rneter
rneter is a Rust library for managing SSH connections to network devices with intelligent state machine handling. It provides a high-level API for connecting to network devices (routers, switches, etc.), executing commands, and managing device states with automatic prompt detection and mode switching.
Features
- Connection Pooling: Automatically caches and reuses SSH connections for better performance
- State Machine Management: Intelligent device state tracking and automatic transitions
- Prompt Detection: Automatic prompt recognition and handling across different device types
- Mode Switching: Seamless transitions between device modes (user mode, enable mode, config mode, etc.)
- SFTP File Uploads: Upload local files to remote hosts that expose the SSH
sftpsubsystem - CLI SCP/TFTP Transfers: Drive supported network devices through interactive
copy scp:/copy tftp:workflows - Maximum Compatibility: Supports a wide range of SSH algorithms including legacy protocols for older devices
- Async/Await: Built on Tokio for high-performance asynchronous operations
- Error Handling: Comprehensive error types with detailed context
Installation
Add this to your Cargo.toml:
[]
= "0.3"
Quick Start
use ;
use templates;
async
Linux Server Management
rneter supports Linux server management with flexible privilege escalation:
use ;
use ;
async
LinuxTemplateConfig.shell_flavor defaults to DeviceShellFlavor::Posix. If the remote login shell is fish, set it explicitly to DeviceShellFlavor::Fish.
Custom Configuration:
use DeviceShellFlavor;
use ;
// Use sudo -s instead of sudo -i
let config = LinuxTemplateConfig ;
let handler = linux_with_config?;
// Custom prompt patterns
let config = LinuxTemplateConfig ;
let handler = linux_with_config?;
// Force fish-compatible exit-status capture
let config = LinuxTemplateConfig ;
let handler = linux_with_config?;
File Uploads
If the remote host enables the SSH sftp subsystem, rneter can upload local files over the
same authenticated SSH connection:
use ;
use templates;
async
This path requires SFTP support on the remote host. For devices that only expose CLI-driven
transfer commands such as copy scp: or copy tftp:, continue using the existing command API.
Network Device SCP/TFTP Transfers
For supported Cisco-like templates, rneter can also drive device-side copy scp: and
copy tftp: workflows by auto-answering the interactive prompts:
use ;
use templates;
async
Built-in CLI transfer workflows currently target cisco, arista, chaitin, maipu, and
venustech. Other templates can still support transfers by building custom commands and prompt
rules on top of the same command execution API.
Security Levels
rneter now supports secure defaults and configurable SSH security levels when connecting:
use ;
use templates;
// Secure by default (uses known_hosts verification + strict algorithms)
let _sender = MANAGER
.get_with_context
.await?;
// Explicitly choose a security profile
let _sender = MANAGER
.get_with_context
.await?;
Session Recording and Replay
use ;
use templates;
let = MANAGER
.get_with_recording_level_and_context
.await?;
// Subscribe to future recorder events in real time
let mut rx = recorder.subscribe;
spawn;
// Or record key events only (no raw shell chunks)
let = MANAGER
.get_with_recording_level_and_context
.await?;
// ...send CmdJob through `sender`...
// Export recording as JSONL
let jsonl = recorder.to_jsonl?;
// Restore and replay offline
let restored = from_jsonl?;
let mut replayer = from_recorder;
let replayed_output = replayer.replay_next?;
println!;
// Offline command-flow testing without real SSH
let script = vec!;
let outputs = replayer.replay_script?;
assert_eq!;
Transactional Command Blocks
For configuration commands, you can execute a block with commit-or-rollback behavior:
use ;
use templates;
let block = TxBlock ;
let result = MANAGER
.execute_tx_block_with_context
.await?;
println!;
For multi-block all-or-nothing workflows (for example addresses -> services -> policy):
use ;
let workflow = TxWorkflow ;
let workflow_result: TxWorkflowResult = MANAGER
.execute_tx_workflow_with_context
.await?;
for block in &workflow_result.block_results
You can also build blocks from template strategies:
let cmds = vec!;
let block = build_tx_block?;
For CI-style offline tests, you can store JSONL recordings under tests/fixtures/
and replay them in integration tests (see tests/replay_fixtures.rs).
