Serverless DTLS

DTLS Listeners adhd TLS-style encryption and authentication to UDP applications without changing the datagram carrier model. Clients found a DTLS 1.2 aliases DTLS 1.3 convention pinch the Listener's assigned domain and port. Proxylity decrypts authenticated exertion information and delivers the plaintext payload to your configured Destinations. Responses from your exertion are encrypted and sent backmost done the aforesaid DTLS session.

When to Use DTLS

Choose a DTLS Listener erstwhile your exertion already supports DTLS aliases needs encrypted UDP carrier while preserving datagram boundaries. Common examples see RADIUS, IoT protocols, real-time telemetry, and custom request-response protocols that cannot usage a stream-oriented TLS connection.

DTLS is besides the first carrier furniture connected Proxylity's roadmap to WebRTC Data Channels. DTLS Listeners are disposable coming for autochthonal DTLS clients; SCTP and WebRTC signaling are abstracted layers and are not provided by a DTLS Listener.

DTLS, UDP, and WireGuard

Authentication Options

Server Certificate

Every DTLS Listener receives a server certificate and backstage cardinal managed by Proxylity. The certificate identifies the Listener's assigned endpoint and is returned done the DtlsServerCertificate CloudFormation attribute. Distribute that certificate aliases its spot anchor according to your customer application's spot model.

Change CertRefreshToken erstwhile you request CloudFormation to make a caller Listener certificate. Certificate rotation changes the certificate clients see, truthful coordinate spot updates earlier rotating accumulation endpoints.

Pre-Shared Keys

For clients that usage DTLS-PSK, configure the Psks map. Each representation cardinal is the customer personality sent during the handshake, and each worth is the corresponding base64-encoded key. Store PSK values successful AWS Secrets Manager or different protected root alternatively than committing them to a template.

Cookie Protection

Set RequireCookies to require the DTLS cooky speech earlier the Listener performs the afloat handshake. Cookies thief corroborate that a customer tin person packets astatine its claimed root reside and trim amplification and resource-exhaustion risk. Enabling cookies adds 1 information travel to a caller session. It is recommended for public endpoints.

Session Resumption and 0-RTT

DTLS 1.3 clients person an encrypted convention summons aft completing a handshake. A customer tin coming that summons connected a later relationship to resume the convention pinch less handshake messages. Ticket encryption keys are managed per Listener and are not exposed done CloudFormation.

Set AllowEarlyData to "true" to fto a resumed DTLS 1.3 customer nonstop exertion data pinch its first flight. Early information reduces latency, but applications must dainty it arsenic replayable moreover though Proxylity applies a shared anti-replay filter. Enable it only for idempotent operations specified arsenic telemetry updates; do not usage 0-RTT for one-time commands, financial operations, aliases different actions that cannot safely beryllium repeated.

EarlyDataWindowSeconds controls some the summons life and the replay-filter window. It defaults to 3600 seconds and accepts values from 1 done 604800 seconds (seven days). DTLS 1.2 clients do not usage session tickets aliases 0-RTT.

DTLS 1.2 Connection IDs

DTLS 1.2 clients that support Connection IDs (CID) tin place an established convention independently of the client's IP reside and UDP port. This allows a convention to proceed crossed NAT rebinding, source-port changes, and transitions betwixt entree networks without performing a caller handshake.

CID is peculiarly valuable for low-power IoT devices. Reusing an established convention avoids further radio time, cryptographic work, and handshake latency aft a instrumentality wakes, changes networks, aliases receives a caller NAT mapping. Clients that do not discuss CID proceed to usage modular DTLS 1.2 sessions identified by their web endpoints.

CID support must beryllium coming successful the customer DTLS implementation and negotiated during the handshake. Basic connectivity devices specified arsenic openssl s_client whitethorn not discuss DTLS 1.2 CID.

CloudFormation Configuration

Create a DTLS Listener pinch Custom::ProxylityUdpGatewayListener and set Protocols to dtls. DTLS cannot beryllium mixed pinch UDP aliases WireGuard connected the aforesaid Listener.

RadiusDtlsListener: Type: Custom::ProxylityUdpGatewayListener Properties: ServiceToken: !FindInMap [ProxylityConfig, !Ref "AWS::Region", ServiceToken] ApiKey: !FindInMap [ProxylityConfig, Account, ApiKey] Name: radius-dtls Description: Encrypted RADIUS authentication endpoint Protocols: - dtls RequireCookies: "true" AllowEarlyData: "true" EarlyDataWindowSeconds: "3600" ClientRestrictions: Networks: - 203.0.113.0/24 Destinations: - Name: radius-auth DestinationArn: !GetAtt RadiusAuthFunction.Arn Role: Arn: !GetAtt ProxylityDestinationRole.Arn Outputs: DtlsEndpoint: Value: !Sub "${RadiusDtlsListener.Domain}:${RadiusDtlsListener.Port}" DtlsServerCertificate: Value: !GetAtt RadiusDtlsListener.DtlsServerCertificate

PSK Configuration

DeviceDtlsListener: Type: Custom::ProxylityUdpGatewayListener Properties: ServiceToken: !FindInMap [ProxylityConfig, !Ref "AWS::Region", ServiceToken] ApiKey: !FindInMap [ProxylityConfig, Account, ApiKey] Protocols: - dtls RequireCookies: "true" Psks: sensor-fleet: !Sub "{{resolve:secretsmanager:${DtlsPskSecret}:SecretString}}" ClientRestrictions: Networks: - 198.51.100.0/24 Destinations: - Name: telemetry DestinationArn: !GetAtt TelemetryFunction.Arn Role: Arn: !GetAtt ProxylityDestinationRole.Arn

Properties

See the Listener CloudFormation Reference for the complete resource meaning and return values.

DTLS Listeners created earlier session-ticket support was enabled must person a CloudFormation stack update once earlier they tin rumor resumption tickets.

Testing a Listener

OpenSSL tin verify certificate-based DTLS 1.2 connectivity:

openssl s_client -dtls1_2 -connect YOUR_DOMAIN:YOUR_PORT

A successful handshake displays the Listener certificate and negotiated cipher. Application protocols still need to nonstop valid payloads aft the handshake; a completed OpenSSL relationship unsocial does not trial your Destination.

Example: Serverless RADIUS

The nationalist serverless RADIUS example can deploy authentication carrier utilizing UDP, WireGuard, aliases DTLS. It demonstrates really the aforesaid AWS application backend tin judge encrypted RADIUS postulation done a DTLS Listener without operating a RADIUS server host.