ncrp

Project primer

ncrp — NCRP relay / rendezvous server (review primer)

An internet-facing Qt/C++ rendezvous + relay server for NinjaRemote: peers connect,
it authenticates and pairs the two sides of a session, then relays their encrypted PeerData
byte-for-byte (it does NOT decrypt session payload). Also handles a UDP NAT-traversal path.

Architecture (durable map)

• An acceptor distributes incoming TCP connections across a pool of worker threads

(sharded thread-per-worker).

• Each connection is a state-machine object running the NCRP handshake; when two peers share a

session they are paired and the server relays packets between them.

• Session/peer state is reference-counted; a UDP DUT path handles NAT traversal.
• A shared common/ directory is shared with ncpeer clients — transport framing, DUT, and

the digest/auth algorithm live there and are cross-repo.

What matters most when reviewing here (durable risk areas)

• The Connect handshake is the security gate. Untrusted bytes from the internet are parsed

BEFORE session authentication; the digest/token check is all that stands between an anonymous
connection and session association. This is the highest-scrutiny code.

• Peer-pairing lifetime / disconnect races. The cross-peer back-pointer is a raw pointer

while session state is ref-counted — a disconnect race is a real use-after-free risk. Any
change to pairing/teardown needs careful lifetime reasoning.

• Internet-facing robustness. Connection/session handling, fd/socket lifetime, and resource

exhaustion under load/abuse — no unbounded growth; clean teardown on every error path.

• The UDP DUT path is internet-exposed with only token validation + blacklisting — scrutinize.
• Protocol packet-type cap. The packet-type set is capped (for stream-sync recovery) — that

constraint must survive protocol changes.

Security-sensitive zones

The pre-auth handshake parser + session digest/token verification; the DUT UDP path; the relay
pairing logic (mixing up peers = cross-session data leak).

Compatibility surfaces (contracts that must not silently break)

• The NCRP wire protocol + digest/auth algorithm + DUT format — **shared with ncpeer via

common/**; client and server run at different versions, so changes must stay compatible.

• The packet-type enum / cap.

Conventions & gotchas

• The server relays session payload without decrypting it — confidentiality lives in the peers;

never add logging that dumps relayed content.

• common/ is shared with the client — a change there affects ncpeer too.

_Orientation only — verify current specifics in the code; this describes durable architecture &
risk areas, not a snapshot._

Ecosystem map

NinjaRemote / NinjaOne project ecosystem (relationship map)

How the monitored repos relate — so a change in one repo is reviewed with its blast
radius in mind (a change upstream of ncpeer can break ncpeer even if it looks local).
Orientation only; verify specifics in code.

NinjaRemote product

• ncpeer — the remote-desktop client/agent (streamer host + player viewer). The hub.
• ncrp — the server/relay component NinjaRemote peers connect through; ncpeer ⇄ ncrp

speak the NCRP wire protocol (protocol/format changes must stay compatible across
client and server versions).

• ncinstaller — installs the ncpeer player onto end machines.
• qclauncher — bootstraps/launches an ncpeer quick-connect session.

Cloud-side relays of the ninja-remote system (AWS-hosted, Python/Go)

• websocket-switch — generic WebSocket pairing relay: two clients join with signed

URLs, it pairs them and forwards frames verbatim. Signed join URLs are minted by the
Ninja backend — the signature scheme is a backend⇄relay contract, and the frame
semantics are a peer⇄peer contract.

• file-transfer-service — the same pairing idea over plain HTTP for file transfer:

a signed upload leg streams to a signed download leg through memory (never stored).
Two parallel implementations (Python ftsv2/ + Go fts_go/) must stay behaviorally
identical; the URL/signature scheme is shared-family with websocket-switch.
NinjaRemote file-transfer features ride on these relays when peers can't go direct.

Pulled INTO ncpeer (and sometimes nmsnj) — upstream of the products

• nccommon — shared C++ library; a submodule of BOTH ncpeer and nmsnj. An API/ABI

or behaviour change here affects both consumers.

• nr-i18n — localization resources; a submodule of ncpeer.
• nrvirtdisplay — Windows virtual-display driver used by ncpeer.
• nrvusb — virtual-USB driver used by ncpeer.
• ncpeer_vcpkg — the pinned/patched dependency set (vcpkg fork) that **ncpeer and nmsnj

build against**. A dependency bump changes what those products link (security/ABI/build).

• ncpeer_qt6win7 — patched Qt6 (QtBase) for legacy-OS support, delivered to the clients

through the ncpeer_vcpkg overlay.

Largely independent

• nmsnj — network-management delegate (talks to the Ninja Backend over WAMP/RPC);

shares nccommon and ncpeer_vcpkg with ncpeer.

• ninjaflow — packet-capture library + agent (a distinct network-telemetry product, NOT

part of the remote-desktop family). Runs as a child process of the NinjaRMM agent (the
parent owns install/upgrade/policy/launch); NinjaFlow owns the CLI contract, config schema,
credential precedence, DB schema/migrations, and exit-code meanings the parent consumes —
those are cross-process contracts. Submits telemetry to the Ninja Backend. Shares no code with
ncpeer/nmsnj; adjacent to nmsnj only in domain (network), not in implementation.

• desktop-companion — internal companion app; mostly standalone.
• spaceship — AppSec SBOM-ingestion backend (Python/Flask). A distinct security product,

not part of any product's build. It consumes the SBOMs the other products' pipelines emit
(Ninja-Remote/ncpeer, NMS/nmsnj, NinjaFlow all appear in its scope maps), scans them for CVEs
and files Jira issues — a downstream *security-scanning* relationship, not a code dependency.
Shares no code with the others; has its own DB/schema and a toolbox submodule.

• ssh-pam-ninja — SSH one-time-password PAM gatekeeper (Linux C). A standalone

authentication component: its pam_ninja.so gates SSH reverse-tunnel access into
Ninja infrastructure with a time-based OTP. Shares no code with the other repos; its
blast radius is operational (who can SSH-tunnel into hosts), not code-level. The client OTP
generators and the module must agree on the OTP scheme + shared secret.

Review implications

• Reviewing nccommon / nr-i18n / nrvirtdisplay / nrvusb / ncpeer_vcpkg / ncpeer_qt6win7:

these are *upstream* of ncpeer (and nccommon/vcpkg also of nmsnj) — weigh the consumer
side: API/ABI compatibility, build impact, and cross-platform reach.

• Reviewing ncpeer or ncrp: the NCRP wire protocol between them is a cross-version

contract.