DHCPv6-PD doesn't work. DHCPv6-server won't start after commiting configuration


I am using VyOS version:

vyos@vyos:~$ show version 
Version:          VyOS 1.3.1
Release train:    sagitta
Built by:         derago@gmail.com
Built on:         Thu 14 Apr 2022 14:19 UTC
Build UUID:       4de5e5e1-16f2-4a5b-a142-4c435d503018
Build commit ID:  5fa31bdccc8bdf
Architecture:     x86_64
Boot via:         installed image
System type:      bare metal

I tried to configure DHCPv6-PD with the following config:

vyos@vyos# show service dhcpv6-server 
 shared-network-name networkname-dhcpv6 {
     subnet 20xx:xxx:xxx:c0::/60 {
         name-server 2001:4860:4860::8888
         prefix-delegation {
             start 20xx:xxx:xxx:d0::100 {
                 prefix-length 64
                 stop 20xx:xxx:xxx:d0::200

And commit works but then when I try to restart dhcpv6-server I get:

vyos@vyos:~$ restart dhcpv6 server 
Job for isc-dhcp-server6.service failed because the control process exited with error code.
See "systemctl status isc-dhcp-server6.service" and "journalctl -xe" for details.

I could post what’s in the journalctl but there is really nothing there. I configured IPv6 in the range of the prefix configured on that interface and IPv6 connectivity is working:

vyos@vyos:~$ show interfaces ethernet eth2 
eth2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 5c:a6:e6:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    inet6 20xx:xxx:xxx:c0::1/60 scope global

I suspect there is some bug. But if someone more experienced in VyOS could shed a light a bit I would be glad. Thanks!

EDIT: But since the server won’t start there is no DHCPv6 leases yet!

Hi @ITGUY , it is not 1.3.1 because Release train: sagitta. You built 1.4 and named it 1.3.1
Let me try to reproduce on 1.4 rolling and maybe it is necessary to describe this bug on the development portal.

In our original 1.3.2 I can not confirm any bugs regarding DHCPv6 server

vyos@vyos:~$ show version | match "Version|Release"
Version:          VyOS 1.3.2
Release train:    equuleus
vyos@vyos:~$ show configuration commands | match dhcpv6
set service dhcpv6-server shared-network-name NET1 subnet 2001:db8::/64 address-range start 2001:db8::100 stop '2001:db8::199'
set service dhcpv6-server shared-network-name NET1 subnet 2001:db8::/64 name-server '2001:db8::ffff'
vyos@vyos:~$ restart dhcpv6 server 
vyos@vyos:~$ ps ax | grep dhcp
 2440 ?        Ss     0:00 /usr/sbin/dhcpd -6 -q -user dhcpd -group nogroup -pf /run/dhcp-server/dhcpdv6.pid -cf /run/dhcp-server/dhcpdv6.cons
 2442 ttyS0    S+     0:00 grep dhcp

UPD: On the latest rolling all works properly

vyos@vyos:~$ show version | match "Version|Release"
Version:          VyOS 1.4-rolling-202210050218
Release train:    sagitta

Hi @Dmitry,
Without PD in config my DHCPv6 server also starts. Please take a look at subnets and prefixes in my config. The subnet is c0::/60 and PD is from d0::/64 range. Could you confirm it works for you as well. If so I will try to upgrade to official nightly builds.

Yes, confirmed. Looks like it is know issue with missing prefix validation


1 Like

Is there some timeline to fix that bug? Some milestone? It’s there already since 2021 :frowning: