From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniele Orlandi Subject: Issue with ping source address display Date: Tue, 16 Sep 2014 18:01:05 +0200 Message-ID: <54185EC1.6030303@orlandi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from submission.geniusware.it ([62.212.12.144]:35947 "EHLO submission.geniusware.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754424AbaIPQNu (ORCPT ); Tue, 16 Sep 2014 12:13:50 -0400 Received: from localhost (localhost [127.0.0.1]) by submission.orlandi.com (Postfix) with ESMTP id A60BF4C16D1 for ; Tue, 16 Sep 2014 18:04:13 +0200 (CEST) Received: from submission.orlandi.com ([127.0.0.1]) by localhost (submission.orlandi.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id k9sFFJD5T31J for ; Tue, 16 Sep 2014 18:01:16 +0200 (CEST) Received: from [IPv6:2a02:20:20:cafe:a54d:c65d:d221:340c] (unknown [IPv6:2a02:20:20:cafe:a54d:c65d:d221:340c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: daniele@orlandi.com) by submission.orlandi.com (Postfix) with ESMTPSA id F397A4C16AF for ; Tue, 16 Sep 2014 18:01:15 +0200 (CEST) Sender: netdev-owner@vger.kernel.org List-ID: Hello, I noticed that when ping receives ICMP messages from different sources the first IP address is always used and displayed: vihai@seviolab:~$ ping -V ping utility, iputils-s20121221 This is a (simulated) flapping route: vihai@seviolab:~$ ping 10.254.10.140 PING 10.254.10.140 (10.254.10.140) 56(84) bytes of data. From 192.168.1.1 icmp_seq=1 Destination Host Unreachable From 192.168.1.1 icmp_seq=2 Destination Host Unreachable From 192.168.1.1 icmp_seq=3 Destination Host Unreachable 64 bytes from 192.168.1.1: icmp_seq=4 ttl=61 time=24.7 ms 64 bytes from 192.168.1.1: icmp_seq=5 ttl=61 time=25.6 ms 64 bytes from 192.168.1.1: icmp_seq=6 ttl=61 time=69.6 ms From 192.168.1.1 icmp_seq=7 Destination Host Unreachable From 192.168.1.1 icmp_seq=8 Destination Host Unreachable From 192.168.1.1 icmp_seq=9 Destination Host Unreachable ^C --- 10.254.10.140 ping statistics --- 9 packets transmitted, 3 received, +6 errors, 66% packet loss, time 8001ms rtt min/avg/max/mdev = 24.797/40.061/69.692/20.955 ms The sources, however are different: vihai@seviolab:~$ sudo tcpdump -n icmp tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes ^[OA^[OA^[OA17:09:55.932981 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 1, length 64 17:09:55.933234 IP 192.168.1.1 > 192.168.1.21: ICMP host 10.254.10.140 unreachable, length 92 17:09:56.933169 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 2, length 64 17:09:56.933416 IP 192.168.1.1 > 192.168.1.21: ICMP host 10.254.10.140 unreachable, length 92 17:09:57.933160 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 3, length 64 17:09:57.933404 IP 192.168.1.1 > 192.168.1.21: ICMP host 10.254.10.140 unreachable, length 92 17:09:58.933163 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 4, length 64 17:09:58.957939 IP 10.254.10.140 > 192.168.1.21: ICMP echo reply, id 9278, seq 4, length 64 17:09:59.935050 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 5, length 64 17:09:59.960724 IP 10.254.10.140 > 192.168.1.21: ICMP echo reply, id 9278, seq 5, length 64 17:10:00.936177 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 6, length 64 17:10:01.005849 IP 10.254.10.140 > 192.168.1.21: ICMP echo reply, id 9278, seq 6, length 64 17:10:01.936313 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 7, length 64 17:10:01.936626 IP 192.168.1.1 > 192.168.1.21: ICMP host 10.254.10.140 unreachable, length 92 17:10:02.935321 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 8, length 64 17:10:02.935591 IP 192.168.1.1 > 192.168.1.21: ICMP host 10.254.10.140 unreachable, length 92 17:10:03.934322 IP 192.168.1.21 > 10.254.10.140: ICMP echo request, id 9278, seq 9, length 64 17:10:03.934613 IP 192.168.1.1 > 192.168.1.21: ICMP host 10.254.10.140 unreachable, length 92 Tried with a different ping implementation (RouterOS) and the behaviour seems correct: [vihai@SevioLab SW1] > ping 10.254.10.140 HOST SIZE TTL TIME STATUS 192.168.1.1 84 64 0ms host unreachable 192.168.1.1 84 64 0ms host unreachable 192.168.1.1 84 64 0ms host unreachable 10.254.10.140 56 61 20ms 10.254.10.140 56 61 46ms 10.254.10.140 56 61 37ms 192.168.1.1 84 64 0ms host unreachable 192.168.1.1 84 64 0ms host unreachable 192.168.1.1 84 64 0ms host unreachable sent=9 received=3 packet-loss=66% min-rtt=20ms avg-rtt=34ms max-rtt=46ms I think you may be interested as this issue caught me in a troubleshooting session introducing strangeness and might do the same to you too :) Bye,