP on
+that file descriptor. NBDSSL (``useSSL=1``) starts a second TLS
+handshake on the same TCP connection (``200 Connect ha-nfcssl``) and
+speaks the same NFC frames as TLS application data. This module dups
+the authd fd and speaks:
 
 1. Classic 264-byte NFC messages (handshake, version, connection data,
    AIO session open).
@@ -24,7 +26,7 @@ import socket
 import ssl
 import struct
 
-from openvixdisklib.nfc_auth import NfcAuthSession
+from openvixdisklib.nfc_auth import NfcAuthSession, _ssl_client_context
 
 NFC_MSG_SIZE = 264
 NFC_AIO_MAGIC = 0xA100DA7A
@@ -93,6 +95,30 @@ def takeover_authd_socket(ssock: ssl.SSLSocket) -> socket.socket:
     return raw
 
 
+def wrap_nfcssl_socket(
+        ssock: ssl.SSLSocket,
+        server_hostname: str) -> ssl.SSLSocket:
+    """Start the second TLS session used by NBDSSL after PROXY.
+
+    After ``200 Connect ha-nfcssl``, authd TLS is finished and
+    ``ha-nfcssl`` expects a new ClientHello on the same TCP connection.
+    The fd is dup'd so the original authd ``SSLSocket`` can be closed
+    later without ``SSL_shutdown`` of this NFCSSL session.
+
+    Args:
+        ssock: The TLS socket from ``nfc_auth.connect_authd``.
+        server_hostname: Host name passed to ``SSLContext.wrap_socket``.
+    """
+    raw = takeover_authd_socket(ssock)
+    ssl_context = _ssl_client_context(verify=False)
+    try:
+        return ssl_context.wrap_socket(
+            raw, server_hostname=server_hostname)
+    except Exception:
+        raw.close()
+        raise
+
+
 def _recvn(sock: socket.socket, size: int) -> bytes:
     buf = bytearray()
     while len(buf) < size:
@@ -146,7 +172,7 @@ class NfcDisk:
         """Wrap an AIO session that already has ``path`` open.
 
         Args:
-            sock: Raw NFC socket after handshake.
+            sock: NFC socket after handshake (raw TCP for nbd, TLS for nbdssl).
             path: Datastore path that was opened.
             handle: Server file handle from OPEN_FILE.
             sector_size: Sector size from the OPEN_FILE reply.
@@ -401,7 +427,9 @@ def open_disk(
 
     Matches VDDK ``VixDiskLib_Open`` of a datastore path after the NFC
     ticket and authd PROXY handshake: session init, AIO open, then
-    ``NFC_AIO_MSG_OPEN_FILE`` with type ``NFC_DISK``.
+    ``NFC_AIO_MSG_OPEN_FILE`` with type ``NFC_DISK``. NBD dups the
+    authd fd and sends plaintext NFC. NBDSSL wraps that dup in a
+    second TLS session (``session.nfc_ssl``).
 
     Args:
         session: Result of ``nfc_auth.authenticate``.
@@ -412,7 +440,11 @@ def open_disk(
         version: Client NFC protocol version (lab ESXi answered 11).
         read_only: When True, open with VDDK's read-only NFC flags.
     """
-    sock = takeover_authd_socket(session.authd_sock)
+    if session.nfc_ssl:
+        sock = wrap_nfcssl_socket(
+            session.authd_sock, session.ticket.host)
+    else:
+        sock = takeover_authd_socket(session.authd_sock)
     try:
         _handshake(sock, client_name, op_id, version)
         disk = NfcDisk(sock, disk_path, handle=0, sector_size=NFC_SECTOR_SIZE)
diff --git a/openvixdisklib/openvixdisklib.py b/openvixdisklib/openvixdisklib.py
index 2963001..759ab29 100644
--- a/openvixdisklib/openvixdisklib.py
+++ b/openvixdisklib/openvixdisklib.py
@@ -70,13 +70,20 @@ def _parse_vm_moref(vmx_spec: Optional[str]) -> str:
     return vmx_spec
 
