TrustTunnel/CONFIGURATION.md

TrustTunnel Endpoint Configuration

This document describes all available configuration settings and configuration files for the TrustTunnel VPN endpoint.

Table of Contents

• Overview
• Command Line Arguments
• Configuration Files
  • Main Settings File (vpn.toml)
  • TLS Hosts Settings File (hosts.toml)
  • Credentials File (credentials.toml)
  • Rules File (rules.toml)
• Settings Reference
  • Core Settings
  • Listen Protocol Settings
  • Forward Protocol Settings
  • Reverse Proxy Settings
  • ICMP Settings
  • Metrics Settings
• TLS Hosts Reference
• Rules Reference
• Runtime Configuration

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Overview

The TrustTunnel endpoint uses TOML-formatted configuration files. The main configuration is split into:

1. Main settings file - Core endpoint configuration (timeouts, protocols, etc.)
2. TLS hosts settings file - TLS certificate and hostname configuration
3. Credentials file - Client authentication credentials
4. Rules file - Connection filtering rules

The setup_wizard tool can generate these files interactively.

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Command Line Arguments

The endpoint binary accepts the following command line arguments:

Argument	Short	Description	Default
--version	-v	Print version and exit	-
--loglvl	-l	Logging level (info, debug, trace)	info
--logfile	-	File path for storing logs (stdout if not specified)	stdout
--sentry_dsn	-	Sentry DSN for error reporting	-
--jobs	-	Number of worker threads (defaults to CPU count)	CPU count
<settings>	-	Required. Path to main settings file	-
<tls_hosts_settings>	-	Required. Path to TLS hosts settings file	-
--client_config	-c	Print endpoint config for specified client and exit	-
--address	-a	Endpoint address to add to client config (requires -c). Accepts ip, ip:port, domain, or domain:port.	-

Examples

# Start the endpoint
./trusttunnel_endpoint vpn.toml hosts.toml

# Start with debug logging
./trusttunnel_endpoint vpn.toml hosts.toml -l debug

# Start with file logging
./trusttunnel_endpoint vpn.toml hosts.toml --logfile /var/log/trusttunnel.log

# Export client configuration with IP address
./trusttunnel_endpoint vpn.toml hosts.toml -c username -a 203.0.113.1

# Export client configuration with explicit port
./trusttunnel_endpoint vpn.toml hosts.toml -c username -a 203.0.113.1:443

# Export client configuration with domain name
./trusttunnel_endpoint vpn.toml hosts.toml -c username -a vpn.example.com

# Export client configuration with domain name and explicit port
./trusttunnel_endpoint vpn.toml hosts.toml -c username -a vpn.example.com:443

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Configuration Files

Main Settings File (vpn.toml)

The main settings file contains core endpoint configuration. Example:

# The address to listen on
listen_address = "0.0.0.0:443"

# Whether IPv6 connections can be routed
ipv6_available = true

# Whether connections to private network of the endpoint are allowed
allow_private_network_connections = false

# Timeout of an incoming TLS handshake (seconds)
tls_handshake_timeout_secs = 10

# Timeout of a client listener (seconds)
client_listener_timeout_secs = 600

# Timeout of outgoing connection establishment (seconds)
connection_establishment_timeout_secs = 30

# Idle timeout of tunneled TCP connections (seconds)
tcp_connections_timeout_secs = 604800

# Timeout of tunneled UDP "connections" (seconds)
udp_connections_timeout_secs = 300

# Path to credentials file
credentials_file = "credentials.toml"

# Path to rules file (optional)
rules_file = "rules.toml"

# Listen protocol settings
[listen_protocols]

[listen_protocols.http1]
upload_buffer_size = 32768

[listen_protocols.http2]
initial_connection_window_size = 8388608
initial_stream_window_size = 131072
max_concurrent_streams = 1000
max_frame_size = 16384
header_table_size = 65536

[listen_protocols.quic]
recv_udp_payload_size = 1350
send_udp_payload_size = 1350
initial_max_data = 104857600
initial_max_stream_data_bidi_local = 1048576
initial_max_stream_data_bidi_remote = 1048576
initial_max_stream_data_uni = 1048576
initial_max_streams_bidi = 4096
initial_max_streams_uni = 4096
max_connection_window = 25165824
max_stream_window = 16777216
disable_active_migration = true
enable_early_data = true
message_queue_capacity = 4096

# Forward protocol (optional, defaults to direct)
[forward_protocol]
direct = {}

# Reverse proxy settings (optional)
# [reverse_proxy]
# server_address = "127.0.0.1:8080"
# path_mask = "/api"
# h3_backward_compatibility = false

