dhcpcd create IPv6 network route using gateway address instance of link# one on FreeBSD #506
Description
When dhcpcd uses SLAAC for address configuration, it add a IPv6 route entry like this:
Internet6:
Destination Gateway Flags Netif Expire
2001:xxxx:xxxx:xxxx::/64 fe80::1%igb0 UG igb0
2001:xxxx:xxxx:xxxx::2 link#5 UHS lo0
Instance of something like this:
Internet6:
Destination Gateway Flags Netif Expire
2001:xxxx:xxxx:xxxx::/64 link#1 U igb0
2001:xxxx:xxxx:xxxx::2 link#5 UHS lo0
This network route entry creates issues on connections with hosts in same network becauses that causes than the router (fe80::1%igb0) sends ICMPv6 Redirect packets for reconfigure routing between hosts, and it can cause connection loss if host not allow ICMPv6 Redirect packets.
dhcpcd logs has something similar to:
May 19 20:33:01 host dhcpcd[22861]: dhcpcd-10.2.2 starting
May 19 20:33:01 host dhcpcd[23507]: DUID 00:01:00:01:ff:ff:ff:ff:ff:ff:ff:ff:ff:ff
May 19 20:33:01 host dhcpcd[23507]: igb0: IAID ee:ee:ee:ee
May 19 20:33:02 host dhcpcd[23507]: igb0: soliciting an IPv6 router
May 19 20:33:02 host dhcpcd[23507]: igb0: Router Advertisement from fe80::1
May 19 20:33:02 host dhcpcd[23507]: igb0: adding address 2001:xxxx:xxxx:xxxx::2/64
May 19 20:33:02 host dhcpcd[23507]: igb0: adding temporary address 2806:xxxx:xxxx:xxxx:1111:2222:3333:4444/64
May 19 20:33:02 host dhcpcd[23507]: igb0: adding route to 2001:xxxx:xxxx:xxxx::/64 via fe80::1
May 19 20:33:59 host dhcpcd[23507]: igb0: adding temporary address 2001:xxxx:xxxx:xxxx:5555:6666:7777:8888/64
Also dhcpcd adds a secondary temporary address some seconds or few minutes after the service start