My local broadcast domain just started to get DUP! responses to broadcast pings. I've looked around and can't find out way. A normal ping to the same device does not cause a DUP! The following tcpdump shows that only one mac address is responding to the ping. What can be doing this?
allan@allandesk /tmp $ ping 192.168.168.255 -b | grep 108
WARNING: pinging broadcast address
64 bytes from 192.168.168.108: icmp_seq=1 ttl=64 time=0.584 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=2 ttl=64 time=0.648 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=3 ttl=64 time=0.603 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=4 ttl=64 time=0.582 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=5 ttl=64 time=0.568 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=6 ttl=64 time=1.22 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=7 ttl=64 time=0.797 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=8 ttl=64 time=0.584 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=9 ttl=64 time=0.590 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=10 ttl=64 time=0.588 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=11 ttl=64 time=0.577 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=12 ttl=64 time=0.651 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=13 ttl=64 time=0.587 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=14 ttl=64 time=0.580 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=15 ttl=64 time=1.05 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=16 ttl=64 time=0.842 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=17 ttl=64 time=0.586 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=18 ttl=64 time=1.26 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=19 ttl=64 time=0.818 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=20 ttl=64 time=0.580 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=21 ttl=64 time=0.594 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=22 ttl=64 time=0.582 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=23 ttl=64 time=0.579 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=24 ttl=64 time=1.18 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=25 ttl=64 time=0.597 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=26 ttl=64 time=0.587 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=27 ttl=64 time=1.05 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=28 ttl=64 time=0.706 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=29 ttl=64 time=1.59 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=30 ttl=64 time=0.605 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=31 ttl=64 time=0.581 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=32 ttl=64 time=0.966 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=33 ttl=64 time=0.603 ms (DUP!)
64 bytes from 192.168.168.108: icmp_seq=34 ttl=64 time=0.587 ms (DUP!)
allandesk allan # tcpdump -en | grep 192.168.168.108
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eno1, link-type EN10MB (Ethernet), capture size 262144 bytes
16:09:00.695973 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 8, length 64
16:09:01.697706 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 9, length 64
16:09:02.699606 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 10, length 64
16:09:03.700713 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 11, length 64
16:09:04.702645 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 12, length 64
16:09:05.704588 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 13, length 64
16:09:06.705676 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 14, length 64
16:09:07.707211 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 15, length 64
16:09:08.708812 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 16, length 64
16:09:09.709673 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 17, length 64
16:09:10.712276 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 18, length 64
16:09:11.713844 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 19, length 64
16:09:12.715584 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 20, length 64
16:09:13.717604 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 21, length 64
16:09:14.719594 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 22, length 64
16:09:15.720497 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 23, length 64
16:09:16.722146 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 24, length 64
16:09:17.722617 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 25, length 64
16:09:18.724536 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 26, length 64
16:09:19.727025 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 27, length 64
16:09:20.728672 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 28, length 64
16:09:21.731551 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 29, length 64
16:09:22.732552 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 30, length 64
16:09:23.734531 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 31, length 64
16:09:24.736899 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 32, length 64
16:09:25.738559 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 33, length 64
16:09:26.739567 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 34, length 64
16:09:27.741846 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 35, length 64
16:09:28.742718 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 36, length 64
16:09:29.744553 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 37, length 64
16:09:30.746586 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 38, length 64
16:09:31.748502 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 39, length 64
16:09:32.751617 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 40, length 64
16:09:33.752513 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 41, length 64
16:09:34.754510 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 42, length 64
16:09:35.756565 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 43, length 64
16:09:36.757260 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 44, length 64
16:09:37.758802 00:10:49:21:81:37 > 38:60:77:89:70:79, ethertype IPv4 (0x0800), length 98: 192.168.168.108 > 192.168.168.140: ICMP echo reply, id 25399, seq 45, length 64
