When working with IPv6, checking your public address isn't as straightforward as IPv4. Many services that work well for IPv4 (like ipinfo.io) may not properly return IPv6 addresses or may prioritize IPv4 responses. This is because:

• Dual-stack networks may prefer IPv4 for compatibility
• Some API endpoints aren't IPv6-enabled
• Network configurations might not route IPv6 traffic properly

Here are several command-line approaches to accurately detect your public IPv6 address:

Method 1: Using Specialized IPv6 Services

curl -6 icanhazip.com
curl -6 ifconfig.co
curl -6 ident.me

Method 2: DNS-Based Query

dig +short AAAA myip.opendns.com @resolver1.opendns.com

Method 3: Network Interface Inspection (Linux)

ip -6 addr show | grep inet6 | grep -v ::1 | grep -v fe80

If you're not getting IPv6 responses:

• Ensure your network supports IPv6 (test with ping6 ipv6.google.com)
• Try forcing IPv6 with the -6 flag in curl
• Check for IPv6 firewalls blocking outbound requests

For scripting purposes, here's a robust solution that falls back to IPv4:

#!/bin/bash
IPV6=$(curl -6 --connect-timeout 5 -s icanhazip.com 2>/dev/null)
if [ -z "$IPV6" ]; then
    IPV4=$(curl -4 --connect-timeout 5 -s icanhazip.com 2>/dev/null)
    echo "Public IPv4: $IPV4"
else
    echo "Public IPv6: $IPV6"
fi

While checking IPv4 addresses is straightforward with services like ipinfo.io, IPv6 detection requires different approaches because:

1. Many ISPs still provide IPv4 by default
2. Some API endpoints don't listen on IPv6
3. Dual-stack configurations may prioritize IPv4

Method 1: Using Dedicated IPv6 Services

The most accurate way is to query IPv6-specific services:

# Linux/Mac
curl -6 ifconfig.co
curl -6 icanhazip.com
curl -6 api64.ipify.org

# Windows PowerShell
(Invoke-WebRequest -Uri "http://ipv6.icanhazip.com" -UseBasicParsing).Content.Trim()

Method 2: Forcing IPv6 Connection

Some services support both protocols but need explicit IPv6 forcing:

curl --ipv6 ipinfo.io/ip
curl -6 https://ident.me

Method 3: Local Interface Inspection

To check all assigned IPv6 addresses on your machine:

# Linux
ip -6 addr show | grep inet6

# MacOS
ifconfig | grep inet6

# Windows
netsh interface ipv6 show addresses

Verify your system actually has IPv6 connectivity:

ping6 ipv6.google.com
traceroute6 example.com

• If commands hang, your ISP might not provide IPv6
• Try different DNS servers (Google's 2001:4860:4860::8888)
• Check firewall rules for ICMPv6 blocking

Here's a bash function to test multiple IPv6 endpoints:

get_ipv6() {
  endpoints=(
    "ifconfig.co" 
    "icanhazip.com"
    "ipv6.ident.me"
    "v6.ident.me"
  )
  
  for endpoint in "${endpoints[@]}"; do
    echo "Testing $endpoint:"
    curl -6 --connect-timeout 3 "https://$endpoint" || echo "Failed"
    echo
  done
}