Introduction

IPv6 adoption continues to grow, and for operators running proxy services like V2Ray, enabling native IPv6 support can improve performance, reduce middleboxes’ interference, and future-proof infrastructure. This guide provides a practical, technical walkthrough to configure IPv6 for V2Ray on a Linux server, covering system-level setup, V2Ray configuration snippets, firewall and reverse proxy considerations, DNS, testing, and troubleshooting. The instructions target site operators, enterprise users, and developers who need a reliable dual-stack or IPv6-only deployment.

Prerequisites and high-level considerations

Before making changes, ensure you have:

  • Root or sudo access to the server.
  • An IPv6-capable hosting provider that assigns a public /64 or routable IPv6 address.
  • V2Ray core installed (v4.23+ recommended for best feature support).
  • If using a reverse proxy, Nginx (1.13+ recommended) or similar compiled with IPv6 support.
  • A domain name with the ability to add AAAA DNS records (and TLS certificate support via Let’s Encrypt or other CA).

Enable IPv6 forwarding and kernel settings

On Linux servers, enabling IPv6 forwarding is a mandatory first step for routing traffic. Persist the setting via sysctl:

Command: edit /etc/sysctl.conf or drop a file under /etc/sysctl.d/ and add:

net.ipv6.conf.all.forwarding=1

Then apply immediately with sysctl -p or sysctl –system. If you rely on RA/SLAAC settings, ensure interfaces are properly configured by your provider (static or SLAAC). Verify with ip -6 addr and ip -6 route.

Firewall and packet filtering for IPv6

IPv6 uses separate tables from IPv4. If you use ip6tables or nftables, allow your V2Ray service port(s) and established traffic. Example ip6tables rules:

Allow loopback and established:

ip6tables -A INPUT -i lo -j ACCEPT

ip6tables -A INPUT -m conntrack –ctstate ESTABLISHED,RELATED -j ACCEPT

Allow V2Ray port (example 443) over IPv6:

ip6tables -A INPUT -p tcp –dport 443 -j ACCEPT

For nftables, ensure you have inet family tables and allow the same ports. If your server runs firewalld, use IPv6-aware commands: firewall-cmd –permanent –add-port=443/tcp –zone=public and reload.

Note: if you plan IPv6-only V2Ray with NAT64 or proxying, consider allowing ICMPv6 types required for path MTU discovery (e.g., 128-130).

DNS: AAAA records and reverse DNS

To enable clients to connect via IPv6 addresses, add an AAAA record in your DNS for the domain pointing to the server’s IPv6 address. For dual-stack domains, keep both A and AAAA records. Example:

v2.example.com. IN AAAA 2001:db8:abcd::1

If your hosting provider supports PTR records, set a reverse DNS for the IPv6 address to improve reputation for TLS issuance and reverse lookups.

Obtaining TLS certificates on IPv6

Most ACME clients (certbot) support IPv6 validation as long as the AAAA record exists and the server listens on IPv6 port 80/443 for the challenge. Example certbot command:

certbot certonly –webroot -w /var/www/html -d v2.example.com

If you run Nginx, configure it to listen on IPv6 during validation: listen [::]:80; and ensure firewall allows inbound IPv6 traffic on 80/443.

V2Ray server configuration for IPv6

V2Ray core reads JSON configuration files. To bind to IPv6, use the wildcard IPv6 address together with the correct port. Important items:

  • listen address: use “::” or the specific IPv6 address like “2001:db8::1”.
  • domainStrategy: to prefer IPv6 resolution for outbound domains, set “domainStrategy”: “UseIPv6”.
  • sockopt: options like “tcpFastOpen”: true can be used to reduce latency on supported kernels.

Example inbound snippet for a WebSocket+TLS (VLESS or VMess) listener on IPv6:

“inbounds”: [{ “port”: 443, “listen”: “::”, “protocol”: “vless”, “settings”: { “clients”:[{ “id”:”YOUR-UUID”, “flow”:”” }] }, “streamSettings”: { “network”: “ws”, “security”: “tls”, “tlsSettings”: { “certificates”: [{ “certificateFile”: “/etc/letsencrypt/live/v2.example.com/fullchain.pem”, “keyFile”: “/etc/letsencrypt/live/v2.example.com/privkey.pem” }] }, “wsSettings”: { “path”: “/v2” } } }]

For an IPv6-only server you might restrict listening to the IPv6 interface and omit IPv4 entirely by not binding to 0.0.0.0.

