Here's some information from a fully updated CentOS 7.6 as of today, unmodified cloud-init 18.2-1.el7.centos.2 but no NetworkManager on AWS with IPV6 enabled.
```
[root@ip-172-31-21-249 ~]# cat /etc/sysconfig/network
# Created by cloud-init on instance boot automatically, do not edit.
#
NETWORKING=yes
NETWORKING_IPV6=yes
IPV6_AUTOCONF=no
[root@ip-172-31-21-249 ~]# ip -6 a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN qlen 1000
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 state UP qlen 1000
inet6 2600:1f14:589:f00:1212:8330:638:9075/64 scope global dynamic
valid_lft 442sec preferred_lft 142sec
inet6 fe80::18:43ff:fe43:693a/64 scope link
valid_lft forever preferred_lft forever
[root@ip-172-31-21-249 ~]# ip -6 route show
unreachable ::/96 dev lo metric 1024 error -113 pref medium
unreachable ::ffff:0.0.0.0/96 dev lo metric 1024 error -113 pref medium
unreachable 2002:a00::/24 dev lo metric 1024 error -113 pref medium
unreachable 2002:7f00::/24 dev lo metric 1024 error -113 pref medium
unreachable 2002:a9fe::/32 dev lo metric 1024 error -113 pref medium
unreachable 2002:ac10::/28 dev lo metric 1024 error -113 pref medium
unreachable 2002:c0a8::/32 dev lo metric 1024 error -113 pref medium
unreachable 2002:e000::/19 dev lo metric 1024 error -113 pref medium
2600:1f14:589:f00::/64 dev ens5 proto kernel metric 256 expires 432sec pref medium
unreachable 3ffe:ffff::/32 dev lo metric 1024 error -113 pref medium
fe80::/64 dev ens5 proto kernel metric 256 mtu 9001 pref medium
```
Thanks for the fast response Ryan!
Here's some information from a fully updated CentOS 7.6 as of today, unmodified cloud-init 18.2-1.el7.centos.2 but no NetworkManager on AWS with IPV6 enabled.
``` 172-31- 21-249 ~]# cat /etc/sysconfig/ network
[root@ip-
# Created by cloud-init on instance boot automatically, do not edit.
#
NETWORKING=yes
NETWORKING_IPV6=yes
IPV6_AUTOCONF=no
[root@ip- 172-31- 21-249 ~]# ps -ef |grep dhc dhclient/ dhclient- -ens5.lease -pf /var/run/ dhclient- ens5.pid -H ip-172-31-21-249 ens5 dhclient/ dhclient6- -ens5.lease -pf /var/run/ dhclient6- ens5.pid ens5 -H ip-172-31-21-249
root 1347 1 0 00:14 ? 00:00:00 /sbin/dhclient -1 -q -lf /var/lib/
root 1425 1 0 00:14 ? 00:00:00 /sbin/dhclient -6 -1 -lf /var/lib/
[root@ip- 172-31- 21-249 ~]# cat /var/lib/ dhclient/ dhclient6- -ens5.lease 000\001$ \263\360\ 355\002\ 030CCi: "; 589:f00: 1212:8330: 638:9075 { -life 150; 24:b3:f0: ed:2:18: 43:43:69: 3a; 2:42:8f: b:a5:8e; 589:f00: 1212:8330: 638:9075 { -life 150; 24:b3:f0: ed:2:18: 43:43:69: 3a; 2:42:8f: b:a5:8e; 589:f00: 1212:8330: 638:9075 { -life 150; 24:b3:f0: ed:2:18: 43:43:69: 3a; 2:42:8f: b:a5:8e; 589:f00: 1212:8330: 638:9075 { -life 150; 24:b3:f0: ed:2:18: 43:43:69: 3a; 2:42:8f: b:a5:8e;
default-duid "\000\001\
lease6 {
interface "ens5";
ia-na "CCi:" {
starts 1562458400;
renew 75;
rebind 120;
iaaddr 2600:1f14:
starts 1562458400;
preferred
max-life 450;
}
}
option dhcp6.client-id 0:1:0:1:
option dhcp6.server-id 0:3:0:1:
}
lease6 {
interface "ens5";
ia-na "CCi:" {
starts 1562458400;
renew 75;
rebind 120;
iaaddr 2600:1f14:
starts 1562458400;
preferred
max-life 450;
}
}
option dhcp6.client-id 0:1:0:1:
option dhcp6.server-id 0:3:0:1:
}
lease6 {
interface "ens5";
ia-na "CCi:" {
starts 1562458477;
renew 75;
rebind 120;
iaaddr 2600:1f14:
starts 1562458477;
preferred
max-life 450;
}
}
option dhcp6.client-id 0:1:0:1:
option dhcp6.server-id 0:3:0:1:
}
lease6 {
interface "ens5";
ia-na "CCi:" {
starts 1562458552;
renew 75;
rebind 120;
iaaddr 2600:1f14:
starts 1562458552;
preferred
max-life 450;
}
}
option dhcp6.client-id 0:1:0:1:
option dhcp6.server-id 0:3:0:1:
}
[root@ip- 172-31- 21-249 ~]# ip -6 a UP,LOWER_ UP> mtu 65536 state UNKNOWN qlen 1000 MULTICAST, UP,LOWER_ UP> mtu 9001 state UP qlen 1000 589:f00: 1212:8330: 638:9075/ 64 scope global dynamic 43ff:fe43: 693a/64 scope link
1: lo: <LOOPBACK,
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens5: <BROADCAST,
inet6 2600:1f14:
valid_lft 442sec preferred_lft 142sec
inet6 fe80::18:
valid_lft forever preferred_lft forever
[root@ip- 172-31- 21-249 ~]# ip -6 route show 589:f00: :/64 dev ens5 proto kernel metric 256 expires 432sec pref medium
unreachable ::/96 dev lo metric 1024 error -113 pref medium
unreachable ::ffff:0.0.0.0/96 dev lo metric 1024 error -113 pref medium
unreachable 2002:a00::/24 dev lo metric 1024 error -113 pref medium
unreachable 2002:7f00::/24 dev lo metric 1024 error -113 pref medium
unreachable 2002:a9fe::/32 dev lo metric 1024 error -113 pref medium
unreachable 2002:ac10::/28 dev lo metric 1024 error -113 pref medium
unreachable 2002:c0a8::/32 dev lo metric 1024 error -113 pref medium
unreachable 2002:e000::/19 dev lo metric 1024 error -113 pref medium
2600:1f14:
unreachable 3ffe:ffff::/32 dev lo metric 1024 error -113 pref medium
fe80::/64 dev ens5 proto kernel metric 256 mtu 9001 pref medium
```
If you ever want to play around with this yourself, I periodically create and publish AMIs based on the template I reference: https:/ /github. com/irvingpop/ packer- chef-highperf- centos7- ami#latest- amis