SimpleSyslogServer

A lightweight syslog server implementation in Go that supports both TCP and UDP protocols. This server can filter messages based on IP addresses, severity levels, and content patterns.

Features

• Supports both TCP and UDP syslog protocols
• Configurable message filtering:
  • IP-based filtering with CIDR support
  • Severity level filtering
  • Content pattern exclusion
• Configurable output:
  • File logging
  • Console output
• YAML-based configuration

Prerequisites

• Go 1.23 or higher
• Basic understanding of syslog protocol

Installation

1. Clone the repository:

git clone https://github.com/yourusername/SimpleSyslogServer.git
cd SimpleSyslogServer

2. Build the server:

go build -o syslog-server

Configuration

The server is configured using config.yaml. Here's an example configuration:

server:
  port: 514
  log_file: "syslog.log"  # Leave empty for no file logging
  console_output: true    # Set to false to disable console output

filter:
  enabled: False          # Set to false to disable all filtering
  allowed_ips:
    - "127.0.0.0/8"      # Localhost range
    - "192.168.0.0/24"   # Local network
    - "0.0.0.0/0"        # All IPs
  min_severity: 7        # 0=Emergency, 7=Debug
  exclude_patterns:
    - "test"
    - "debug"

Configuration Options

Server Settings

• port: The port number to listen on (default: 514)
• log_file: Path to the log file (empty for no file logging)
• console_output: Enable/disable console output

Filter Settings

• enabled: Enable/disable all filtering
• allowed_ips: List of allowed IP addresses/ranges in CIDR notation
• min_severity: Minimum severity level to accept (0-7)
  • 0: Emergency
  • 1: Alert
  • 2: Critical
  • 3: Error
  • 4: Warning
  • 5: Notice
  • 6: Informational
  • 7: Debug
• exclude_patterns: List of patterns to exclude from logging

Usage

1. Start the server:

./syslog-server

2. Configure your syslog clients to send logs to the server:

# Example using logger command
logger -n localhost -P 514 "Test message"

Testing

You can test the server using the logger command or any syslog client:

# Test UDP
logger -n localhost -P 514 -d "Test UDP message"

# Test TCP
logger -n localhost -P 514 -T "Test TCP message"

License

This project is licensed under the terms of the included LICENSE file.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.