dhcpcd-discuss

Hi Klemens

On 23/09/2018 15:50, Klemens Nanni wrote:
> Since SLAAC is handled by slaacd(8)[0], dhcpcd is only used for configuring DNS.
>
> Specifically:
>
> 	$ sysctl -n kern.version
> 	OpenBSD 6.4-beta (GENERIC.MP) #300: Tue Sep 18 02:27:17 MDT 2018
> 	    deraadt@xxxxxxxxxxxxxxxxx:/usr/src/sys/arch/amd64/compile/GENERIC.MP
> 	
> 	$ dhcpcd --version
> 	dhcpcd 7.0.8
> 	Copyright (c) 2006-2018 Roy Marples
> 	Compiled in features: INET ARP ARPing IPv4LL INET6 DHCPv6 AUTH
> 	$ rcctl get dhcpcd flags
> 	trunk0
> 	$ cat /etc/dhcpcd.conf
> 	background
> 	persistent
> 	ipv6only
> 	ipv6ra_noautoconf
> 	option  domain_name domain_name_servers domain_search
> 	require domain_name_servers
>
> slaacd configures IPs and dhcpcd successfully fills /etc/resolv.conf, but as a
> negative side effect of `ipv6ra_noautoconf' the interface's AUTOCONF6 flag is
> deconfigured as well:
>
> 	$ ifconfig trunk0 inet6
> 	trunk0: flags=208943<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,AUTOCONF6> mtu 1500
> 		lladdr 68:f7:28:89:4d:4d
> 		index 6 priority 0 llprio 3
> 		trunk: trunkproto failover
> 			trunkport iwm0 active
> 			trunkport em0 master
> 		groups: trunk egress
> 		media: Ethernet autoselect
> 		status: active
> 		inet6 fe80::d812:af1f:3f16:35aa%trunk0 prefixlen 64 scopeid 0x6
> 		inet6 fd00::73a9:9368:877:4da8 prefixlen 64 autoconf pltime 604100 vltime 2591300
> 		inet6 fd00::6e0e:2840:1717:1f8f prefixlen 64 autoconf autoconfprivacy pltime 71800 vltime 590451
> 		inet6 2001:xxxx:xxxx:1efd:c364:df18:f3b4:29b9 prefixlen 64 autoconf pltime 604100 vltime 2591300
> 		inet6 2001:xxxx:xxxx:1efd:f1d2:36ae:1034:f8d9 prefixlen 64 autoconf autoconfprivacy pltime 71661 vltime 590451
> 	# rcctl restart dhcpcd
> 	dhcpcd(ok)
> 	dhcpcd(ok)
> 	$ ifconfig trunk0 | head -n1
> 	trunk0: flags=8943<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>
> As lifetimes run out and AUTOCONF6 is not set again unless manually with
> `ifconfig trunk0 inet6 autoconf', slaacd stops configuring new addresses and I
> eventually end up with all addresses being deprecated, hence no working uplink.
>
> Is there some way to tell dhcpcd to handle only DNS and *not* touch the interface flag?
>
> 0:	http://man.openbsd.org/slaacd

It's not currently that granular.
See a recent discussion on this here:
https://roy.marples.name/archives/dhcpcd-discuss/0001932.html

I also find it rather odd that you even need to run dhcpcd for DNS as 
the slaacd man page states it supports RFC 8106 which is all about DNS 
in the RA and nothing else.

Is there a compelling reason why you need to run both? Either dhcpcd or 
slaacd should be fine.

Roy