 
-def _require_nbd(transport_modes: Optional[str]) -> None:
+def _select_transport(transport_modes: Optional[str]) -> str:
+    """Return the first requested transport this replacement implements.
+
+    ``None`` defaults to ``nbdssl``. A colon-separated list (VDDK
+    style, for example ``file:nbdssl:nbd``) picks the first of
+    ``nbdssl`` or ``nbd``.
+    """
     if transport_modes is None:
-        return
-    modes = [m for m in transport_modes.split(":") if m]
-    if "nbd" not in modes:
-        raise NotImplementedError(
-            f"only nbd transport is supported, got {transport_modes!r}")
+        return "nbdssl"
+    for mode in transport_modes.split(":"):
+        if mode in ("nbdssl", "nbd"):
+            return mode
+    raise NotImplementedError(
+        f"supported transports are nbdssl and nbd, got {transport_modes!r}")
 
 
 class _Connection:
@@ -89,13 +96,15 @@ class _Connection:
             snapshot_ref: Optional[str],
             thumbprint: Optional[str],
             allow_untrusted: bool,
-            read_only: bool) -> None:
+            read_only: bool,
+            transport_mode: str) -> None:
         self.si = si
         self.vm_moref = vm_moref
         self.snapshot_ref = snapshot_ref
         self.thumbprint = thumbprint
         self.allow_untrusted = allow_untrusted
         self.read_only = read_only
+        self.transport_mode = transport_mode
 
 
 class _DiskHandle:
@@ -104,9 +113,11 @@ class _DiskHandle:
     def __init__(
             self,
             disk: nfc_open.NfcDisk,
-            authd_sock) -> None:
+            authd_sock,
+            transport_mode: str) -> None:
         self.disk = disk
         self.authd_sock = authd_sock
+        self.transport_mode = transport_mode
 
 
 class VixDiskLibHandle:
@@ -161,12 +172,11 @@ class VixDiskLibHandle:
 
     def get_transport_modes(self) -> list[str]:
         """Return the transport modes this replacement implements."""
-        return ["nbd"]
+        return ["nbdssl", "nbd"]
 
     def get_transport_mode(self, disk_handle: _DiskHandle) -> str:
         """Return the transport used for ``disk_handle``."""
-        del disk_handle
-        return "nbd"
+        return disk_handle.transport_mode
 
     @contextlib.contextmanager
     def connect(
@@ -196,12 +206,14 @@ class VixDiskLibHandle:
             vmx_spec: VM selector, ``moref=vm-…``.
             snapshot_ref: Snapshot moref; unused on the NFC ticket.
             read_only: When False, the disk may be opened for write.
-            transport_modes: ``nbd`` or a colon list that includes ``nbd``.
+            transport_modes: ``nbdssl``, ``nbd``, or a colon list. The
+                first supported mode is used; ``None`` defaults to
+                ``nbdssl``.
             port: HTTPS port, usually 443.
             allow_untrusted: Skip management TLS verification when True.
         """
         LOG.debug("Connecting VixDiskLib: %s", server_name)
-        _require_nbd(transport_modes)
+        transport_mode = _select_transport(transport_modes)
         vm_moref = _parse_vm_moref(vmx_spec)
         si = nfc_auth.connect_vim(
             server_name,
@@ -212,7 +224,8 @@ class VixDiskLibHandle:
             allow_untrusted=allow_untrusted or not thumbprint)
         conn = _Connection(
             si, vm_moref, snapshot_ref, thumbprint,
-            allow_untrusted or not thumbprint, read_only)
+            allow_untrusted or not thumbprint, read_only,
+            transport_mode)
         try:
             yield conn
         finally:
@@ -243,18 +256,20 @@ class VixDiskLibHandle:
                 "ConnectEx was read-only; cannot open for write")
 
