Setting up dhcpv6 client

Installing and Using OpenWrt Network and Wireless Configuration
1

I'm trying to set up ipv6 address of my raspi running openwrt using dhpcv6. The address should be obtained from another router (running openwrt too). That server has odhcp server running and my laptop has no problem obtaining ipv6.

When I use odhcp6c on raspberry pi, I can see that server is responding (see request and response with tcpdump), but odhcp6c on raspberry pi is just frozen (like waiting for response). I've ran tcpdump on raspi, so it's getting response from odhcp6 server (not blocked by firewall).

In luci overview I see that there no devices configured for IPv6 Upstream.
I'm also using static ipv4 address to the same router.

So network configuration looks like (there is only lan interface on raspi):

config interface 'lan'
        option ifname 'eth0'
        option proto 'static'
        option ipaddr '192.168.82.192'
        option netmask '255.255.255.0'
        option gateway '192.168.82.1'
        option dns '8.8.8.8'
        option ip6assign '64'

Not sure, if it may be the cause (should not be), but I uninstalled odhcp (daemon) and installed dnsmasq-full, because I wanted dnssec. Is daemon necessary for client only scenario? Thanks for help.

1 Like
2

From the OpenWrt client device:

uci show network; uci show firewall
3 
network.loopback=interface
network.loopback.ifname='lo'
network.loopback.proto='static'
network.loopback.ipaddr='127.0.0.1'
network.loopback.netmask='255.0.0.0'
network.lan=interface
network.lan.ifname='eth0'
network.lan.proto='static'
network.lan.ipaddr='192.168.82.192'
network.lan.netmask='255.255.255.0'
network.lan.gateway='192.168.82.1'
network.lan.dns='8.8.8.8'
network.lan.ip6assign='64'
network.vpntun=interface
network.vpntun.proto='none'
network.vpntun.ifname='tun0'
network.@route[0]=route
network.@route[0].interface='lan'
network.@route[0].target='192.168.83.0'
network.@route[0].netmask='255.255.255.0'
network.@route[0].gateway='192.168.82.1'
network.@route[1]=route
network.@route[1].interface='lan'
network.@route[1].target='192.168.81.0'
network.@route[1].netmask='255.255.255.0'
network.@route[1].gateway='192.168.82.1'
firewall.@defaults[0]=defaults
firewall.@defaults[0].syn_flood='1'
firewall.@defaults[0].input='ACCEPT'
firewall.@defaults[0].output='ACCEPT'
firewall.@defaults[0].forward='ACCEPT'
firewall.@zone[0]=zone
firewall.@zone[0].name='lan'
firewall.@zone[0].input='ACCEPT'
firewall.@zone[0].output='ACCEPT'
firewall.@zone[0].forward='ACCEPT'
firewall.@zone[0].network='lan'
firewall.@zone[1]=zone
firewall.@zone[1].name='wan'
firewall.@zone[1].input='REJECT'
firewall.@zone[1].output='ACCEPT'
firewall.@zone[1].forward='REJECT'
firewall.@zone[1].masq='1'
firewall.@zone[1].mtu_fix='1'
firewall.@zone[1].network='wan wan6'
firewall.@rule[0]=rule
firewall.@rule[0].name='Allow-DHCP-Renew'
firewall.@rule[0].src='wan'
firewall.@rule[0].proto='udp'
firewall.@rule[0].dest_port='68'
firewall.@rule[0].target='ACCEPT'
firewall.@rule[0].family='ipv4'
firewall.@rule[1]=rule
firewall.@rule[1].name='Allow-Ping'
firewall.@rule[1].src='wan'
firewall.@rule[1].proto='icmp'
firewall.@rule[1].icmp_type='echo-request'
firewall.@rule[1].family='ipv4'
firewall.@rule[1].target='ACCEPT'
firewall.@rule[2]=rule
firewall.@rule[2].name='Allow-IGMP'
firewall.@rule[2].src='wan'
firewall.@rule[2].proto='igmp'
firewall.@rule[2].family='ipv4'
firewall.@rule[2].target='ACCEPT'
firewall.@rule[3]=rule
firewall.@rule[3].name='Allow-DHCPv6'
firewall.@rule[3].src='wan'
firewall.@rule[3].proto='udp'
firewall.@rule[3].src_ip='fc00::/6'
firewall.@rule[3].dest_ip='fc00::/6'
firewall.@rule[3].dest_port='546'
firewall.@rule[3].family='ipv6'
firewall.@rule[3].target='ACCEPT'
firewall.@rule[4]=rule
firewall.@rule[4].name='Allow-MLD'
firewall.@rule[4].src='wan'
firewall.@rule[4].proto='icmp'
firewall.@rule[4].src_ip='fe80::/10'
firewall.@rule[4].icmp_type='130/0' '131/0' '132/0' '143/0'
firewall.@rule[4].family='ipv6'
firewall.@rule[4].target='ACCEPT'
firewall.@rule[5]=rule
firewall.@rule[5].name='Allow-ICMPv6-Input'
firewall.@rule[5].src='wan'
firewall.@rule[5].proto='icmp'
firewall.@rule[5].icmp_type='echo-request' 'echo-reply' 'destination-unreachable' 'packet-too-big' 'time-exceeded' 'bad-header' 'unknown-header-type' 'router-solicitation' 'neighbour-solicitation' 'router-advertisement' 'neighbour-advertisement'
firewall.@rule[5].limit='1000/sec'
firewall.@rule[5].family='ipv6'
firewall.@rule[5].target='ACCEPT'
firewall.@rule[6]=rule
firewall.@rule[6].name='Allow-ICMPv6-Forward'
firewall.@rule[6].src='wan'
firewall.@rule[6].dest='*'
firewall.@rule[6].proto='icmp'
firewall.@rule[6].icmp_type='echo-request' 'echo-reply' 'destination-unreachable' 'packet-too-big' 'time-exceeded' 'bad-header' 'unknown-header-type'
firewall.@rule[6].limit='1000/sec'
firewall.@rule[6].family='ipv6'
firewall.@rule[6].target='ACCEPT'
firewall.@rule[7]=rule
firewall.@rule[7].name='Allow-IPSec-ESP'
firewall.@rule[7].src='wan'
firewall.@rule[7].dest='lan'
firewall.@rule[7].proto='esp'
firewall.@rule[7].target='ACCEPT'
firewall.@rule[8]=rule
firewall.@rule[8].name='Allow-ISAKMP'
firewall.@rule[8].src='wan'
firewall.@rule[8].dest='lan'
firewall.@rule[8].dest_port='500'
firewall.@rule[8].proto='udp'
firewall.@rule[8].target='ACCEPT'
firewall.@include[0]=include
firewall.@include[0].path='/etc/firewall.user'
firewall.@zone[2]=zone
firewall.@zone[2].name='vpn'
firewall.@zone[2].output='ACCEPT'
firewall.@zone[2].network='vpntun'
firewall.@zone[2].forward='REJECT'
firewall.@zone[2].masq='1'
firewall.@zone[2].mtu_fix='1'
firewall.@zone[2].input='REJECT'
4

