A comprehensive, spec-compliant IGMP (Internet Group Management Protocol) library for Go, with CLI tools for querying and monitoring.

• Full IGMP v1/v2/v3 support -- marshal and unmarshal all message types
• Message types: Membership Query, Reports (v1/v2/v3), Leave Group
• IGMPv3 Group Records: all 6 record types (MODE_IS_INCLUDE, MODE_IS_EXCLUDE, CHANGE_TO_INCLUDE, CHANGE_TO_EXCLUDE, ALLOW_NEW_SOURCES, BLOCK_OLD_SOURCES)
• IGMPv3 floating-point encoding for Max Response Code and QQIC fields
• RFC-compliant: Router Alert IP option, DSCP CS6 TOS, TTL=1
• Raw socket abstraction with send and receive support
• Periodic querier with context-based lifecycle
• Passive listener for monitoring IGMP traffic
• Minimal dependencies: only golang.org/x/net for the library itself

• igmpqd -- lightweight IGMP query daemon (sends periodic IGMPv2/v3 queries)
• igmpmon -- real-time IGMP traffic monitor with full TUI dashboard

go install github.com/jmylchreest/igmp/cmd/igmpqd@latest
go install github.com/jmylchreest/igmp/cmd/igmpmon@latest

go get github.com/jmylchreest/igmp

package main

import (
    "fmt"
    "net"
    "time"

    "github.com/jmylchreest/igmp"
)

func main() {
    // Build an IGMPv2 General Query
    query := &igmp.MembershipQuery{
        MaxRespTime:  10 * time.Second,
        GroupAddress: net.IPv4zero,
    }
    data, _ := query.Marshal()
    fmt.Printf("Query: %x\n", data)

    // Parse an incoming IGMP message
    msg, _ := igmp.Parse(data)
    fmt.Printf("Type: %s, Version: %d\n",
        igmp.MessageTypeName(msg.Type()), msg.Version())

    // Build an IGMPv3 Membership Report
    report := &igmp.MembershipReportV3{
        GroupRecords: []igmp.GroupRecord{
            {
                RecordType:   igmp.RecordModeIsExclude,
                GroupAddress: net.IPv4(239, 1, 1, 1),
            },
        },
    }
    data, _ = report.Marshal()
    fmt.Printf("Report: %x\n", data)
}

# Send IGMPv2 General Queries every 30 seconds on eth0
sudo igmpqd run --interface eth0 --interval 30

# Send IGMPv3 queries with debug logging
sudo igmpqd run -I eth0 -V 3 --debug

# Group-specific query
sudo igmpqd run -I eth0 --grp-address 239.1.1.1 --dst-address 239.1.1.1

Flags:

Backward-compatible aliases (--grpAddress, --dstAddress, --maxResponseTime) are also supported.

# Monitor all IGMP traffic on eth0
sudo igmpmon --interface eth0

# Monitor on all interfaces
sudo igmpmon

The TUI dashboard shows:

• Statistics: packet counts, version breakdown, session duration
• Querier Status: detected querier IP, version, last seen
• Active Groups: multicast groups with member counts and status
• Packet Log: scrollable live feed of all IGMP packets

Press Enter on a group to drill into member details (shows individual member IPs, filter mode, sources, and status). Press Esc to go back.

Note on group members: IGMPv2 uses report suppression, so only one host per group responds per query cycle -- member counts may be understated. IGMPv3 does not suppress reports, so member visibility is much better.

Keyboard shortcuts:

Both tools require NET_RAW capability for raw IGMP sockets.

# Build
docker build -t igmp .

# Run querier daemon
docker run --cap-add=NET_RAW --network=host igmp run --interface eth0

# Run monitor (requires TTY)
docker run -it --cap-add=NET_RAW --network=host igmp /usr/local/bin/igmpmon -I eth0

This library implements:

• Go 1.25+ (built with Go 1.26)
• Linux or macOS (raw sockets)
• Root privileges or CAP_NET_RAW capability

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Run tests: go test -race ./...
4. Commit your changes
5. Push to the branch
6. Open a Pull Request

MIT