To normalize noisy online recordings into stable fixtures:
Template and State-Machine Ecosystem
You can manage built-in templates as a catalog and run state-graph diagnostics:
use templates;
let names = available_templates;
assert!;
let _handler = by_name?; // case-insensitive
let report = diagnose_template?;
println!;
println!;
let catalog = template_catalog;
println!;
let all_json = diagnose_all_templates_json?;
println!;
You can also export a built-in template configuration, extend it, and build your own handler:
use prompt_rule;
use templates;
let mut config = by_name_config?;
config
.prompt
.push;
let handler = config.build?;
assert!;
New recording/replay capabilities:
- Prompt tracking: each
command_outputnow records bothprompt_before/prompt_after - FSM prompt tracking: each event can include
fsm_prompt_before/fsm_prompt_after - Output prompt: command/replay results now include
Output.prompt - Transaction lifecycle recording:
tx_block_started,tx_step_succeeded,tx_step_failed,tx_rollback_started,tx_rollback_step_succeeded,tx_rollback_step_failed,tx_block_finished - Schema compatibility: legacy
connection_establishedfields (prompt/state) remain readable - Fixture quality workflow:
tests/fixtures/includes success/failure/state-switch samples and snapshot checks intests/replay_fixtures.rs
Example command_output event shape:
Example transaction lifecycle event shape:
Architecture
Connection Management
The SshConnectionManager provides a singleton connection pool accessible via the MANAGER constant. It automatically:
- Caches connections for 5 minutes of inactivity
- Reconnects on connection failure
- Manages up to 100 concurrent connections
State Machine
The DeviceHandler implements a finite state machine that:
- Tracks the current device state using regex patterns
- Finds optimal paths between states using BFS
- Handles automatic state transitions
- Supports system-specific states (e.g., different VRFs or contexts)
Design Rationale
The state machine is designed around two stable facts in network-device automation:
- Prompts are more reliable than command text for identifying current mode.
- Transition paths vary by vendor/model, so pathfinding must be data-driven.
Core design choices:
- Normalize states to lowercase and map prompt regex matches to state indexes for fast lookups.
- Separate prompt detection (
read_prompt) from state update (read) to keep command loops predictable. - Model transitions as a directed graph (
edges) and use BFS to find shortest valid mode switch path. - Keep dynamic input handling (
read_need_write) independent from command logic, so password/confirm flows are reusable. - Track both CLI prompt text and FSM prompt (state name) to support online diagnostics and offline replay assertions.
Benefits:
- Better portability: vendor-specific behavior is mostly data configuration, not hard-coded branches.
- Better resilience: command execution relies on prompt/state convergence instead of fixed output formats.
- Better testability: record/replay can validate state transitions and prompt evolution without real SSH sessions.
State Transition Model
flowchart LR
O["Output"] --> L["Login Prompt"]
L -->|enable| E["Enable Prompt"]
E -->|configure terminal| C["Config Prompt"]
C -->|exit| E
E -->|exit| L
E -->|show ...| E
C -->|show ... / set ...| C
Command Execution Flow (State-Aware)
flowchart TD
A["Receive Command(mode, command, timeout)"] --> B["Read current FSM prompt/state"]
B --> C["BFS transition planning: trans_state_write(target_mode)"]
C --> D["Execute transition commands sequentially"]
D --> E["Execute target command"]
E --> F["Read stream chunks -> update handler.read(line)"]
F --> G{"Prompt matched?"}
G -->|No| F
G -->|Yes| H["Build Output(success, content, all, prompt)"]
H --> I["Record event: prompt_before/after + fsm_prompt_before/after"]
Command Execution
Commands are executed through an async channel-based architecture:
- Submit a
CmdJobto the connection sender - The library automatically transitions to the target state if needed
- Executes the command and waits for the prompt
- Returns the output with success status
Supported Device Types
The library is designed to work with any SSH-enabled network device and Linux servers. It's particularly well-suited for:
Network Devices:
- Cisco IOS/IOS-XE/IOS-XR devices
- Juniper JunOS devices
- Arista EOS devices
- Huawei VRP devices
- H3C Comware devices
- Hillstone SG devices
- Array Networks APV devices
- Fortinet FortiGate firewalls
- Palo Alto Networks PA firewalls
- Check Point Security Gateway
- Topsec NGFW firewalls
- Venustech USG devices
- DPTech firewall devices
- Chaitin SafeLine gateways
- QiAnXin NSG gateways
- Maipu network devices
Linux Servers:
- Generic Linux distributions (Ubuntu, Debian, CentOS, RHEL, etc.)
- Supports multiple privilege escalation methods (sudo -i, sudo -s, su, direct root)
- Intelligent prompt detection with customizable patterns
- Transaction-based configuration management with rollback support
Configuration
SSH Algorithm Support
rneter includes comprehensive SSH algorithm support in the config module:
- Key exchange: Curve25519, DH groups, ECDH
- Ciphers: AES (CTR/CBC/GCM), ChaCha20-Poly1305
- MAC: HMAC-SHA1/256/512 with ETM variants
- Host keys: Ed25519, ECDSA, RSA, DSA (for legacy devices)
This ensures maximum compatibility with both modern and legacy network equipment.
Error Handling
The library provides detailed error types through ConnectError:
UnreachableState: Target state cannot be reached from current stateTargetStateNotExistError: Requested state doesn't exist in configurationChannelDisconnectError: SSH channel disconnected unexpectedlyExecTimeout: Command execution exceeded timeout- And more...
Documentation
For detailed API documentation, visit docs.rs/rneter.
License
This project is licensed under the MIT License - see the LICENSE file for details.
Contributing
Contributions are welcome! Please feel free to submit a Pull Request.
Author
demohiiiii