What are common IPv6 troubleshooting steps?

Common IPv6 troubleshooting steps include:

1. Check Interface Configuration:

   • Use ip -6 addr show to verify that the IPv6 address is correctly assigned to the interface.

2. Verify Link-Local Address:

   • Ensure that the link-local address (starting with fe80::) is present and correctly configured, as it is essential for local communication.

3. Check Connectivity:

   • Use ping6 to test connectivity to a known IPv6 address, such as a link-local address of another device on the same network or a global address.

4. Examine Routing:

   • Use ip -6 route show to check the routing table and ensure that there are valid routes for the IPv6 addresses you are trying to reach.

5. Check Neighbor Discovery:

   • Use ip -6 neigh show to view the neighbor cache and ensure that the device can resolve the link-layer addresses of neighboring devices.

6. Inspect Firewall Rules:

   • Verify that firewall rules are not blocking IPv6 traffic. Use iptables -L or nft list ruleset to check for any rules affecting IPv6.

7. Review DNS Configuration:

   • Ensure that DNS is correctly configured for IPv6. Use dig AAAA <hostname> to check if the hostname resolves to an IPv6 address.

8. Check DHCPv6 or SLAAC:

   • If using DHCPv6, ensure that the DHCP server is functioning correctly. For SLAAC, verify that Router Advertisements (RAs) are being received.

9. Examine Logs:

   • Check system logs (e.g., /var/log/syslog or journalctl) for any error messages related to networking or IPv6.

10. Use Traceroute:

    • Use traceroute6 to trace the path to an IPv6 address and identify where packets may be getting dropped.

By following these steps, you can systematically identify and resolve common IPv6 connectivity issues.