radvd - Too many addresses in RDNSS section when previously using DHCPv6
I have come across a bug within the IPv6 Router Advertising Daemon where you receive the following errors in the logs:
Oct 23 20:40:59 radvd 17699 version 1.9.1 started
Oct 23 20:40:59 radvd 17699 Too many addresses in RDNSS section
Oct 23 20:40:59 radvd 17699 error parsing or activating the config file: /var/etc/radvd.conf
Oct 23 20:40:59 radvd 17699 Exiting, failed to read config file.
However there were no DNSv6 servers configured in General Settings nor in RADVD itself as Server 2012 R2 DHCPv6 was handling this. Having browsed /var/etc/radvd.conf I found there were some stale DNSv6 addresses from a previous ISP in there. So I cleared the file and restarted RADVD. However DNSv6 addresses returned.
I then examined /cf/conf/config.xml
I did a search for one of the stale DNSv6 entries and I found that where this PFsense had previously been acting as a DHCPv6 server that it had kept the old settings in the <dhcpv6></dhcpv6> despite being disabled. Deleting the entire <dhcpv6></dhcpv6> section in this file, saving and restarting RADVD did resolve the problem.
Seems like that evena after you disable dhcpv6 in PFsense it keeps the settings in the config.xml file. Should this be looked at and potentially omitted somehow if marked as disabled so this does not break RADVD at a later point?
#1 Updated by Travis McMurry about 2 years ago
Since 2.4.3_p1 came out, I have been having a tremendous amount of trouble with IPv6 and RADVD specifically - addresses not being allocated, radvd service erroring exactly as stated above.
Jun 5 23:03:08 radvd 68161 exiting, failed to read config file
Jun 5 23:03:08 radvd 68161 too many addresses in RDNSS section
Jun 5 23:03:08 radvd 68161 version 2.17 started
...repeats with no end in the logs. What I see is IPv6 routing doesn't work anymore.
IPv6 Route Table =========================================================================== Active Routes: If Metric Network Destination Gateway 3 26 ::/0 On-link 1 331 ::1/128 On-link 18 281 2601:582:4400:3353::2000/128 On-link 3 281 fe80::/64 On-link 3 281 fe80::1d98:5e3f:bf6f:7dcd/128 On-link 7 291 fe80::2126:9a1a:28b8:7cb/128 On-link 2 291 fe80::b962:3036:fd00:8fe9/128 On-link 19 291 fe80::bc4f:855:6bb9:fc8b/128 On-link 3 281 fe80::becc:5803:c564:aef5/128 On-link 18 281 fe80::d0ca:641e:876:f612/128 On-link 1 331 ff00::/8 On-link 18 281 ff00::/8 On-link 19 291 ff00::/8 On-link 2 291 ff00::/8 On-link 7 291 ff00::/8 On-link ===========================================================================
Missing IPv6 Routes on the Intranet side (via SLAAC/DHCP6)
fe80::201:5cff:fe88:2c46 (link-local IP of pfSense WAN)
2001:558:0:f891::2 (pfSense WAN IP)
...they're not being advertised.
I'm also seeing the following logs; one per internal interface.
Jun 4 17:29:56 radvd 9480 invalid all-zeros prefix in /var/etc/radvd.conf, line 65 Jun 4 17:29:56 radvd 9480 invalid all-zeros prefix in /var/etc/radvd.conf, line 51 Jun 4 17:29:56 radvd 9480 invalid all-zeros prefix in /var/etc/radvd.conf, line 37 Jun 4 17:29:56 radvd 9480 invalid all-zeros prefix in /var/etc/radvd.conf, line 23 Jun 4 17:29:56 radvd 9480 invalid all-zeros prefix in /var/etc/radvd.conf, line 9 Jun 4 17:29:56 radvd 9480 attempting to reread config file
A cursory search on the web points to possible problems with the router advertisement daemon itself:
https://bugs.archlinux.org/task/57310 (bug/patch for radvd)
https://forum.netgate.com/topic/122983/ipv6-not-working-radvd-core-dumping/2 (bug with radvd, said to be fixed in pfS 2.4.2)