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Opened 6 years ago

Last modified 4 years ago

#11695 new defect

radvd picks link-local IPv6 for RDNSS section (while LuCI displays global address)

Reported by: atlan@… Owned by: developers
Priority: normal Milestone: Barrier Breaker 14.07
Component: packages Version: Trunk
Keywords: radvd Cc:

Description

When the address is left empty, LuCI chooses and displays the global IPv6 of the interface (which seems to be the right choice), however the radvd script specifically picks link-local address:

On LuCI:
Interface:
Enable Interface Address Lifetime
lan:
2601:D:xxxx:xxxx:C63D:C7FF:xxxx:xxxx/64
1200

However in /tmp/etc/config/radvd.conf:

RDNSS fe80::c63d:c7ff:fe9e:2369
{
};

Because of this line in radvd:

if [ -z "$addr_list" ]; then

addr=$(get_ip6addr "$IFNAME" link)
return 0

addr_list=" ${addr%%/*}"

fi


Shouldn't radvd pick the global address so that the router's own dnsmasq is advertised to hosts on the network? Right now, I can't use RDNSS because my provider assigns IPv6 prefixes through DHCPv6 (and so the address might change).

Attachments (0)

Change History (4)

comment:1 Changed 6 years ago by atlan@…

BTW, this is the same on backfire.

comment:2 Changed 5 years ago by anonymous

This is a problem on AA. If the ISP issues dynamic IPv6, one cannot workaround the issue with a fixed IPv6 address on the RDNSS option of radvd configuration.

comment:3 Changed 5 years ago by simon.vetter@…

I am using

addr=$(get_ip6addr "$IFNAME" global) ||  addr=$(get_ip6addr "$IFNAME" link) || return 0

in the /etc/init.d/radvd script. This way, if a global scope address is available, it will be used. If not, the link local address will be used.

It works fine with Comcast which assigns somewhat static prefixes to customers with DHCP-PD.

Isn't the init script supposed to regenerate radvd.conf after a prefix change? In this case, the new global address would be picked up by the script, put in the config file and advertised by radvd on the network.

The old address would be phased out of client resolvers quickly because

  • RDNSS options are advertised with a lifetime of 600 seconds
  • after noticing the change, radvd will withdraw it by issuing an advertisement with a lifetime of 0 second (effectively saying "this DNS is not valid anymore")

comment:4 Changed 4 years ago by jow

  • Milestone changed from Attitude Adjustment 12.09 to Barrier Breaker 14.07

Milestone Attitude Adjustment 12.09 deleted

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