         vm = vim.VirtualMachine(conn.vm_moref, conn.si._stub)
+        nfc_ssl = conn.transport_mode == "nbdssl"
         ticket = nfc_auth.get_nfc_ticket(
             conn.si, vm, read_only=read_only, disk_path=disk_path)
         authd_sock = nfc_auth.connect_authd(
-            ticket, allow_untrusted=conn.allow_untrusted)
-        session = nfc_auth.NfcAuthSession(conn.si, ticket, authd_sock)
+            ticket, allow_untrusted=conn.allow_untrusted, nfc_ssl=nfc_ssl)
+        session = nfc_auth.NfcAuthSession(
+            conn.si, ticket, authd_sock, nfc_ssl=nfc_ssl)
         try:
             disk = nfc_open.open_disk(
                 session, disk_path, read_only=read_only)
         except Exception:
             authd_sock.close()
             raise
-        handle = _DiskHandle(disk, authd_sock)
+        handle = _DiskHandle(disk, authd_sock, conn.transport_mode)
         try:
             yield handle
         finally:
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..65a9866
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,37 @@
+# Copyright 2026 Cloudbase Solutions Srl
+# All Rights Reserved.
+
+"""Session-scoped lab fixtures for live vSphere tests."""
+
+from __future__ import annotations
+
+import os
+from collections.abc import Iterator
+
+import pytest
+
+from tests.integration.base import (
+    LabEnv,
+    create_lab_vm,
+    destroy_lab_vm,
+    ensure_vddk_library_path,
+    require_vddk,
+)
+
+
+@pytest.fixture(scope="session")
+def lab() -> Iterator[LabEnv]:
+    """Create one temporary lab VM for the whole pytest session."""
+    os.environ.pop("LD_PRELOAD", None)
+    ensure_vddk_library_path()
+    env = create_lab_vm()
+    try:
+        yield env
+    finally:
+        destroy_lab_vm(env)
+
+
+@pytest.fixture(scope="session")
+def vddk() -> None:
+    """Skip VDDK-backed tests when ``libvixDiskLib`` cannot be loaded."""
+    require_vddk()
diff --git a/tests/integration/base.py b/tests/integration/base.py
index 39f21a5..133ca5c 100644
--- a/tests/integration/base.py
+++ b/tests/integration/base.py
@@ -60,7 +60,10 @@ class LabEnv:
     vmx_spec: str
     disk_path: str
 
-    def authenticate(self, read_only: bool = True) -> NfcAuthSession:
+    def authenticate(
+            self,
+            read_only: bool = True,
+            nfc_ssl: bool = True) -> NfcAuthSession:
         """Login to the lab vCenter and complete NFC authd for the temp VM."""
         return nfc_auth.authenticate(
             host=self.host,
@@ -70,7 +73,8 @@ class LabEnv:
             thumbprint=self.thumbprint,
             allow_untrusted=self.allow_untrusted,
             disk_path=None if read_only else self.disk_path,
-            read_only=read_only)
+            read_only=read_only,
+            nfc_ssl=nfc_ssl)
 
     def vixdisklib_connect_kwargs(
             self, extra: Optional[dict[str, Any]] = None) -> dict[str, Any]:
@@ -82,7 +86,7 @@ class LabEnv:
             "username": self.username,
             "password": self.password,
             "vmx_spec": self.vmx_spec,
-            "transport_modes": "nbd",
+            "transport_modes": "nbdssl",
             "read_only": False,
         }
         if extra:
diff --git a/tests/integration/test_nfc_auth.py b/tests/integration/test_nfc_auth.py
index 5d46e09..e074f1e 100644
--- a/tests/integration/test_nfc_auth.py
+++ b/tests/integration/test_nfc_auth.py
@@ -14,5 +14,14 @@ class TestNfcAuth:
             assert ticket.host
             assert ticket.port
             assert ticket.sessionId
+            assert session.nfc_ssl is True
+            assert session.authd_sock.version()
+            assert session.authd_sock.cipher()
+
+    def test_authd_nbd_handshake_completes(self, lab: LabEnv) -> None:
+        """Complete authd with plaintext NFC after PROXY (nbd)."""
+        with lab.authenticate(nfc_ssl=False) as session:
+            assert session.nfc_ssl is False
+            assert session.ticket.sessionId
             assert session.authd_sock.version()
             assert session.authd_sock.cipher()
diff --git a/tests/integration/test_nfc_open.py b/tests/integration/test_nfc_open.py
index 874c0cc..20d6c34 100644
--- a/tests/integration/test_nfc_open.py
+++ b/tests/integration/test_nfc_open.py
@@ -3,15 +3,20 @@
 
