IPMon - IP Address Monitor

IPMon is a network interface monitor that tracks IP address changes and automatically updates various network services configurations. It supports both IPv4 and IPv6 addresses and provides real-time updates to NFTables rules and proxy configurations.

Features

• Real-time monitoring of IPv4 and IPv6 address changes
• Automatic NFTables rule updates with named sets support
• Proxy configuration management
• Atomic file updates
• Configurable update delay with debouncing
• Thread-safe operation
• Graceful error handling
• Comprehensive logging

Architecture

flowchart TD
    Start([Start]) --> ParseArgs[Process Command Line Arguments]
    ParseArgs --> InitSocket[Initialize Unix Socket]
    InitSocket --> IsStart{Start Option?}
    IsStart -->|Yes| Update[Update Interface Info]
    IsStart -->|No| ListenThread
    Update --> ListenThread[Start Socket Listener Thread]
    ListenThread --> MonitorLoop[Enter Monitoring Loop]
    
    subgraph MonitorLoop [Netlink Monitoring Loop]
        direction TB
        RecvMsg[Receive Netlink Message] --> TimerActive{Timer Active?}
        TimerActive -->|Yes| CheckTime{Time Elapsed?}
        TimerActive -->|No| StartTimer[Start Timer]
        StartTimer --> RecvMsg
        CheckTime -->|Yes| TriggerUpdate[Trigger Update]
        CheckTime -->|No| RecvMsg
        TriggerUpdate --> RecvMsg
    end


    subgraph UpdateProcess [Update Process]
        direction TB
        GetAddrs[Get Interface Addresses] --> NFT{NFTables Option?}
        NFT -->|Yes| UpdateNFT[Update NFTables]
        NFT -->|No| Proxy{Proxy Option?}
        UpdateNFT --> Proxy
        Proxy -->|Yes| UpdateProxy[Update Proxy]
        Proxy -->|No| Monitor{Monitor Option?}
        UpdateProxy --> Monitor
        Monitor -->|Yes| PrintInfo[Print Interface Info]
    end

    MonitorLoop --> UpdateProcess

Loading

Prerequisites

Required packages:

sudo apt install libnftables-dev libjsoncpp-dev clang cmake pkg-config build-essential

Building

Using CMake

mkdir build && cd build
cmake ..
cmake --build .

Building Debian Package

mkdir build && cd build
cmake ..
cmake --build .
cpack

Installation

From Package (Recommended)

sudo dpkg -i ipmon_<version>_amd64.deb

From Source

mkdir build && cd build
cmake ..
cmake --build .
sudo cmake --install .

Usage

Basic command syntax:

ipmon [-n[FILE] | --nftables[=FILE] [-f | --flush]] [-p[FILE] | --proxy[=FILE]]
      [-d DELAY | --delay=DELAY] [-m | --monitor] [-h | --help]
      [-s | --start]

Options:

• -h, --help: Display help message
• -n, --nftables: Update NFTables addresses
• -f, --flush: Flush and reload NFTables ruleset
• -p, --proxy: Update proxy configuration
• -d, --delay: Set update delay (1-99 seconds or 100-999999 microseconds)
• -m, --monitor: Enable monitoring mode
• -s, --start: Update addresses at startup

Example Usage

Monitor and update NFTables with flush:

ipmon -n --flush

Monitor and update proxy with custom delay:

ipmon -p --delay=500000

Monitor all services with debugging:

ipmon -n -p -m --start

Configuration Files

Default configuration directory:

• /etc/impon

NFTables Configuration

Two configuration files are maintained:

1. Variables file (/etc/ipmon/ifacesAddrs.vars):

#!/usr/sbin/nft -f
define enp0s3 = { 192.168.150.52 }
define enp0s8 = { 192.168.56.2, 192.168.56.3 }

2. Sets file (/etc/ipmon/ifacesAddrs.sets):

#!/usr/sbin/nft -f
set enp0s3_ipv4_address { type ipv4_addr; elements = { 192.168.150.52 } }
set enp0s8_ipv4_address { type ipv4_addr; elements = { 192.168.56.2 } }

Service Integration

IPMon integrates with system services through:

• Systemd service management
• Unix domain sockets located at /run/ipmon.sock for IPC
• Atomic file updates
• Service-specific configuration formats

Troubleshooting

Common issues:

1. Service Updates Failing

   • Verify root privileges
   • Check service status: systemctl status ipmon
   • Review logs: journalctl -u ipmon

2. Address Updates Not Detected

   • Verify netlink socket status
   • Check interface status: ip addr
   • Enable monitoring: ipmon -m

3. Permission Issues

   • Check file permissions in /etc/ipmon/
   • Verify socket permissions in /run/ipmon.sock

Development

The project uses modern C++20 features and follows these practices:

• RAII for resource management
• Thread-safe operations
• Exception-safe code
• Comprehensive error handling
• Atomic operations for file updates

Building Debug Version

mkdir build-debug && cd build-debug
cmake -DCMAKE_BUILD_TYPE=Debug ..
cmake --build .

License

This project is licensed under the GNU General Public License v3.0 (GPL-3.0).

Read more at LICENSE.