Received packet on eth0 with own address as source address

Installing and Using OpenWrt
21

Ok, thankyou so much, I seem to be making some progress.
For one minute in the system log I got these

Fri Feb  5 17:47:24 2021 kern.warn kernel: [191687.568386] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:25 2021 kern.warn kernel: [191688.572414] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:26 2021 kern.warn kernel: [191689.596465] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:31 2021 kern.warn kernel: [191694.760455] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:32 2021 kern.warn kernel: [191695.772514] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:33 2021 kern.warn kernel: [191696.796439] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:43 2021 kern.warn kernel: [191706.332604] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:43 2021 kern.warn kernel: [191706.343235] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:43 2021 kern.warn kernel: [191706.353472] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:47 2021 kern.warn kernel: [191710.452938] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:48 2021 kern.warn kernel: [191711.484568] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)
Fri Feb  5 17:47:49 2021 kern.warn kernel: [191712.508647] br-lan: received packet on eth0 with own address as source address (addr:dc:a6:32:f2:38:1f, vlan:0)

and in tcpdump output, for the same minute, these

tcpdump -i eth0 -evn -Q in ether src host dc:a6:32:f2:38:1f
---- beginning of minute - some earlier ones removed
17:47:24.527705 dc:a6:32:f2:38:1f > 33:33:ff:71:a3:d3, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff71:a3d3: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:c069:5f8:7a71:a3d3
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:25.531728 dc:a6:32:f2:38:1f > 33:33:ff:71:a3:d3, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff71:a3d3: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:c069:5f8:7a71:a3d3
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:26.555765 dc:a6:32:f2:38:1f > 33:33:ff:71:a3:d3, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff71:a3d3: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:c069:5f8:7a71:a3d3
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:31.719707 dc:a6:32:f2:38:1f > 33:33:ff:71:a3:d3, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff71:a3d3: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:c069:5f8:7a71:a3d3
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:32.731758 dc:a6:32:f2:38:1f > 33:33:ff:71:a3:d3, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff71:a3d3: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:c069:5f8:7a71:a3d3
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:33.755676 dc:a6:32:f2:38:1f > 33:33:ff:71:a3:d3, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff71:a3d3: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:c069:5f8:7a71:a3d3
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:43.291746 dc:a6:32:f2:38:1f > 33:33:ff:f2:38:1f, ethertype IPv6 (0x86dd), length 86: (hlim 1, next-header Options (0) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:fff2:381f: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener reportmax resp delay: 0 addr: ff02::1:fff2:381f
17:47:43.302383 dc:a6:32:f2:38:1f > 33:33:00:01:00:02, ethertype IPv6 (0x86dd), length 86: (hlim 1, next-header Options (0) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:2: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener reportmax resp delay: 0 addr: ff02::1:2
17:47:43.312629 dc:a6:32:f2:38:1f > 33:33:00:01:00:03, ethertype IPv6 (0x86dd), length 86: (hlim 1, next-header Options (0) payload length: 32) fe80::dea6:32ff:fef2:381f > ff05::1:3: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener reportmax resp delay: 0 addr: ff05::1:3
17:47:47.412040 dc:a6:32:f2:38:1f > 33:33:ff:3f:89:84, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff3f:8984: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:387c:d840:583f:8984
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:48.443667 dc:a6:32:f2:38:1f > 33:33:ff:3f:89:84, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff3f:8984: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:387c:d840:583f:8984
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
17:47:49.467739 dc:a6:32:f2:38:1f > 33:33:ff:3f:89:84, ethertype IPv6 (0x86dd), length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32) fe80::dea6:32ff:fef2:381f > ff02::1:ff3f:8984: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who has 2a00:23c4:a993:8700:387c:d840:583f:8984
          source link-address option (1), length 8 (1): dc:a6:32:f2:38:1f
---- end of minute - the rest removed
25 packets captured
3250 packets received by filter
6 packets dropped by kernel
8 packets dropped by interface

It would appear that the number of lines are the same and the timing second is the same in each,

but....

what does it mean?

Thankyou

Richard

22

It means that ICMPv6 NDP packets sent by your machine are reflecting back to the machine. It doesn't seem that you have an amplifying loop at least, otherwise you'd lock up your network.

I'd bet that your mesh re-meshes and when that happens you briefly have a loop. Basically benign.

2 Likes
23

Thankyou very much - benign sounds good.

Shame about the mass of received packet on eth0 with own address as source address log messages

I think tomorrow morning early I will pull all the plugs on the APs and see if these messages disappear. If so, I suppose there is a way of filtering them from the logs, but, first things first.

Thankyou again

Richard

1 Like
24

yeah, that would tell you that the mesh is reflecting them. if they persist then it's the wired hardware somewhere.

1 Like
25

if in case where no plugs in ethernet, so this may be hardware problem.
my wa801nd seems to be striken by thunderbolt, so despite working wifi and other fabric I have looped ethernet (tx to rx) inside SoC and so have messages like yours. They appears every time packet sends outside, e.g. ping something different from own address.