 """Exercise NFC disk open and a one-sector write/read against the lab."""
 
+import pytest
+
 from openvixdisklib import nfc_open
 from tests.integration.base import LabEnv, SECTOR_SIZE, pattern_bytes
 
 
 class TestNfcOpen:
-    def test_open_disk_and_read_first_sector(self, lab: LabEnv) -> None:
+    @pytest.mark.parametrize(
+        "nfc_ssl", [True, False], ids=["nbdssl", "nbd"])
+    def test_open_disk_and_read_first_sector(
+            self, lab: LabEnv, nfc_ssl: bool) -> None:
         """Open the temp VMDK, write sector 0, and read it back."""
         expected = pattern_bytes(SECTOR_SIZE, b"NFC-OPEN-S0")
-        with lab.authenticate(read_only=False) as session:
+        with lab.authenticate(read_only=False, nfc_ssl=nfc_ssl) as session:
             with nfc_open.open_disk(
                     session, lab.disk_path, read_only=False) as disk:
                 assert disk.path == lab.disk_path
diff --git a/tests/integration/test_openvixdisklib.py b/tests/integration/test_openvixdisklib.py
index 9831001..c006b35 100644
--- a/tests/integration/test_openvixdisklib.py
+++ b/tests/integration/test_openvixdisklib.py
@@ -3,13 +3,17 @@
 
 """Exercise the VDDK-compatible openvixdisklib handle against the lab."""
 
+import pytest
+
 from openvixdisklib import openvixdisklib as vixdisklib
 from tests.integration.base import (
     LabEnv, SECTOR_AT_1GB, SECTOR_SIZE, pattern_bytes)
 
