Two opt-in (default off) features directly targeting the kind of operator
dragnet described in the news context — make the server harder to identify
on a scan, and the traffic harder to fingerprint by volume/timing analysis.
1) Port-knocking (probe resistance, UDP)
- Wire: every HS datagram (0x01) is prefixed with a 16-byte HMAC token
when UdpOpts.knock_required is on:
knock = HMAC-SHA256(knock_key, u64_be(unix_minute))[..16]
- Server-side: validates against {now-1, now, now+1} minutes (3-minute
window for clock skew, constant-time compare). Invalid -> silent drop;
the port looks closed to scanners.
- knock_key comes from the CLI (derived from CA fingerprint at the
deployment layer); transport just consumes it.
- DATA datagrams unchanged (AEAD already proves legitimacy past hs).
2) Cover traffic (chaff, UDP)
- Optional background task per UdpConnection: every random delay
(mean_interval_ms +/- jitter, default 500ms +/- 50%) sends a
Frame::Ping{seq=random} when no Data was sent in the recent window
(idle-skip => zero overhead under load). RAII-aborted on Drop.
- Receiver answers Ping with Pong (existing logic); both are consumed
internally by recv_packet, invisible to the app.
API: UdpOpts gains knock_required/knock_key/cover_traffic_enabled/
cover_mean_interval_ms/cover_jitter (all defaults preserve v2 behavior).
Helpers exported: knock_for_minute, KNOCK_LEN.
Local deps: hmac 0.12 + sha2 0.10 (already in workspace lockfile, no new
resolution). Workspace: 185 tests passed (+11), clippy -D warnings clean,
fmt clean. 174 baseline tests unchanged.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
DIRECT-destination traffic now bypasses the TUN entirely via OS routing
table edits, instead of going through user-space and hitting the v1
send_direct stub. The user-space router only sees VPN-bound packets,
making the split-tunnel real.
- aura_cli::os_routes::OsRouteGuard: RAII install + rollback of OS routes.
Linux: `ip route show default` parser -> DIRECT CIDRs via original gw,
VPN default via TUN with metric 50. macOS: `route -n get default`
parser -> `route add -net/-host ... <gw>` for DIRECT, `route add -net
... -interface <tun>` for VPN. Windows: stub + warning (v3).
- dry_run works on every platform (logs `would run: ...`); useful for
tests and operator confidence-checks.
- SplitRoutes::from_config folds [[tunnel.split.direct]]/[[...vpn]] +
resolved domains (via AuraDns) into one declarative plan.
- New [tunnel.os_routes] {enabled (default true), dry_run, gateway,
egress_iface}; absent section = old user-space behavior (back-compat).
- client::run installs routes after AuraTun::create, before privdrop;
guard's Drop reverts everything on shutdown.
- aura-tunnel::router unchanged; AuraRouter::send_direct kept as a
defensive fallback (in v2 it should never fire — OS routes prevent
DIRECT packets from reaching the TUN at all).
20 new tests (linux/macos parser unit tests, install dry-run, config
back-compat). Workspace: 174 tests passed (+19), clippy -D warnings
clean, fmt clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Three v2-hardening features in aura-cli, one pass:
- nat::NatGuard: RAII auto-config of IP forwarding + MASQUERADE on server
startup. Linux (sysctl ip_forward + iptables -t nat MASQUERADE) and
macOS (sysctl ip.forwarding + pfctl with /tmp/aura-nat.conf). dry_run
works on every platform (logs "would run: ..."). Reverts everything in
Drop. New [server.nat] {auto, egress_iface, dry_run}; absent section =
back-compat no-op. Removes v1's "manual NAT/forwarding" step.
- privdrop::drop_to_user: drop euid/gid after binding TUN + privileged
ports. Linux setresuid/setresgid, macOS setgid+setuid (permanent drop),
Windows no-op with warning. New [server] / [client] run_as = "..."
(optional). Skipped with info-log if already non-root.
- admin: split transport into cfg(unix) Unix-socket and cfg(windows) Tokio
named-pipe modules sharing one JSON-line serve/request flow over
AsyncRead/AsyncWrite. DEFAULT_SOCKET = "/tmp/aura-admin.sock" on Unix,
r"\\.\pipe\aura-admin" on Windows. Removes v1's "admin Unix-only".
Deps: nix 0.29 user feature under [target.'cfg(unix)'.dependencies] (cli-
local, not workspace). Workspace: 155 tests passed (+13), clippy -D warnings
clean, fmt clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
The TCP fallback now does a full outer TLS handshake (tokio-rustls 0.26 over
rustls 0.23, ring provider) before the Aura proto handshake, exactly like the
QUIC backend: on the wire it is indistinguishable from genuine HTTPS until the
inner Aura mutual-auth handshake starts. Removes v1's "light HTTP masquerade"
limitation; the real security boundary remains the inner PQ handshake.
