WAN Interface as DHCP client error

[the other]

Hey everyone,
I've got a question:
at home the set up is this

• router with IPv4 und 6 as dualstack, behind that first router sits pfsense

• IPv4 is working, IPv6 is working, I reach various IPv6 test sites, I reach clients in my LAN with v6 and v4...

• on PFsense WAN IF is setup as DHCP6 Client, other Interfaces are tracking wan. All get a global unique adress, I do not use DHCPv6 server but slaac, which works fine as well

BUT: about once an hour I get this error notification:
dhcp6c 83522 unknown or unexpected DHCP6 option opt_86, len 16

The process starts with the entry:
May 29 16:46:09 dhcp6c 83522 Sending Renew

then
May 29 16:46:09 dhcp6c 83522 unknown or unexpected DHCP6 option opt_86, len 16

then
May 29 16:46:09 dhcp6c 83522 dhcp6c Received INFO

I don't get it, what is this option? Why is everything seemingly working as expected but notifiying about this error??
What to do?
If you need more information please gimme a hint...thank you!!

[johnpoz]

@the-other said in WAN Interface as DHCP client error:

opt_86

This is dhcp option for a PCP server.

https://www.rfc-editor.org/rfc/rfc7291.html

If client didn't ask for an option, and gets sent one - it could log that.. If everything is working, it amounts to log spam..

[the other]

@johnpoz
Hey,
thank you for answering this issue for me!!
It took me the whole Saturday to find an answer...stumbled over the PCP note but could not really understand, why this should be bothering ME for there is no PCP...
So at last I know that I spent half of my weekend with spam... Ha!

Thanx for your help, I will ignore that message then...!!

[johnpoz]

@the-other your isp prob handing that out for its own hardware, if you replaced their hardware with pfsense, pfsense wouldn't ask for that. So to its unknown - and logging that.

PCP is another way of opening up ports on a nat, are you getting a global public IP or a cgnat IP? PCP is like an alternative to nat-pmp, also used for learning nat64 prefixes, etc.. It can have many uses.

My "guess" would be something your isp uses with their own devices - but since I take it your not using their device pfsense doesn't ask doesn't want to hear about those servers.

As long as everything is working how you want, yeah it amounts to log spam. I not sure how set the dhcp client to not log that - might be possible with some of the advanced options you can set on the dhcp client on your wan interface.

[the other]

@johnpoz
Thank you again for explaining!
I have a German Telekom VDSL with true dualstack, get a dynamic public IPv4 (and v6) from that ISP.
I get an /56 prefix. The first router is a fritzbox, pfsense is set as exposed host for IPv6 and (as mentioned) gets the GUA for WAN by dhcp from fritzbox. It cuts a /59 net out of the ISP's /56 (fritzbox uses two /64 for LAN and Guest-LAN) as described in this forum a few times by others)...

Since everything intern and (trusting those various IPv6 test sites) extern seems to work just fine (intern working with track interface, slaac, no active dhcpv6 servers) I put the topic to a rest.

Thank you for taking time to elaborate the log entry!