How to determine secured ipv6 addr and temporary ipv6 addr? Is it secure to use secured ipv6 addr for DDNS and internet aceess?

Question

I'm setting a linux kernel router, how to determine secured ipv6 addr and temporary ipv6 addr?When I run ifconfig on macOS, it will output like this:

inet6 fe80::0000:0000:0000:3e7d%en0 prefixlen 64 secured scopeid 0x8
inet6 2409:0000:0000:0000:0000:0000:0000:ef95 prefixlen 64 autoconf secured   
inet6 2409:0000:0000:0000:0000:0000:0000:8ab8 prefixlen 64 autoconf temporary

But the output on the router is like this:

inet6 addr: 2409:8a50:ae02:4d23:6891:614f:66a1:504b/64 Scope:Global
inet6 addr: 2409:8a50:ae02:4d23:403c:5ee7:98eb:8474/64 Scope:Global
inet6 addr: fe80::403c:5ee7:98eb:8474/10 Scope:Link

Ubuntu 18.04 output:

inet6 2409:8a50:ae2c:2cc0:95c4:27f6:5dba:72cf  prefixlen 64  scopeid 0x0<global>
inet6 2409:8a50:ae2c:2cc0:361:36e3:6d02:314d  prefixlen 64  scopeid 0x0<global>
inet6 fe80::9e5:6b35:11c4:5e7c  prefixlen 64  scopeid 0x20<link>

And I want use a simple script to update DDNS, should I use secured ipv6 addr or temporary ipv6 addr?

Please do not obfuscate IP addresses, provide real ones or use the documentation prefix. I find it exceedingly unlikely that your prefix + generated address would be in 2409::/64. Way too many zeros. — John Mahowald, Sep 30 '19 at 06:34
@JohnMahowald And we have a [reference](https://meta.serverfault.com/q/963) you can point people to. — Michael Hampton, Sep 30 '19 at 08:37

score 1 · Answer 1 · answered Sep 30 '19 at 06:30

In general, avoid temporary addresses in DNS, they change more often. However, pick whatever address you like, such as adding a static address. Should have an entire /64 to use.

Secure in a macOS IPv6 address context means RFC 3972 (Cryptographically Generated Addresses). I do not know enough about the XNU network stack to verify this, but seems plausible.

How to determine secured ipv6 addr and temporary ipv6 addr? Is it secure to use secured ipv6 addr for DDNS and internet aceess?

1 Answers1