Try to configure DHCPv6 client as a non-bridge alias lan6:

Also add lan6 network to the firewall lan zone and then check:

ifup lan6; sleep 10; ifstatus lan6
5

So I did add alias to network

config interface 'wan6'
        option ifname 'eth0'
        option proto 'dhcpv6'

ifup wan6; sleep 10; ifstatus wan6

Just saw error in syslog:

Sat Aug 31 11:38:08 2019 daemon.err odhcp6c[8713]: Failed to send RS (Address not available)
Sat Aug 31 11:38:08 2019 user.notice firewall: Reloading firewall due to ifup of lan (eth0)
Sat Aug 31 11:38:09 2019 daemon.err odhcp6c[8713]: Failed to send DHCPV6 message to ff02::1:2 (Address not available)
6

A similar error:

Verify that you are using the latest stable OpenWrt release:

ubus call system board

Restart the firewall and network services:

service firewall restart
service network restart

Check the interface IPv6 configuration and NDP cache:

ip -6 address show dev eth0
ip -6 neigh show
7

Many thanks for you assistence.

{
	"kernel": "4.19.42-aufs",
	"hostname": "Rasputin",
	"system": "ARMv6-compatible processor rev 7 (v6l)",
	"model": "Raspberry Pi Model B Rev 1",
	"board_name": "brcm,bcm2835",
	"release": {
		"distribution": "OpenWrt",
		"version": "18.06.4",
		"revision": "r7808-ef686b7292",
		"target": "brcm2708\/bcm2708",
		"description": "OpenWrt 18.06.4 r7808-ef686b7292"
	}
}

which brought me, to the question if it's not kernel related. I'm using newer kernel (but from raspi org sources).

Any way: ip -6 address show dev eth0 shows:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 fe80::ba27:ebff:fe05:598/64 scope link 
       valid_lft forever preferred_lft forever

And ip -6 neigh show:

fe80::ba27:ebff:fe05:598 dev eth0 lladdr b8:27:eb:05:05:98 used 0/0/0 probes 0 STALE
8

Just rebooted the router (the one with odhcp daemon running) and it's working now. OMG. Not sure why restarting firewall and network was not enough. But thank you so much, the net alias seems to be necessary anyway.

1 Like
9

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