# ICMP settings (optional, requires superuser)
# [icmp]
# interface_name = "eth0"
# request_timeout_secs = 3
# recv_message_queue_capacity = 256

# Metrics settings (optional)
# [metrics]
# address = "127.0.0.1:1987"
# request_timeout_secs = 3

TLS Hosts Settings File (hosts.toml)

Configures TLS certificates and hostnames. Example:

# Main TLS hosts for traffic tunneling
[[main_hosts]]
hostname = "vpn.example.com"
cert_chain_path = "certs/cert.pem"
private_key_path = "certs/key.pem"

# Ping hosts for HTTPS health checks (optional)
[[ping_hosts]]
hostname = "ping.vpn.example.com"
cert_chain_path = "certs/cert.pem"
private_key_path = "certs/key.pem"

# Speed test hosts (optional)
[[speedtest_hosts]]
hostname = "speed.vpn.example.com"
cert_chain_path = "certs/cert.pem"
private_key_path = "certs/key.pem"

# Reverse proxy hosts (optional, requires reverse_proxy in main settings)
# [[reverse_proxy_hosts]]
# hostname = "api.example.com"
# cert_chain_path = "certs/cert.pem"
# private_key_path = "certs/key.pem"

Credentials File (credentials.toml)

Contains client authentication credentials. Example:

[[client]]
username = "user1"
password = "secure_password_1"

[[client]]
username = "user2"
password = "secure_password_2"

Rules File (rules.toml)

Defines connection filtering rules. Example:

# Rules are evaluated in order, first matching rule's action is applied.
# If no rules match, the connection is allowed by default.

# Deny connections from specific IP range
[[rule]]
cidr = "192.168.1.0/24"
action = "deny"

# Allow connections with specific TLS client random prefix
[[rule]]
client_random_prefix = "aabbcc"
action = "allow"

# Deny connections matching both IP and client random with mask
[[rule]]
cidr = "10.0.0.0/8"
client_random_prefix = "a0b0/f0f0"
action = "deny"

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Settings Reference

Core Settings

Setting	Type	Default	Description
listen_address	String	0.0.0.0:443	Address and port to listen on
ipv6_available	Boolean	true	Whether IPv6 connections can be routed
allow_private_network_connections	Boolean	false	Allow connections to endpoint's private network
tls_handshake_timeout_secs	Integer	10	TLS handshake timeout in seconds
client_listener_timeout_secs	Integer	600	Client listener timeout in seconds (10 minutes)
connection_establishment_timeout_secs	Integer	30	Outgoing connection timeout in seconds
tcp_connections_timeout_secs	Integer	604800	Idle TCP connection timeout (1 week)
udp_connections_timeout_secs	Integer	300	UDP connection timeout (5 minutes)
credentials_file	String	-	Path to credentials file
rules_file	String	-	Path to rules file (optional)

Listen Protocol Settings

Configure which protocols the endpoint accepts. At least one protocol must be enabled.

HTTP/1.1 Settings ([listen_protocols.http1])

Setting	Type	Default	Description
upload_buffer_size	Integer	32768	Buffer size for outgoing traffic (bytes)

HTTP/2 Settings ([listen_protocols.http2])

Setting	Type	Default	Description
initial_connection_window_size	Integer	8388608	Connection-level flow control window (8 MB)
initial_stream_window_size	Integer	131072	Stream-level flow control window (128 KB)
max_concurrent_streams	Integer	1000	Maximum concurrent streams
max_frame_size	Integer	16384	Maximum HTTP/2 frame payload size
header_table_size	Integer	65536	Maximum header frame size

QUIC/HTTP/3 Settings ([listen_protocols.quic])

Setting	Type	Default	Description
recv_udp_payload_size	Integer	1350	Maximum received UDP payload size
send_udp_payload_size	Integer	1350	Maximum sent UDP payload size
initial_max_data	Integer	104857600	Initial max connection data (100 MB)
initial_max_stream_data_bidi_local	Integer	1048576	Local bidirectional stream flow control (1 MB)
initial_max_stream_data_bidi_remote	Integer	1048576	Remote bidirectional stream flow control (1 MB)
initial_max_stream_data_uni	Integer	1048576	Unidirectional stream flow control (1 MB)
initial_max_streams_bidi	Integer	4096	Maximum bidirectional streams
initial_max_streams_uni	Integer	4096	Maximum unidirectional streams
max_connection_window	Integer	25165824	Maximum connection window (24 MB)
max_stream_window	Integer	16777216	Maximum stream window (16 MB)
disable_active_migration	Boolean	true	Disable active connection migration
enable_early_data	Boolean	true	Enable 0-RTT early data
message_queue_capacity	Integer	4096	QUIC multiplexer queue capacity

Forward Protocol Settings

Configure how the endpoint forwards connections.