 
 class TestOpenvixdisklib:
-    def test_write_and_read_sector_zero_and_one_gib(self, lab: LabEnv) -> None:
+    @pytest.mark.parametrize("transport_mode", ["nbdssl", "nbd"])
+    def test_write_and_read_sector_zero_and_one_gib(
+            self, lab: LabEnv, transport_mode: str) -> None:
         """Write then read sector 0 and the sector at a 1 GiB offset."""
         handle = vixdisklib.VixDiskLibHandle(
             vixdisklib_compatibility_version="8.0",
@@ -18,13 +22,16 @@ class TestOpenvixdisklib:
         read_buf = vixdisklib.get_buffer(SECTOR_SIZE)
         connect_kwargs = lab.vixdisklib_connect_kwargs({
             "allow_untrusted": lab.allow_untrusted,
+            "transport_modes": transport_mode,
         })
         patterns = {
             0: pattern_bytes(SECTOR_SIZE, b"OVDL-S0"),
             SECTOR_AT_1GB: pattern_bytes(SECTOR_SIZE, b"OVDL-1GB"),
         }
+        assert handle.get_transport_modes() == ["nbdssl", "nbd"]
         with handle.connect(**connect_kwargs) as conn:
             with handle.open(conn, lab.disk_path, flags=0) as disk:
+                assert handle.get_transport_mode(disk) == transport_mode
                 for start, expected in patterns.items():
                     write_buf[:SECTOR_SIZE] = expected
                     handle.write(disk, start, 1, write_buf)
diff --git a/tests/perf/__init__.py b/tests/perf/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/perf/test_compare.py b/tests/perf/test_compare.py
new file mode 100644
index 0000000..2a2ab8c
--- /dev/null
+++ b/tests/perf/test_compare.py
@@ -0,0 +1,88 @@
+# Copyright 2026 Cloudbase Solutions Srl
+# All Rights Reserved.
+
+"""Compare openvixdisklib and native VDDK I/O throughput against the lab."""
+
+from __future__ import annotations
+
+import time
+from typing import Any, Optional
+
+from openvixdisklib import openvixdisklib as open_vix
+from tests.integration import vixdisklib
+from tests.integration.base import LabEnv, SECTOR_SIZE, pattern_bytes
+
+_SIZES = (
+    ("64KiB", 64 * 1024),
+    ("129 sectors", 129 * SECTOR_SIZE),
+    ("32MiB", 32 * 1024 * 1024),
+)
+
+
+def _connect_extra(lab: LabEnv, module: Any) -> Optional[dict[str, Any]]:
+    """Return extra ``connect`` kwargs needed by ``module``."""
+    if module is open_vix:
+        return {"allow_untrusted": lab.allow_untrusted}
+    return None
+
+
+def _time_write_read(
+        lab: LabEnv,
+        module: Any,
+        payload: bytes) -> tuple[float, float]:
+    """Write ``payload`` at sector 0, read it back, and return durations."""
+    n_sectors = len(payload) // SECTOR_SIZE
+    handle = module.VixDiskLibHandle(
+        vixdisklib_compatibility_version="8.0",
+        config_path=None)
+    write_buf = module.get_buffer(len(payload))
+    read_buf = module.get_buffer(len(payload))
+    write_buf[:len(payload)] = payload
+    kwargs = lab.vixdisklib_connect_kwargs(_connect_extra(lab, module))
+    with handle.connect(**kwargs) as conn:
+        with handle.open(conn, lab.disk_path, flags=0) as disk:
+            started = time.perf_counter()
+            handle.write(disk, 0, n_sectors, write_buf)
+            write_s = time.perf_counter() - started
+            read_buf[:len(payload)] = b"\xa5" * len(payload)
+            started = time.perf_counter()
+            handle.read(disk, 0, n_sectors, read_buf)
+            read_s = time.perf_counter() - started
+    assert read_buf.raw[:len(payload)] == payload
+    return write_s, read_s
+
+
+def _mib_per_s(nbytes: int, seconds: float) -> float:
+    if seconds <= 0:
+        return float("inf")
+    return (nbytes / (1024 * 1024)) / seconds
+
+
+class TestCompare:
+    def test_write_read_throughput(self, lab: LabEnv, vddk: None) -> None:
+        """Time matching write/read sizes on VDDK and openvixdisklib."""
+        libraries = (
+            ("vddk", vixdisklib),
+            ("openvixdisklib", open_vix),
+        )
+        rows: list[tuple[str, str, float, float, float, float]] = []
+        for label, nbytes in _SIZES:
+            payload = pattern_bytes(nbytes, f"PERF-{label}-".encode())
+            for name, module in libraries:
+                write_s, read_s = _time_write_read(lab, module, payload)
+                rows.append((
+                    label,
+                    name,
+                    write_s,
+                    read_s,
+                    _mib_per_s(nbytes, write_s),
+                    _mib_per_s(nbytes, read_s),
+                ))
+        print()
+        print(
+            f"{'size':<14} {'library':<16} {'write_s':>10} {'read_s':>10} "
+            f"{'write_MiB/s':>12} {'read_MiB/s':>12}")
+        for label, name, write_s, read_s, write_r, read_r in rows:
+            print(
+                f"{label:<14} {name:<16} {write_s:10.3f} {read_s:10.3f} "
+                f"{write_r:12.1f} {read_r:12.1f}")