nat64

A static NAT64 translator written in Rust. Allows IPv6-only hosts to reach IPv4 destinations by translating packets through a TUN device on Linux.

Supports both RFC 6052 prefix-based address synthesis and explicit static 1:1 IPv4:IPv6 mappings.

Install

cargo install nat64

Or from source:

cargo install --path .

TUN device setup

ip tuntap add mode tun nat64
ip link set nat64 up
ip addr add 192.168.255.1/32 dev nat64
ip addr add 2001:db8:1::1/128 dev nat64
ip route add 192.0.2.0/24 dev nat64
ip route add 2001:db8:1:ffff::/96 dev nat64

Configuration

Copy nat64.toml.example to nat64.toml and edit as needed:

tun_device = "nat64"

# NAT64 /96 prefix — IPv4 addresses are embedded in the last 32 bits
prefix = "2001:db8:1:ffff::"

# Local IPv4 address used as source for ICMP errors
ipv4_addr = "192.168.255.1"

# Optional static 1:1 mappings
[[map]]
ipv4 = "192.0.2.10"
ipv6 = "2001:db8:1:4444::10"

Usage

nat64 /etc/nat64.toml

Set the RUST_LOG environment variable to control log verbosity:

RUST_LOG=debug nat64 /etc/nat64.toml

How it works

• IPv4 packets arriving on the TUN device are translated to IPv6 and written back.
• IPv6 packets are translated to IPv4 and written back.
• Without static mappings, destination IPv4 addresses are synthesized into the configured /96 prefix per RFC 6052.
• Static [[map]] entries override prefix-based synthesis for specific addresses.

License

GPL-3.0 — see LICENSE.