- aura-transport::tcp: dropped the HTTP/1.1 preamble helpers and TcpOpts
fields (masquerade, host, user_agent, server_header). New flow:
TlsAcceptor::accept (server) / TlsConnector::connect (client) →
tokio::io::split(TlsStream) → server_handshake / client_handshake → Session.
Client reuses crate::quic::AcceptAnyServerCert (outer SNI not authenticated;
inner handshake is the security boundary). Outer server cert auto-sourced
from proto_cfg.server_cert_pem (no API change for the CLI's bind).
- ALPN default: ["h2", "http/1.1"] (DEFAULT_TCP_ALPN, exported).
- TcpOpts: now just { alpn: Option<Vec<Vec<u8>>> }.
- TcpClient::connect gains an outer-SNI &str param; DialConfig.sni passes it
through (separate from the inner proto_cfg.server_name).
- tokio-rustls 0.26 added as a transport-local dependency (not workspace).
CLI updates: removed dead host/user_agent/server_header wiring; mask rotation
no longer touches TCP outer parameters (TLS doesn't have a Host header on
the wire). [transport] masquerade kept as a no-op for back-compat with old
configs (documented).
3 new tcp_loopback tests (default ALPN end-to-end, custom ALPN, outer SNI
mismatch still connects = proves accept-any is in effect). Workspace: 142
tests passed (+1), clippy -D warnings clean, fmt clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Server now assigns each connected client an IP from a configurable pool and
maintains a client_ip -> AuraConnection map so packets read from the shared
TUN are dispatched to the right client (and each client's recv loop writes
back to the TUN). Removes v1's "single shared TUN, no NAT/pool" limitation;
turns the server into a proper multi-client VPN concentrator (paired with the
already-landed UDP multi-client demux).
- aura_cli::pool: IpPool + PoolStrategy {StaticOnly, DynamicOnly,
StaticOrDynamic}; reserves network/broadcast/server-own IP; 15 tests.
- aura_cli::server_router: ServerRouter + ServerRoutes (Arc<RwLock<HashMap>>);
central TUN read loop dispatching by dst_ip; spawn_inbound_forwarder per
conn auto-unregisters and releases the IP on disconnect; 4 tests via
MockTun + MockConn.
- aura_cli::config: [server.pool] {cidr, strategy, static} added with
serde(default); legacy configs (only [tunnel] pool_cidr) fall back to a
DynamicOnly pool (backward compatible, tested).
- aura_cli::server: accept loop now: pool.assign(peer_id) -> register ->
spawn_inbound_forwarder; rejected static_only mismatches dropped+logged.
- config/server.toml.example: documented [server.pool] section.
Workspace: 141 tests passed (+24), clippy -D warnings clean, fmt clean. No
new workspace deps (async-trait added to cli dev-deps for mock traits in tests).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
UdpServer now serves many concurrent peers on one socket (removes v1's
"one peer per accept" limitation). PeerSocket becomes an enum:
ConnectedClient (client side, unchanged behavior) vs SharedServer (server
side, channel-fed inbox). A master loop reads the shared socket and
routes datagrams to the right per-peer inbox by source address; an
unknown peer's first TYPE_HS datagram spawns a new handshake task that,
on success, hands the established UdpConnection to accept(). Cleanup is
lazy via mpsc::Closed — handshake failures and connection drops self-
evict from the map. A small Arc<MasterTask> keeps the loop alive for the
lifetime of UdpServer OR any spawned UdpConnection, so existing single-
client tests (which move UdpServer into an accept task) still pass.
ReliableHsAdapter and run_reliable_handshake are unchanged. UdpClient
API unchanged. Added 3 tests: two concurrent clients with cross-talk
isolation, bad-CA client doesn't block legitimate ones, dropped peer
doesn't block others. Workspace: 117 tests green, clippy/fmt clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Both server and client deterministically rotate the on-wire obfuscation mask
(SNI, HTTP Host/User-Agent/Server headers, UDP padding profile) at 05:00 Moscow
time (02:00 UTC) every day, derived from the CA fingerprint + UTC date — no
network coordination needed.
- aura-crypto::masks: MaskSet + 4 palettes (16 SNI, 10 UA, 5 Server, 4 padding
profiles); derive_mask_for_msk_date via HKDF-SHA256(salt="aura-mask-v1-salt",
ikm=ca_fp||"YYYY-MM-DD", info="aura-mask-v1"); ca_fingerprint with built-in
base64 PEM decode (no new deps).
- aura-cli::masks: MaskRotator (Arc<RwLock<MaskSet>>) + Hinnant's civil_from_days
for manual UTC date math; scheduler picks next 02:00 UTC strictly (avoids
busy-loop at boundary); spawned at startup in server::run/client::run.
- aura-transport: PADDING_PROFILES + next_bucket_for_profile (profile 0 byte-for-
byte equals legacy pad_to_https_size); TcpOpts gains user_agent/server_header;
UdpOpts gains padding_profile; MultiServer holds Arc<UdpServer>/Arc<TcpServer>
with set_udp_opts/set_tcp_opts so rotation propagates without restart.
