Userland NAT64 implementation on Linux in Ruby.

• Stateless NAT64 - RFC 7915
  • Maps 1 IPv6 Address : 1 IPv4 Address
  • Combine with kernel netfilter NAT66 masquerade to archieve stateful NAT64 NAPT functionality (multiple IPv6 address/port : 1 IPv4 Address)
  • IPv6(src=nat66outer, dst=pref64n+ipv4) -> IPv4(src=ipv4nat64outer, dst=ipv4)
  • IPv4(src=ipv4, dst=ipv4nat64outer) -> IPv6(src=pref64n+ipv4, dst=nat66outer)

# Gemfile
source 'https://rubygems.org'
gem 'xlat'

TODO: Write usage instructions here

• Expecting no difference in IPv4 and IPv6 MTU
• If an IPv4 packet is translated into an IPv6 packet larger than MTU, the packet is silently discarded.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Requires: iproute2, trafgen&ifpps from netsniff-ng (v0.6.8 of netsniff-ng has a bug and you need to build the development version).

The benchmark/ directory has trafgen scenarios to generate artificial traffic to benchmark Xlat.

sudo XLAT_PROFILE=1 XLAT_NOJIT=1 ruby ./benchmark/run.rb ./benchmark/tcp.cfg
# or if your ruby is managed by rbenv
sudo XLAT_PROFILE=1 XLAT_NOJIT=1 "$(rbenv which ruby)" ./benchmark/run.rb ./benchmark/tcp.cfg

If XLAT_PROFILE variable is set, profile is emitted every 10 seconds at /tmp/xlat-#{pid}.pf2profile. You need to disable YJIT by setting XLAT_NOJIT variable due to the current limitation of Pf2.

Requires: Docker, containerlab, iproute2, iperf3.

cd clab/
./build
containerlab deploy --reconfigure
sudo ip netns exec clab-464xlat-ue-pd-sv iperf3 -s

# in another session:
sudo ip netns exec clab-464xlat-ue-pd-ue iperf3 -c 64:ff9b::192.0.2.80
docker kill --signal=USR1 clab-464xlat-ue-pd-plat
docker cp clab-464xlat-ue-pd-plat:/tmp/xlat-1.pf2profile .
pf2 report ./xlat-1.pf2profile -o ./xlat.json

Requires: CRuby built with clang compiler.

fuzz/run performs fuzzing against the parsers and Xlat::Rfc7915 translator.

./fuzz/run

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/xlat.

The gem is available as open source under the terms of the MIT License.

• Copyright (c) 2024 Sorah Fukumori
• Copyright (c) 2024-2025 Kasumi Hanazuki
• Copyright (c) 2022 Kazuho Oku
  • Some part of this source code are based on the source code at https://github.com/kazuho/rat available under MIT License