On 2019-09-23 18:00, Andrew Kanaber wrote:
When doing static IP configuration, netcfg will reject a gateway
address
outside the host's network as defined by the netmask. This is wrong for
IPv6
because the gateway can legitimately be a link-local address in
fe80::/64
instead of the host's network range. Ubuntu have fixed this bug in
their
version, see LP#1382295
https://bugs.launchpad.net/ubuntu/+source/netcfg/+bug/1382295
The relevant function is netcfg_gateway_reachable in netcfg-common.c
which
simply checks gateway_address & netmask == host_address. It should also
allow
IPv6 addresses in the link local prefix fe80::/64.
Less importantly, the error message it triggers could be a bit clearer,
"The
gateway address you entered is unreachable" sounds like it might be a
network
error when it's purely a user-input parsing rejection - if the code had
actually tried the link-local address it would've worked.
So how does it identify the interface to use in this case? Does the
kernel have special support to pick the correct one if there is only one
non-loopback interface? Generally link-local addresses do need to be
qualified with the interface to be used.
Kind regards
Philipp Kern
