IPv6 Utilities

A Go CLI for IPv6 address analysis, subnet generation, and address translation. Combines and extends several older Python scripts with additional features. A web version of this utility is available at tools.forwardingplane.net.

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Features

• IPv6 Subnet Generation — generate subnets from an IPv6 prefix with optional limit and file output
• IPv4 ↔ RFC 6052 IPv6 Conversion — synthesize and extract IPv4 addresses using NAT64 prefixes
• Custom Prefix Support — non-well-known RFC 6052 prefixes via -k
• SLAAC MAC Decode — extract the original MAC from a non-privacy EUI-64 SLAAC address
• Link-Local ↔ MAC Conversion — bidirectional EUI-64 link-local address conversion
• Reverse DNS Generation — full or partial ip6.arpa names for zone files
• Address Format Display — all representations of an IPv6 address in one shot:
  • Expanded, compressed (RFC 5952), uppercase, URL bracket, dotted nibble, binary
  • Reverse DNS name and address type classification
  • IPv4-in-IPv6 mixed notation for IPv4-mapped addresses (::ffff:x.x.x.x)
  • When a prefix length is supplied: network address, host ID, and network range
  • All valid :: compression permutations

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Installation

Build from source

Requires Go 1.22+. Builds on any platform Go supports.

git clone https://github.com/buraglio/ipv6utils.git
cd ipv6utils
go build -o ipv6utils ipv6utils.go

Move the binary wherever you need it, or reference it via a shell alias.

Makefile targets

make all               # native binary with version embedded
make dist              # all supported platforms → ./dist/
make linux/arm64       # single platform build
make clean             # remove ./dist/ and local binary
make help              # list targets

Override the version string at build time:

make all VERSION=5

Cross-compiled binaries are written to ./dist/ as ipv6utils_OS_ARCH[.exe]. Supported platforms include Linux (x86, ARM, MIPS, RISC-V, s390x, ppc64le), macOS (Intel + Apple Silicon), Windows, FreeBSD, OpenBSD, NetBSD, DragonFly BSD, and Solaris/illumos.

Homebrew (macOS)

brew tap buraglio/ipv6utils
brew install ipv6utils

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Usage

./ipv6utils [OPTIONS]

Flag	Alias	Description
-format ADDR[/N]	-f	Display all format representations of an IPv6 address. Supply a prefix length to also show network range and host ID.
-s ADDR		Convert IPv4↔IPv6 (direction auto-detected). Uses -k prefix.
-m ADDR		Decode MAC address from a SLAAC (EUI-64) IPv6 address.
-local ADDR	-a	Convert link-local ↔ MAC (direction auto-detected).
-ip6.arpa ADDR		Generate a reverse DNS name. Use -n for zone context.
-prefix PREFIX	-p	Base IPv6 prefix for subnet generation. (default: 64:ff9b::)
-new-prefix-length N	-n	New prefix length for subnets or ip6.arpa zone context. (default: 40)
-limit N	-l	Limit subnet output to N entries.
-count	-c	Print only the count of subnets that would be generated.
-output FILE	-o	Save generated subnets to a file.
-k PREFIX		Non-well-known RFC 6052 prefix for synthesis. (default: 64:ff9b::)
-version	-v	Print version and exit.

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Examples

Display all address formats

Without a prefix length — shows representations only:

./ipv6utils -f 2001:db8::1

Expanded:       2001:0db8:0000:0000:0000:0000:0000:0001
Compressed:     2001:db8::1
Uppercase:      2001:DB8::1
URL format:     [2001:db8::1]
Dotted:         2.0.0.1.0.d.b.8.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1
Binary:         0010000000000001:0000110110111000:...
Reverse DNS:    1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.
Address Type:   Documentation (2001:db8::/32)

Compression permutations:
  2001:db8::1
  2001:db8:0::1
  ...

With a prefix length — also shows network address, host ID, and network range:

./ipv6utils -f 2001:db8::1/48

Expanded:       2001:0db8:0000:0000:0000:0000:0000:0001/48
Compressed:     2001:db8::1/48
Uppercase:      2001:DB8::1
URL format:     [2001:db8::1]
Dotted:         2.0.0.1.0.d.b.8...
Binary:         0010000000000001:0000110110111000:...
Reverse DNS:    1.0.0.0...ip6.arpa.
Address Type:   Documentation (2001:db8::/32)

Network:        2001:0db8:0000:0000:0000:0000:0000:0000/48
Host ID:        ::1/48
Network range:  2001:0db8:0000:0000:0000:0000:0000:0000 -
                2001:0db8:0000:ffff:ffff:ffff:ffff:ffff

Compression permutations:
  2001:db8::1
  ...

IPv4-mapped addresses include a mixed-notation line:

./ipv6utils -f ::ffff:192.0.2.1

Expanded:       0000:0000:0000:0000:0000:ffff:c000:0201
Compressed:     192.0.2.1
...
Address Type:   IPv4-Mapped (::ffff:0:0/96)
IPv4-in-IPv6:   ::ffff:192.0.2.1

IPv4 → Synthesized IPv6

./ipv6utils -s 8.8.8.8

Converted IPv4 to synthesized IPv6: 64:ff9b::808:808

Synthesized IPv6 → IPv4

./ipv6utils -s 64:ff9b::808:808

Converted synthesized IPv6 to IPv4: 8.8.8.8

Link-local ↔ MAC

./ipv6utils -local 00:11:22:33:44:55

Link-local address: fe80::0211:22ff:fe33:4455

./ipv6utils -local fe80::0211:22ff:fe33:4455

MAC from link-local: 00:11:22:33:44:55

Decode MAC from SLAAC address

./ipv6utils -m 3fff:0::0200:5eff:fe00:5325

Decoded MAC address: 00:00:5e:00:53:25

Generate subnets

./ipv6utils -p 3fff::/32 -n 40 -l 5

Generating 256 prefixes...
3fff::/40
3fff:0:100::/40
3fff:0:200::/40
3fff:0:300::/40
3fff:0:400::/40

Count only:

./ipv6utils -p 3fff::/32 -n 40 -c

Number of prefixes: 256

Save to file:

./ipv6utils -p 3fff::/32 -n 40 -o subnets.txt

Reverse DNS names

Full ip6.arpa name (-n 0):

./ipv6utils -ip6.arpa 2001:db8:abcd::0211:22ff:fe33:4455 -n 0

5.5.4.4.3.3.e.f.f.f.2.2.1.1.2.0.0.0.0.0.d.c.b.a.8.b.d.0.1.0.0.2.ip6.arpa.

Partial name for a /56 zone file:

./ipv6utils -ip6.arpa 2001:db8:abcd::0211:22ff:fe33:4455 -n 56

5.5.4.4.3.3.e.f.f.f.2.2.1.1.2.0.0.0

Version

./ipv6utils -v

ipv6utils 4