If you've noticed your IPv6 address changing frequently—sometimes daily or even more often—you're not experiencing a bug or network problem. This is actually a deliberate privacy feature built into modern IPv6 implementations. Understanding why this happens, when it's beneficial, and how to control it can help you make informed decisions about your network configuration.
Your IPv6 address keeps changing because of Privacy Extensions (also called Temporary Addresses), a standard feature defined in RFC 8981 (previously RFC 4941). This feature is enabled by default on most modern operating systems including Windows (since Vista), macOS, Linux, iOS, and Android. These privacy extensions generate new randomized IPv6 addresses on a regular basis—typically every 24 hours—to prevent tracking and surveillance across the internet.
To understand why addresses change, it's helpful to know how IPv6 addresses are typically constructed. A standard IPv6 address consists of two main parts:
Traditionally, the interface identifier was derived from your device's MAC address using a process called EUI-64. While this made addresses predictable and stable, it created a significant privacy problem: your device could be tracked across different networks using this unique, unchanging identifier.
Privacy Extensions solve the tracking problem by replacing the stable, MAC-based interface identifier with a randomly generated one that changes periodically. Here's how it works:
When Privacy Extensions are enabled, your device maintains two types of addresses simultaneously:
Most operating systems configure temporary addresses with these characteristics:
This means your device generates a fresh temporary address daily, while still accepting traffic on the old address for up to a week to prevent breaking active connections.
The primary benefit of rotating IPv6 addresses is privacy protection:
Without Privacy Extensions, websites and advertisers could track your browsing activity across different sites simply by correlating your unchanging IPv6 address. With temporary addresses that change daily, this correlation window is dramatically reduced.
Static IP addresses enable long-term monitoring of your online activities. Rotating addresses make it much harder for third parties to build comprehensive profiles of your internet usage over extended periods.
If you move between networks (home, work, coffee shop), a static interface identifier would allow tracking your physical movements. Random temporary addresses break this correlation.
While privacy protection is valuable for general internet browsing, there are scenarios where frequently changing IPv6 addresses cause problems:
If you're hosting a web server, game server, or any service that others need to connect to, changing addresses make your service unreachable. DNS records become stale, and users can't find your service.
Setting up remote desktop, SSH access, or VPN connections to your home computer becomes difficult when the address keeps changing. You'd need to constantly update connection settings.
Network administrators often need to create firewall rules based on IP addresses. Constantly changing addresses make granular access control nearly impossible to maintain.
If you've configured port forwarding on your router for gaming, file sharing, or other services, temporary addresses can break these configurations as the address changes.
IT departments often need to correlate network activity with specific devices for troubleshooting or security investigations. Temporary addresses make this correlation more challenging.
While DDNS services work well with changing IPv4 addresses, they can struggle with IPv6 privacy extensions since multiple addresses are active simultaneously.
In addition to Privacy Extensions changing the interface identifier (last 64 bits), many residential ISPs also rotate the network prefix (first 64 bits) assigned to your connection. This typically happens every 24-48 hours, causing your entire IPv6 address range to change. This is a separate issue from Privacy Extensions but compounds the address-changing behavior you might observe.
If you're running servers or services that require stable addresses, you can disable Privacy Extensions. However, this reduces your privacy protection, so only do this when necessary.
Open PowerShell or Command Prompt as Administrator and run:
netsh interface ipv6 set global randomizeidentifiers=disabled
netsh interface ipv6 set privacy state=disabled
To re-enable privacy extensions:
netsh interface ipv6 set global randomizeidentifiers=enabled
netsh interface ipv6 set privacy state=enabled
Edit /etc/sysctl.conf and add or modify these lines:
net.ipv6.conf.all.use_tempaddr = 0
net.ipv6.conf.default.use_tempaddr = 0
Then apply the changes:
sudo sysctl -p
Note: The use_tempaddr values work as follows:
0 = Disabled (use only stable addresses)1 = Enabled (generate temporary addresses but prefer stable)2 = Enabled (generate temporary addresses and prefer them for outgoing connections)For systems using NetworkManager, you can configure privacy extensions per connection:
nmcli connection modify "Connection Name" ipv6.ip6-privacy 0
nmcli connection down "Connection Name"
nmcli connection up "Connection Name"
Replace "Connection Name" with your actual connection name (use nmcli connection show to list connections).
Edit or create /etc/sysctl.conf and add:
net.inet6.ip6.use_tempaddr=0
Then reboot for the changes to take effect, or apply immediately with:
sudo sysctl -w net.inet6.ip6.use_tempaddr=0
For servers and services that require completely stable addresses, configure a static IPv6 address instead of relying on autoconfiguration (SLAAC):
For detailed IPv6 configuration instructions on Windows, see configure IPv6 on Windows. To set a static IPv6 address:
For detailed IPv6 configuration on Linux, see configure IPv6 on Linux. To configure static IPv6 using Netplan, edit /etc/netplan/01-network-manager-all.yaml:
network:
version: 2
ethernets:
eth0:
dhcp4: true
addresses:
- 2001:db8:1234:5678::10/64
routes:
- to: ::/0
via: 2001:db8:1234:5678::1
nameservers:
addresses:
- 2001:4860:4860::8888
- 2001:4860:4860::8844
Apply with: sudo netplan apply
iface eth0 inet6 static
address 2001:db8:1234:5678::10
netmask 64
gateway 2001:db8:1234:5678::1
Here are some guidelines for deciding whether to use Privacy Extensions:
Keep Privacy Extensions Enabled For:
Disable Privacy Extensions For:
Consider Static IPv6 Addresses For:
To see your current IPv6 address and verify whether changes are occurring, you can use online tools like test-ipv6.run. This comprehensive IPv6 connectivity testing tool shows your current IPv6 address, tests your connectivity, and provides detailed information about your IPv6 configuration.
If you're monitoring addresses over time, you might notice multiple IPv6 addresses assigned to a single interface—this is normal with Privacy Extensions. The operating system uses the temporary address for outgoing connections while maintaining stable addresses for incoming connections and deprecated addresses for established sessions.
Your changing IPv6 address is a feature, not a bug. Privacy Extensions represent a thoughtful solution to the tracking and surveillance problems that come with permanent IP addresses. For most users, the default behavior of rotating temporary addresses provides excellent privacy protection with minimal disruption.
However, if you're running services that require stable addresses, understanding how to disable Privacy Extensions or configure static addresses gives you the control you need. The key is making informed decisions based on your specific use case—maximizing privacy for personal devices while ensuring stability for servers and critical services.
Remember that IPv6 privacy is a layered approach: Privacy Extensions handle the interface identifier (last 64 bits), while your ISP may also rotate the network prefix (first 64 bits). Both contribute to address changes, and both serve legitimate purposes in the modern internet architecture.