Topic: CLAT for access to IPv4 through DNS64 on IPv6 only servers! (Uses Public NAT64) (Read 67816 times)

jaminmc · « **on:** August 08, 2023, 11:25:15 PM »

I wish that the IPv6 servers would provide a private IPv4 address that would route outgoing IPv4 traffic. But I found a solution that uses the free DNS64.org servers, not only for DNS, but free IPv4 routing.
https://nat64.net/public-providers

This does enable IPv6 forwarding for outgoing IPv4 to IPv6 proxy, as my server only got 1 IPv6 address.

So you have a IPv6 only server, and IPv4 only sites won't load, or even worse, you have a program that uses hardcoded IPv4 address in it, and it won't work just using a DNS64 dns server. The following will setup CLAT on your server that will translate IPv4 address to the IPv6 prefix that is detects for the DNS64 IPv6 range.

This was done on Debian 12, but should also work for Ubuntu. After logging in to your server:

Prep for getting system working

Code: [Select]

apt update && apt upgrade
echo "dns-nameserver 2a01:4f8:c2c:123f::1" >> /etc/network/interfaces
echo "dns-nameserver 2a00:1098:2c::1" >> /etc/network/interfaces
apt install resolvconf git build-essential tayga curl
systemctl restart networking

Now we will install CLAT

Code: [Select]

mkdir ~/src
cd ~/src
git clone https://github.com/toreanderson/clatd
make -C clatd install installdeps

This configures CLAT

Code: [Select]

cat <<'EOF' > /etc/clatd.conf
clat-v6-addr=fd00::c1a7
proxynd-enable=false
script-up=nft "add table ip6 clatd" ; nft "add chain ip6 clatd POSTROUTING { type nat hook postrouting priority srcnat; }" ; nft "add rule ip6 clatd POSTROUTING masquerade"
script-down=nft 'delete table ip6 clatd'
EOF
echo "net.ipv6.conf.all.forwarding = 1" >> /etc/sysctl.d/00-ip6fwd.conf
sysctl -p
systemctl restart clatd

Now to test if it works, just run

Code: [Select]

curl 1.1.1.1. You should then see:

Code: [Select]

root@srv[Redacted]:~/src# curl 1.1.1.1
<html>
<head><title>301 Moved Permanently</title></head>
<body>
<center><h1>301 Moved Permanently</h1></center>
<hr><center>cloudflare</center>
</body>
</html>

This uses the DNS from nat64.net. and their servers seem to block pings. So that is why I use `curl 1.1.1.1`.

Edit: fixed so you dont need to reboot.

Forum-Support2 · « **Reply #1 on:** August 09, 2023, 08:52:12 AM »

Hello,

to use IPv4 you need to use an IPv4 address. Other types of services to use IPv4 are not official supported.

melaniewalker · « **Reply #2 on:** August 16, 2023, 03:59:46 AM »

You need to use an IPv4 address.

jaminmc · « **Reply #3 on:** December 04, 2024, 01:26:33 AM »

It has been over a year, and this still works... I am suprised that nobody has pointed out that there was a typo in the `systemctl restart clatd` command. I fixed it

I'm glad I posted the post, as I just created a new server, and I didn't have to figure it out again from scratch.

VS2-free works just fine with this

jaminmc · « **Reply #4 on:** August 30, 2025, 01:06:33 AM »

Quote from: Forum-Support2 on August 09, 2023, 08:52:12 AM

Hello,

to use IPv4 you need to use an IPv4 address. Other types of services to use IPv4 are not official supported.

For Inbound IPv4 traffic, you are correct.

To access the IPv4 internet, servers that do not have IPv6, this works! It uses Public IPv6 to IPv4 gateways.

Author Topic: CLAT for access to IPv4 through DNS64 on IPv6 only servers! (Uses Public NAT64) (Read 67816 times)

jaminmc

CLAT for access to IPv4 through DNS64 on IPv6 only servers! (Uses Public NAT64)

Forum-Support2

Re: CLAT for IPv4 access through DNS64 on IPv6 only servers!

melaniewalker

Re: CLAT for IPv4 access through DNS64 on IPv6 only servers!

jaminmc

Re: CLAT for IPv4 access through DNS64 on IPv6 only servers!

jaminmc

Re: CLAT for IPv4 access through DNS64 on IPv6 only servers!