Unlike other systems, Fedora 25 workstation doesn't use stable IPv6 addresses, by default.For example, with CentOS 7 or Fedora 23, a stable IPv6 is automatically configured (in an IPv6 enabled network where a IPv6 router is present) - i.e. one that is derived from the MAC-address.That IPv6 address then can be used in an DNS AAAA-record.In contrast to that, the IPv6 address of a Fedora 25 workstation system doesn't have any relation to its MAC address and doesn't seem to be stable.How to configure deterministic and stable IPv6 addresses on Fedora 25?
Stable IPv6 address on Fedora
fedora;ipv6
On Fedora 25 Workstation, NetworkManager (NM) configures all network interfaces, by default. That means also the wired ones. And the NetworkManager doesn't create EUI-64 derived IPv6 addresses. Instead it generates so called 'stable-privacy' ones. Apparently to not disclose the MAC address to each IPv6 destination.This can be changed for a given interface $i via changing the IPV6_ADDR_GEN_MODE key in the /etc/sysconfig/network-scripts/ifcfg-$i configuration file. For example via:sed -i 's/^IPV6_ADDR_GEN_MODE=stable-privacy/IPV6_ADDR_GEN_MODE=eui64/' \  /etc/sysconfig/network-scripts/ifcfg-$iThe change is effective after NetworkManager rereads its configuration and after a reconnect:nmcli con reloadnmcli con down $inmcli con up $iNotesthis option isn't exposed via the NM settings GUIthe interface configuration files under /etc/sysconfig/network-scripts read by NM are Fedora/Redhat specific, but the configuration key is not - i.e. on other distributions NM just reads the interface configurations from different locations/configuration files