Firewall blocking IPv6 multicast of at least FF02::1:2

[SvenRoederer]

Current Lede17.01 based Hedy-build logging this error quite often:

daemon.err odhcp6c[1556]: Failed to send DHCPV6 message to ff02::1:2 (Permission denied)

As per IANA (https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml#link-local) this is "All-dhcp-agents | [RFC3315]".

Should we really block this? Looks like the firewall-settings should be reviewed.

[SvenRoederer]

• it might be a bad idea to flush the original-LEDE firewall-settings in https://github.com/freifunk-berlin/firmware-packages/blob/cc46996031aa338042f41ccc3c24fa7c319b9799/defaults/freifunk-berlin-firewall-defaults/uci-defaults/freifunk-berlin-firewall-defaults#L7 instead of just adding ours.
• Possibly related to https://github.com/freifunk-berlin/firmware-packages/pull/113 as the upstream "freifunk-defaults" file has some firewall-settings

[SvenRoederer]

this can also be seen in https://lists.berlin.freifunk.net/pipermail/berlin/2019-January/038786.html