** Description changed: My network has both DHCPv6 and SLAAC for IPv6. From both a privacy perspective and readability reasons, DHCPv6 should *always* be preferred over SLAAC addresses when available. NetworkManager has always been able to adhere to that by simply setting ip6.privacy=0 for the connection. So if you would - for instance - run `curl ifconfig.co`, the DHCPv6 address would be used to connect to the outside world. Since the update to 1.36.6, this is no longer the case. NetworkManager now routes outgoing traffic through the SLAAC address, even if ip6.privacy=0 is set for the connection. Setting net.ipv6.conf.all.use_tempaddr=0 and net.ipv6.conf.<interface>.use_tempaddr=0 with sysctl also no longer has any effect. Removing the SLAAC addresses with `ip addr del` or disabling SLAAC RA's altogether is the only way to stop NetworkManager from preferring SLAAC over DHCPv6 now. Looking at the changelog of NetworkManager 1.36.6, things regarding IP address order and temporary addresses have been changed in that release: https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/blob/nm-1-36/NEWS When running `ip -6 a`, the list now sorts SLAAC addresses above DHCPv6 addresses. With NetworkManager 1.36.4 this was not the case. (The Linux kernel uses the address highest in the list as preferred.) This can break many real-life use cases. For instance, my router gives out static leases to my machines. Those addresses are whitelisted in all kinds of firewalls to allow me to access servers for my work. Now that the "wrong" address is being preferred for outgoing traffic (a SLAAC address that I have no influence on), I am being locked out of the servers in question unless I forcefully remove the addresses or disable SLAAC on my router, so my outgoing traffic is being routed through the DHCPv6 address again. - So this update introduces a very breaking change to an LTS release, - while LTS releases should be stable. + So this update introduces a very breaking change in IPv6 source address + selection to an LTS release, while LTS releases should be stable. I should note that the bug is not present in NetworkManager 1.38.0 on Debian sid. That just prefers DHCPv6 addresses when available, like it should. /etc/os-release: PRETTY_NAME="Ubuntu 22.04 LTS" NAME="Ubuntu" VERSION_ID="22.04" VERSION="22.04 LTS (Jammy Jellyfish)" VERSION_CODENAME=jammy ID=ubuntu ID_LIKE=debian HOME_URL="https://www.ubuntu.com/"; SUPPORT_URL="https://help.ubuntu.com/"; BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"; PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"; UBUNTU_CODENAME=jammy nmcli -v: nmcli tool, version 1.36.6
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1977619 Title: NetworkManager 1.36.6 orders IPv6 addresses incorrectly To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1977619/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
