MMDBridge

MMDBridge is a schema-driven CSV <-> MMDB bridge for custom IP intelligence datasets. It converts flat tables of IP/CIDR ranges into typed MaxMind DB files, and exports MMDB contents back into stable CSV for review, diffing, enrichment, and database import workflows.

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Overview

Security, fraud, network, and infrastructure teams often keep IP intelligence in CSV exports, warehouse tables, spreadsheet workflows, or internal control planes. Production systems usually want a compact lookup database with stable runtime semantics.

MMDBridge provides the bridge between those layers:

CSV / table export + YAML schema -> typed MMDB
typed MMDB + YAML schema -> diff-friendly CSV

The schema is the contract. It defines the network column, field types, nested MMDB paths, array splitting, required fields, and MMDB metadata. Builds are reproducible by default and do not depend on external feeds.

System Behavior

MMDBridge reads a CSV with one IP address or CIDR prefix per row, converts configured columns into MaxMind DB data types, assembles nested records from dotted paths, and writes a MaxMind DB file using the official Go writer.

The reverse path walks all networks in an MMDB, extracts fields declared by the same schema, and writes a deterministic CSV projection suitable for code review, audit logs, regression tests, and downstream data pipelines.

flowchart LR
A["CSV with IP/CIDR rows"] --> B["Schema parser"]
B --> C["Typed record builder"]
C --> D["MMDB writer"]
D --> E["Custom MMDB"]
E --> F["MMDB network iterator"]
B --> G["CSV projection"]
F --> G

Loading

Features

Area	Capability
Typed conversion	string, bool, int32, uint16, uint32, uint64, float32, float64, string_array
Nested records	Map flat CSV columns to paths such as geo.country.iso_code
Bidirectional workflow	Build MMDB from CSV and export MMDB back to CSV
Deterministic metadata	Fixed build_epoch support for reproducible artifacts
IPv4 / IPv6	Build IPv4-only or mixed IPv4/IPv6 databases
Array fields	Split CSV cells into string arrays with a configured delimiter
Operational fit	Works in CI, release jobs, data pipelines, and local review workflows

Quick Start

git clone https://github.com/ipanalytics/mmdbbridge.git
cd mmdbbridge
go test ./...
go build -o mmdbbridge ./cmd/mmdbbridge
./mmdbbridge build \
--schema examples/custom-intel.yaml \
--csv examples/custom-intel.csv \
--out custom-intel.mmdb
./mmdbbridge export \
--schema examples/custom-intel.yaml \
--mmdb custom-intel.mmdb \
--out exported.csv

Installation

From Go

go install github.com/ipanalytics/mmdbbridge/cmd/mmdbbridge@latest

From Source

git clone https://github.com/ipanalytics/mmdbbridge.git
cd mmdbbridge
go test ./...
go build -o mmdbbridge ./cmd/mmdbbridge

Usage

Build An MMDB

mmdbbridge build \
--schema examples/custom-intel.yaml \
--csv examples/custom-intel.csv \
--out custom-intel.mmdb

Input CSV:

cidr,asn,is_vpn,country,tags203.0.113.0/24,64500,true,US,vpn|hosting2001:db8:42::/48,64501,false,DE,enterprise|office

Schema:

network:
column: cidrmetadata:
database_type: custom-ip-inteldescription: Custom IP intelligence datasetip_version: 6record_size: 28build_epoch: 1include_reserved_networks: truefields:
asn:
column: asntype: uint32is_vpn:
column: is_vpntype: boolgeo.country.iso_code:
column: countrytype: stringtags:
column: tagstype: string_arraysplit: "|"

Record produced for 203.0.113.1:

{
"asn": 64500,
"is_vpn": true,
"geo": {
"country": {
"iso_code": "US"
}
},
"tags": ["vpn", "hosting"]
}

Export An MMDB

mmdbbridge export \
--schema examples/custom-intel.yaml \
--mmdb custom-intel.mmdb \
--out exported.csv

Output CSV:

cidr,asn,country,is_vpn,tags2001:db8:42::/48,64501,DE,false,enterprise|office203.0.113.0/24,64500,US,true,vpn|hosting

Generate A Schema Template

mmdbbridge schema --out schema.yaml

Commands

Command	Purpose
mmdbbridge build --schema schema.yaml --csv input.csv --out output.mmdb	Compile a CSV into an MMDB
mmdbbridge export --schema schema.yaml --mmdb input.mmdb --out output.csv	Export an MMDB projection to CSV
mmdbbridge schema --out schema.yaml	Write a starter schema

Data Format

Network Column

network.column names the CSV column containing an IP address or CIDR prefix.

network:
column: cidr

Host addresses are normalized to /32 for IPv4 and /128 for IPv6. CIDR prefixes are canonicalized before insertion.