- Backward-compatible: defaults preserve previous behavior; existing 97 tests
unchanged. 17 new tests (derive determinism + date variation, civil-from-days
known points incl. 1970-01-01/2000-02-29/2024->2025, next-rotation boundary,
msk_today offset, profile equivalence, base64 round-trip, full mask-driven
UDP loopback). Total: 114 passed, clippy/fmt clean. No new workspace deps.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
- tcp.rs: Aura proto handshake + Session directly over TcpStream (TcpServer/
TcpClient/TcpConnection: PacketConnection), with an optional light HTTP/1.1
masquerade preamble. Fallback for UDP-blocking networks. (Full TLS-443 mimicry
is a documented follow-up.)
- dial.rs: TransportMode {Udp,Tcp,Quic}, Endpoints, DialConfig; client `dial()`
tries transports in order and hands over on failure/timeout; MultiServer binds
and accepts on every enabled transport at once (TCP/QUIC multi-client; UDP
single-peer-per-accept in v1).
- Tests: tcp loopback (plain + masquerade), dial handover (dead TCP -> UDP).
clippy/fmt clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Aura's own data path over plain UDP, authenticated solely by the existing Aura
PQ handshake (hybrid X25519+ML-KEM-768 + mutual X.509) — no QUIC, no outer TLS.
- One UDP socket, two phases by type byte: 0x01 HS (reliable handshake), 0x02
DATA (datagram records). HS = DTLS-flight reliability over UDP: per-message
seq, cumulative acks, retransmit (RTO), reorder/dedup, post-handshake linger;
message boundaries parsed from the 5-byte Aura header. DATA = one explicit-
nonce AEAD record per datagram (seq||AEAD), replay-checked, optional padding to
HTTPS size buckets (obfuscation).
- UdpServer/UdpClient/UdpConnection (impl PacketConnection, concurrent send/recv).
v1: single peer per accept (multi-client demux is a follow-up).
- 5 adapter unit tests + udp loopback end-to-end (obfuscation on, 1300B/empty/
duplex) + handshake-survives-30%-loss-and-reorder. No new deps. QUIC tests
preserved. Whole workspace builds; clippy/fmt clean.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Contract for the custom UDP transport (v2):
- aura-crypto: AeadKey — ChaCha20-Poly1305 with an EXPLICIT per-message nonce
(caller passes the counter), for datagram transports where packets may be lost
or reordered. AeadSession::into_parts() hands off (AeadKey, counter). Same
nonce scheme as AeadSession, so they interoperate on one key with disjoint
counter ranges. +4 tests.
- aura-proto: DatagramSender/DatagramReceiver (record = seq(8) || AEAD(frame,
aad=seq), sliding replay window) and Session::into_datagram_parts(); reuse for
a UDP data path. +1 test. Existing 16 crypto / 13 proto tests still green.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
aura-cli: clap command tree (pki init/issue-server/issue-client/revoke/list,
server, client, route add/list/remove, status, bench-crypto); TOML config with
~ expansion and split-tunnel rules -> RouteTable; JSON-over-Unix-socket admin
IPC; server/client data paths wiring transport + tunnel (TUN run needs root).
config/{server,client}.toml.example. 15 tests (pki roundtrip, config parse,
admin-socket roundtrip, loopback connection). Verified the real binary: --help,
bench-crypto, and a full CA->server->client cert workflow.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Worktree isolation is unavailable in this environment, so make Wave 3 safe for
same-tree parallel work instead: the PacketConnection contract now lives in
aura-proto (stable) and aura-tunnel no longer depends on aura-transport. With
transport and tunnel both depending only on proto (and not each other), the two
crates are independent leaves and can be built/edited concurrently without one
breaking the other's build. proto: 13 tests still green.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Define the async PacketConnection trait (send_packet/recv_packet over &self)
that aura-tunnel's router consumes and the QUIC connection will implement.
Committed before Wave 3 so the transport and tunnel agents build against a
stable cross-crate contract from isolated worktrees.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Compose Session from SessionSender (writer + outbound AEAD/seq) and
SessionReceiver (reader + inbound AEAD + replay window); split() hands back
the two halves so a VPN data path can run concurrent read/write tasks
(recv_frame is not cancellation-safe, so select! on one &mut Session is unsafe).
send_frame/recv_frame/peer_id/into_inner unchanged; 13 tests still green.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
- 6-crate Cargo workspace, dependency tree frozen (cargo check green in ~1m)
- ml-kem 0.3 (FIPS 203) replaces spec's pqcrypto-kyber for ML-KEM-768
- fix invalid target-gated workspace.dependencies: Windows deps (wintun/windows)
declared untargeted, cfg-gated per-crate in aura-tunnel
- version bumps vs spec: tun 0.8, rcgen 0.14, wintun 0.5
- stub lib/main per crate; real implementations land wave by wave
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
xah30