How to integrate smoltcp into a Rust embedded project?

Add smoltcp as a dependency with no-std features, implement the PHY layer for your hardware, and configure settings via compile-time features like buffer sizes. The loopback example shows bare-metal usage without an OS.

smoltcp vs lwIP: which is better for embedded systems?

smoltcp is written in Rust with no heap allocation, offering memory safety and easy integration in Rust projects, while lwIP is C-based and more mature with broader feature support. Choose smoltcp for Rust ecosystems and lwIP for C compatibility.

Does smoltcp support DHCP for automatic IP configuration?

Yes, via the 'socket-dhcpv4' feature, enabling devices to obtain IP addresses dynamically. However, it requires proper network interface setup as described in the bridged connection example.

How to test smoltcp without real hardware?

Use the hosted examples on Linux with tap interfaces to simulate network traffic; the httpclient and server examples demonstrate this, but it's limited to Linux systems currently.

What's the memory footprint of smoltcp on a microcontroller?

Memory usage is configurable via compile-time settings like buffer counts and sizes; with minimal features, it can be very small, but must be tuned based on network demands, as detailed in the configuration section.

Can smoltcp handle secure connections with TLS/SSL?

No, smoltcp only provides the TCP/IP stack; you need to implement TLS on top using external crates like rustls, which adds complexity and memory overhead for secure communications.

Open-Awesome

smoltcp

0BSDRustv0.13.0

A standalone, event-driven TCP/IP stack for bare-metal, real-time systems written in Rust.

GitHub

4.5k stars546 forks0 contributors

What is smoltcp?

smoltcp is a standalone TCP/IP networking stack implemented in Rust for bare-metal and real-time systems. It provides a complete networking implementation without requiring an operating system or heap allocation, solving the problem of adding network connectivity to resource-constrained embedded devices. The stack supports Ethernet, IPv4, IPv6, TCP, UDP, and ICMP protocols with a focus on simplicity and reliability.

Target Audience

Embedded systems developers working on IoT devices, real-time systems, and bare-metal applications that require network connectivity without the overhead of a full operating system. Rust developers building networking infrastructure for constrained environments.

Value Proposition

Developers choose smoltcp because it's one of the few production-ready TCP/IP stacks written in Rust with zero heap allocation, making it ideal for safety-critical and resource-constrained applications. Its clean design, extensive documentation, and focus on robustness differentiate it from heavier alternatives like lwIP.

Overview

a smol tcp/ip stack

Use Cases

Best For

Adding network connectivity to bare-metal embedded systems
Building real-time systems with TCP/IP networking requirements
Creating IoT devices with constrained memory resources
Implementing custom network stacks for specialized hardware
Educational purposes for learning TCP/IP protocol implementation
Networking in Rust-based embedded projects without OS dependencies

Not Ideal For

Projects requiring advanced TCP optimizations like selective acknowledgements or PLPMTU for high-loss networks
Development on non-Linux systems where hosted testing is needed
Applications that already have a full OS with a built-in, optimized networking stack
Teams wanting plug-and-play network setup without manual interface configuration

Pros & Cons

Pros

No Heap Allocation

Uses only stack memory with zero dynamic allocation, critical for resource-constrained embedded systems, as emphasized in the no-std design and feature list.

Bare-Metal Compatibility

Runs without an operating system, ideal for IoT and real-time applications, confirmed by its design for bare-metal, no-OS environments.

Comprehensive Protocol Suite

Supports IPv4, IPv6, TCP, UDP, and 6LoWPAN with full dual-stack implementation, detailed in the IP and transport layer sections of the README.

High Performance Benchmarks

Achieves Gbps throughput in loopback tests against Linux TCP stack, demonstrated in the benchmark.rs example with real-world results.

Cons

Missing Advanced Features

Lacks selective acknowledgements, PLPMTU, and timestamping, which are important for TCP efficiency, as admitted in the TCP layer omissions list.

Linux-Only Hosted Support

Hosted usage examples currently only work on Linux, limiting cross-platform testing, stated in the 'Hosted usage examples' section.

Complex Manual Setup

Requires manual configuration of tap interfaces and routing for testing, which is tedious compared to higher-level libraries, as shown in the installation steps.

Frequently Asked Questions

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