markzzzsmith:

Supply the following if possible:

• Device problem occurs on

• NETGEAR WNDR3800

• Software versions of OpenWrt/LEDE release, packages, etc.

• OpenWrt 18.06.1 r7258-5eb055306f / LuCI openwrt-18.06 branch (git-18.228.31946-f64b152)

• Steps to reproduce

1. IPv6 enabled by default, OpenWRT automatically generates a unique ULA prefix per RFC4193.

2. ULA prefix is announced with Infinite Preferred and Valid Lifetimes, rather than the RFC4861 defaults:

• AdvPreferredLifetime: Default: 604800 seconds (7 days)

• AdvValidLifetime: Default: 2592000 seconds (30 days)

e.g., using the 'rdisc6' utility to display RAs:

[root@opy mark]# rdisc6 wlp3s0
Soliciting ff02::2 (ff02::2) on wlp3s0...
[...]
Prefix : fdec:91f6:8c3a::/64
On-link : Yes
Autonomous address conf.: Yes
Valid time : infinite (0xffffffff)
Pref. time : infinite (0xffffffff)
[...]

Infinite lifetimes mean these ULA addresses never expire on a host and will always be considered valid source and destination addresses during RFC6724 source and destination address selection.

One consequence is that a mobile device that has a high uptime (e.g. a smartphone), moves between a number of IPv6 networks, and uses IPv6 privacy addresses, could end up with a lot of unusable ULA addresses on its network interface. They may accumulate continuously until the device is rebooted.