Hi folks, Happy New Year to start with.
My laptop is hooking up to a no-frills WLAN behind a Debian router advertising a prefix using radvd. I've used this laptop for years in similar situations, but this time I am seeing the kernel warn about duplicate IPv6 addresses being detected: IPv6: wifi: IPv6 duplicate address 2001:4428:29c:0:2ad2:44ff:fe8c:5bd detected! I've unplugged/disconnected all other devices and yet the problem persists. Hence I fired up tcpdump and captured the ICMPv6 packages. And curiously, the laptop is sending two solicitations, one to the multicast MAC address 33:33:ff:* and the other *to itself*! Attached are the two packet dumps, and here's a diff between them, with timestamps and identical stuff stripped: -Frame 1: 78 bytes on wire (624 bits), 78 bytes captured (624 bits) on interface 0 +Frame 2: 78 bytes on wire (624 bits), 78 bytes captured (624 bits) on interface 0 […] -Ethernet II, Src: 28:d2:44:8c:05:bd, Dst: 33:33:ff:8c:05:bd - Destination: 33:33:ff:8c:05:bd - Address: 33:33:ff:8c:05:bd - .... ..1. .... .... .... .... = LG bit: Locally administered address (this is NOT the factory default) - .... ...1 .... .... .... .... = IG bit: Group address (multicast/broadcast) +Ethernet II, Src: 28:d2:44:8c:05:bd, Dst: 28:d2:44:8c:05:bd + Destination: 28:d2:44:8c:05:bd + Address: 28:d2:44:8c:05:bd + .... ..0. .... .... .... .... = LG bit: Globally unique address (factory default) + .... ...0 .... .... .... .... = IG bit: Individual address (unicast) Correct me if I am wrong, but that second frame should not be sent, right? Why would the node send a solicitation to itself? Unfortunately, I have no idea where this is coming from. I've disabled all bridges. This is Debian's 4.3.0-1-amd64 kernel (4.3.3-1). Do you have any clue what might be going on? -- .''`. martin f. krafft <madduck@d.o> @martinkrafft : :' : proud Debian developer `. `'` http://people.debian.org/~madduck `- Debian - when you have better things to do than fixing systems "most people become bankrupt through having invested too heavily in the prose of life. to have ruined one's self over poetry is an honour." -- oscar wilde
Frame 1: 78 bytes on wire (624 bits), 78 bytes captured (624 bits) on interface 0
Interface id: 0 (wifi)
Encapsulation type: Ethernet (1)
Arrival Time: Jan 3, 2016 10:25:50.168744045 NZDT
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1451769950.168744045 seconds
[Time delta from previous captured frame: 0.000000000 seconds]
[Time delta from previous displayed frame: 0.000000000 seconds]
[Time since reference or first frame: 0.000000000 seconds]
Frame Number: 1
Frame Length: 78 bytes (624 bits)
Capture Length: 78 bytes (624 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ipv6:icmpv6]
Ethernet II, Src: 28:d2:44:8c:05:bd, Dst: 33:33:ff:8c:05:bd
Destination: 33:33:ff:8c:05:bd
Address: 33:33:ff:8c:05:bd
.... ..1. .... .... .... .... = LG bit: Locally administered address
(this is NOT the factory default)
.... ...1 .... .... .... .... = IG bit: Group address
(multicast/broadcast)
Source: 28:d2:44:8c:05:bd
Address: 28:d2:44:8c:05:bd
.... ..0. .... .... .... .... = LG bit: Globally unique address
(factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv6 (0x86dd)
Internet Protocol Version 6, Src: ::, Dst: ff02::1:ff8c:5bd
0110 .... = Version: 6
.... 0000 0000 .... .... .... .... .... = Traffic class: 0x00 (DSCP: CS0,
ECN: Not-ECT)
.... 0000 00.. .... .... .... .... .... = Differentiated Services
Codepoint: Default (0)
.... .... ..00 .... .... .... .... .... = Explicit Congestion
Notification: Not ECN-Capable Transport (0)
.... .... .... 0000 0000 0000 0000 0000 = Flowlabel: 0x00000000
Payload length: 24
Next header: ICMPv6 (58)
Hop limit: 255
Source: ::
Destination: ff02::1:ff8c:5bd
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
Internet Control Message Protocol v6
Type: Neighbor Solicitation (135)
Code: 0
Checksum: 0x997e [correct]
Reserved: 00000000
Target Address: 2001:4428:29c:0:2ad2:44ff:fe8c:5bd
Frame 2: 78 bytes on wire (624 bits), 78 bytes captured (624 bits) on interface 0
Interface id: 0 (wifi)
Encapsulation type: Ethernet (1)
Arrival Time: Jan 3, 2016 10:25:50.169511800 NZDT
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1451769950.169511800 seconds
[Time delta from previous captured frame: 0.000767755 seconds]
[Time delta from previous displayed frame: 0.000767755 seconds]
[Time since reference or first frame: 0.000767755 seconds]
Frame Number: 2
Frame Length: 78 bytes (624 bits)
Capture Length: 78 bytes (624 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ipv6:icmpv6]
Ethernet II, Src: 28:d2:44:8c:05:bd, Dst: 28:d2:44:8c:05:bd
Destination: 28:d2:44:8c:05:bd
Address: 28:d2:44:8c:05:bd
.... ..0. .... .... .... .... = LG bit: Globally unique address
(factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: 28:d2:44:8c:05:bd
Address: 28:d2:44:8c:05:bd
.... ..0. .... .... .... .... = LG bit: Globally unique address
(factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IPv6 (0x86dd)
Internet Protocol Version 6, Src: ::, Dst: ff02::1:ff8c:5bd
0110 .... = Version: 6
.... 0000 0000 .... .... .... .... .... = Traffic class: 0x00 (DSCP: CS0,
ECN: Not-ECT)
.... 0000 00.. .... .... .... .... .... = Differentiated Services
Codepoint: Default (0)
.... .... ..00 .... .... .... .... .... = Explicit Congestion
Notification: Not ECN-Capable Transport (0)
.... .... .... 0000 0000 0000 0000 0000 = Flowlabel: 0x00000000
Payload length: 24
Next header: ICMPv6 (58)
Hop limit: 255
Source: ::
Destination: ff02::1:ff8c:5bd
[Source GeoIP: Unknown]
[Destination GeoIP: Unknown]
Internet Control Message Protocol v6
Type: Neighbor Solicitation (135)
Code: 0
Checksum: 0x997e [correct]
Reserved: 00000000
Target Address: 2001:4428:29c:0:2ad2:44ff:fe8c:5bd
digital_signature_gpg.asc
Description: Digital signature (see http://martin-krafft.net/gpg/sig-policy/999bbcc4/current)
