I have been fiddling with IPv6 and address lifetimes. I found out that the
valid_lft attribute will make a v6-address disappear automagically, if used correctly. To extend an address' lifetime I would
ip addr change 1:2:3:4::1/112 dev eth0 valid_lft 86000
The use of
ip addr change does not appear in any man-page I have access to (Debian,Ubuntu, and online) and also not in the official documentation. I found it in an article referring to an email from 2009 to the ipv6-ops mailing-list.
From what I could determine playing around, I guess one can always use
ip addr change instead of
ip addr add, because if an address does not exist,
ip will add one, just if
ip addr add was used.
Is that correct, i.e., can anybody explain what precisely
ip addr change does and how it differs from
ip addr add?