Outbound configuration and domain resolution

To ensure V2Ray outbound connections attempt IPv6 first, set:

“outbound”: { “protocol”: “freedom”, “settings”: {}, “streamSettings”: {}, “tag”: “direct” }, “routing”: { “domainStrategy”: “UseIPv6” }

This setting instructs V2Ray’s DNS/resolution logic to favor AAAA records. Note that upstream servers or clusters must support IPv6; otherwise, connections will fall back to IPv4 if both are available.

Reverse proxy (Nginx) configuration with IPv6

If you use Nginx to handle TLS and then proxy to V2Ray’s local port, ensure Nginx listens on IPv6. Example server block for WebSocket passthrough:

server { listen 443 ssl; listen [::]:443 ssl; server_name v2.example.com; ssl_certificate /etc/letsencrypt/live/v2.example.com/fullchain.pem; ssl_certificate_key /etc/letsencrypt/live/v2.example.com/privkey.pem; location /v2 { proxy_redirect off; proxy_pass http://127.0.0.1:10000; proxy_http_version 1.1; proxy_set_header Upgrade $http_upgrade; proxy_set_header Connection “upgrade”; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; } }

Note the explicit listen [::]:443 line to accept IPv6 connections. If proxy_pass uses localhost, keep the V2Ray inbound listening on 127.0.0.1 or a local IPv4 port; else, you may proxy to a local IPv6 address such as [::1]:10000.

Client configuration tips for IPv6 connectivity

Client-side settings are straightforward: the client must resolve the domain to an AAAA record or use the IPv6 address directly. For domain-based clients, ensure DNS lookup returns AAAA. On mobile or desktop clients that may prefer IPv4, set the client to use the domain forcibly or configure the client to prefer IPv6 if supported.

Example client host field: v2.example.com or explicitly [2001:db8::1] (some clients require brackets for literal IPv6 addresses).

Testing and verification

Use these commands to verify IPv6 functionality:

  • ip -6 addr — confirm the interface has an IPv6 address.
  • ip -6 route — check default IPv6 route.
  • curl -6 -v https://v2.example.com/ — test IPv6 TLS connectivity to the domain.
  • curl -g “http://[2001:db8::1]:port/” — direct IPv6 test against an address.
  • ping6 v2.example.com and traceroute6 v2.example.com — network path diagnostics.
  • Use client logs (V2Ray service logs) for handshake and routing details.

On the server, check V2Ray logs for inbound connections and confirm the source addresses are IPv6. If using Nginx, check its access logs to see IPv6 client addresses as well.

Troubleshooting common issues

Here are frequent pitfalls and remedies:

  • No AAAA record: Add the AAAA DNS entry and wait for propagation. Some resolvers cache negative answers—flush DNS caches where possible.
  • IPv6 firewall blocking: Double-check ip6tables or nftables rules. Temporary test: allow all IPv6 inbound (not recommended long-term) to isolate the problem.
  • ACME validation fails over IPv6: Ensure port 80/443 are reachable on IPv6 and that your webroot or challenge is properly served for the domain’s AAAA record.
  • Client connects via IPv4 despite AAAA existing: The client or local resolver might prefer IPv4. Force AAAA lookup or adjust client settings.
  • Path MTU / fragmentation issues: Permit ICMPv6 type 2 (Packet Too Big) and avoid blocking essential ICMPv6 types.

Operational and security recommendations

For production environments:

  • Use TLS termination (certs stored securely) and strong TLS profiles (TLS 1.2/1.3, modern ciphers).
  • Keep V2Ray and system packages updated. Enable automatic updates or a patching schedule.
  • Limit exposed ports to the minimum required and use rate limiting or connection limits at the firewall layer.
  • Log minimally required information to respect privacy but retain enough for debugging and security analysis.
  • Regularly test failover between IPv4 and IPv6 for resilience in dual-stack setups.

Conclusion

Enabling IPv6 for V2Ray requires coordinated changes at the kernel, firewall, DNS, reverse proxy, and application configuration layers. By binding V2Ray to IPv6 addresses, adding AAAA DNS records, ensuring firewall rules allow IPv6 traffic, and testing thoroughly, you can achieve a fast and reliable IPv6-capable proxy service. For detailed deployments, tailor the configuration snippets above to your environment and document the steps in your operational runbooks.

For more guides and managed solutions that help deploy secure, dual-stack proxy infrastructures, visit Dedicated-IP-VPN at https://dedicated-ip-vpn.com/.