Metadata

Key	Description
database_type	MMDB database type string
description	English metadata description
ip_version	4 or 6; use 6 for mixed IPv4/IPv6 data
record_size	MMDB record size: 24, 28, or 32
build_epoch	Unix timestamp embedded in metadata
include_reserved_networks	Allows documentation, private, and reserved ranges

Fields

Each entry under fields maps an MMDB path to a CSV column and explicit type.

fields:
risk.score:
column: risk_scoretype: uint16required: truelabels:
column: labelstype: string_arraysplit: "|"

Supported types:

Type	Notes
string	UTF-8 string value
bool	Parsed with Go boolean semantics
int32	Signed 32-bit integer
uint16	Unsigned 16-bit integer
uint32	Unsigned 32-bit integer
uint64	Unsigned 64-bit integer
float32	32-bit floating point
float64	64-bit floating point
string_array	Delimited string list

Outputs And Artifacts

Artifact	Producer	Consumer
.mmdb	build	Runtime lookup services, API gateways, enrichment jobs
.csv	export	Review tools, Git diffs, warehouses, spreadsheets
.yaml	schema	CI jobs, data pipelines, release processes

MMDB output is suitable for standard MaxMind DB readers. CSV output is stable enough for pull request review and downstream ingestion, provided the schema is kept under version control.

Operational Notes

• Keep schemas versioned with the datasets they describe.
• Use a fixed metadata.build_epoch for byte-stable release artifacts.
• Prefer explicit columns over type inference in production pipelines.
• Run mmdbbridge export in CI when reviewing generated MMDB changes.
• Store source CSVs or upstream extract jobs separately from generated MMDB artifacts.

CI example

name: mmdbbridgeon:
pull_request:
paths:
- "data/**"
- "schemas/**"jobs:
build-mmdb:
runs-on: ubuntu-lateststeps:
- uses: actions/checkout@v4
- uses: actions/setup-go@v5with:
go-version: "1.22"
- run: go install github.com/ipanalytics/mmdbbridge/cmd/mmdbbridge@latest
- run: | mmdbbridge build \ --schema schemas/ip-intel.yaml \ --csv data/ip-intel.csv \ --out dist/ip-intel.mmdb

Project Scope

MMDBridge focuses on schema-governed conversion between tabular IP datasets and MMDB files.

In scope:

• CSV input and output.
• YAML schemas.
• Typed MMDB record construction.
• Nested map construction from dotted field paths.
• Deterministic build metadata.
• Local, CI, and data-pipeline execution.

Planned work:

• configurable overlap policy for conflicting networks;
• merge/enrichment mode against a base MMDB;
• schema validation output designed for CI annotations;
• Parquet input and export.

Use Cases

Team	Example
Security engineering	Build private VPN, proxy, scanner, or abuse intelligence databases
Fraud and risk	Ship custom IP risk attributes to low-latency lookup services
Network operations	Convert allocation, ASN, region, or routing metadata into MMDB
Data engineering	Round-trip MMDB datasets through CSV review and warehouse jobs
Research	Create reproducible MMDB artifacts from published or internal measurements

Limitations

• CSV is the supported tabular format in the current implementation.
• Overlapping networks currently use the writer's default replacement behavior.
• Export projects fields declared in the schema; undeclared MMDB fields are not emitted.
• The tool does not bundle third-party IP intelligence feeds.

Directory Structure

.
├── cmd/mmdbbridge/ # CLI entrypoint
├── examples/ # Example schema and CSV input
├── internal/bridge/ # CSV/MMDB build and export logic
├── internal/schema/ # YAML schema model and validation
├── site/ # README and project visual assets
├── go.mod
└── README.md

Deployment

MMDBridge is distributed as a single Go binary. It has no runtime service dependency and fits common release patterns:

Environment	Pattern
Local workstation	Build and inspect custom datasets before committing
CI	Compile MMDB artifacts from reviewed CSV/schema inputs
Release job	Publish .mmdb files as versioned build artifacts
Data pipeline	Convert scheduled table exports into runtime lookup databases
Container image	Package the binary with schemas and source datasets for repeatable builds

Minimal container build:

FROM golang:1.22 AS build
WORKDIR /src
COPY . .
RUN go build -o /out/mmdbbridge ./cmd/mmdbbridge
FROM gcr.io/distroless/base-debian12
COPY --from=build /out/mmdbbridge /usr/local/bin/mmdbbridge
ENTRYPOINT ["/usr/local/bin/mmdbbridge"]

Documentation

• Example schema: examples/custom-intel.yaml
• Example CSV: examples/custom-intel.csv
• MaxMind DB format: maxmind/MaxMind-DB
• Go writer library: maxmind/mmdbwriter

License

Apache License 2.0. See LICENSE.

Disclaimer

MMDBridge is infrastructure tooling for user-provided datasets. Validate source data, schema changes, and generated artifacts before using them in production decision paths.