Direct Forwarding (default)

[forward_protocol]
direct = {}

Routes connections directly to target hosts.

SOCKS5 Forwarding

[forward_protocol.socks5]
address = "127.0.0.1:1080"
extended_auth = false

Setting	Type	Default	Description
address	String	-	Required. SOCKS5 proxy address
extended_auth	Boolean	false	Enable extended authentication

Reverse Proxy Settings

Optional. Enables TLS termination and HTTP protocol translation.

[reverse_proxy]
server_address = "127.0.0.1:8080"
path_mask = "/api"
h3_backward_compatibility = false

Setting	Type	Default	Description
server_address	String	-	Required. Origin server address
path_mask	String	-	Required. Path prefix for routing (must start with /)
h3_backward_compatibility	Boolean	false	Override HTTP method for H3→H1 translation

The reverse proxy translates HTTP/x traffic to HTTP/1.1 towards the origin server. Translated requests include the X-Original-Protocol header (HTTP1 or HTTP3).

ICMP Settings

Optional. Enables ICMP forwarding. Requires superuser privileges on some systems.

[icmp]
interface_name = "eth0"
request_timeout_secs = 3
recv_message_queue_capacity = 256

Setting	Type	Default	Description
interface_name	String	eth0 (Linux) / en0 (macOS)	Network interface for ICMP socket
request_timeout_secs	Integer	3	ICMP request timeout in seconds
recv_message_queue_capacity	Integer	256	Message queue capacity per client

Metrics Settings

Optional. Enables Prometheus-compatible metrics endpoint.

[metrics]
address = "127.0.0.1:1987"
request_timeout_secs = 3

Setting	Type	Default	Description
address	String	127.0.0.1:1987	Metrics endpoint address
request_timeout_secs	Integer	3	Request timeout in seconds

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TLS Hosts Reference

Each TLS host entry requires:

Field	Type	Description
hostname	String	Required. Hostname for TLS SNI matching (must be unique)
cert_chain_path	String	Required. Path to PEM certificate chain file
private_key_path	String	Required. Path to PEM private key file

Host Types

• main_hosts - Primary hosts for VPN traffic tunneling and service requests
• ping_hosts - Respond with 200 OK to HTTPS GET requests (health checks)
• speedtest_hosts - Handle speed test requests:
  • GET /Nmb.bin (N=1-100): Download N megabytes
  • POST /upload.html: Upload test (up to 120 MB)
• reverse_proxy_hosts - Forward to reverse proxy server (requires [reverse_proxy])

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Rules Reference

Rules filter incoming connections based on client IP and/or TLS client random data.

Rule Structure

[[rule]]
cidr = "192.168.0.0/16"           # Optional: IP range in CIDR notation
client_random_prefix = "aabbcc"   # Optional: Hex-encoded prefix or prefix/mask
action = "allow"                  # Required: "allow" or "deny"

Evaluation

1. Rules are evaluated in order
2. First matching rule's action is applied
3. If no rules match, connection is allowed by default
4. If both cidr and client_random_prefix are specified, both must match

Client Random Matching

Two formats are supported:

Simple prefix matching:

client_random_prefix = "aabbcc"

Matches if TLS client random starts with 0xaabbcc.

Bitwise matching with mask:

client_random_prefix = "a0b0/f0f0"

Matches if (client_random & 0xf0f0) == (0xa0b0 & 0xf0f0).

Examples

# Block specific IP range
[[rule]]
cidr = "192.168.1.0/24"
action = "deny"

# Allow specific client random prefix
[[rule]]
client_random_prefix = "deadbeef"
action = "allow"

# Block internal networks with specific client signature
[[rule]]
cidr = "10.0.0.0/8"
client_random_prefix = "bad0/ff00"
action = "deny"

# Catch-all deny (place last)
[[rule]]
action = "deny"

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Runtime Configuration

Hot Reloading TLS Hosts

Send SIGHUP to the endpoint process to reload TLS hosts settings without restart:

kill -HUP $(pidof trusttunnel_endpoint)

This reloads the TLS hosts settings file specified at startup.

Systemd Service

A systemd service template is provided. Default configuration assumes files in /opt/trusttunnel/:

# Install service
sudo cp /opt/trusttunnel/trusttunnel.service.template /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now trusttunnel

# Reload TLS settings
sudo systemctl reload trusttunnel

# View logs
sudo journalctl -u trusttunnel -f

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See Also

• README.md - Quick start guide
• DEVELOPMENT.md - Development documentation
• PROTOCOL.md - Protocol specification
• CHANGELOG.md - Changelog