From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniele Orlandi Subject: Issue with ping source address display Date: Tue, 12 Apr 2016 19:52:15 +0200 Message-ID: <570D35CF.9070006@orlandi.com> Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms090001050702020307090303" To: netdev@vger.kernel.org Return-path: Received: from submission.geniusware.it ([62.212.12.144]:45606 "EHLO submission.geniusware.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757242AbcDLSBC (ORCPT ); Tue, 12 Apr 2016 14:01:02 -0400 Received: from localhost (localhost [127.0.0.1]) by submission.orlandi.com (Postfix) with ESMTP id 9E0F04C0483 for ; Tue, 12 Apr 2016 19:52:16 +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 14g120UwesbI for ; Tue, 12 Apr 2016 19:52:15 +0200 (CEST) Received: from [IPv6:2a02:20:20::20] (unknown [IPv6:2a02:20:20::20]) (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 D257B4C002E for ; Tue, 12 Apr 2016 19:52:15 +0200 (CEST) Sender: netdev-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms090001050702020307090303 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hello, More than one year ago I posted the following message but it hasn't received a reply, now I've been stung by a similar issue, you may want to investigate: 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. =46rom 192.168.1.1 icmp_seq=3D1 Destination Host Unreachable =46rom 192.168.1.1 icmp_seq=3D2 Destination Host Unreachable =46rom 192.168.1.1 icmp_seq=3D3 Destination Host Unreachable 64 bytes from 192.168.1.1: icmp_seq=3D4 ttl=3D61 time=3D24.7 ms 64 bytes from 192.168.1.1: icmp_seq=3D5 ttl=3D61 time=3D25.6 ms 64 bytes from 192.168.1.1: icmp_seq=3D6 ttl=3D61 time=3D69.6 ms =46rom 192.168.1.1 icmp_seq=3D7 Destination Host Unreachable =46rom 192.168.1.1 icmp_seq=3D8 Destination Host Unreachable =46rom 192.168.1.1 icmp_seq=3D9 Destination Host Unreachable ^C --- 10.254.10.140 ping statistics --- 9 packets transmitted, 3 received, +6 errors, 66% packet loss, time 8001m= s rtt min/avg/max/mdev =3D 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 decod= e 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=3D9 received=3D3 packet-loss=3D66% min-rtt=3D20ms avg-rtt=3D34ms= max-rtt=3D46ms Recently I was pinging with IPv6, a router in between filtered the packet, however the shown source address was not the right one: root@monitor:~# ping6 -i 0.2 www.google.com PING www.google.com(mil01s25-in-x04.1e100.net) 56 data bytes =46rom mil01s25-in-x04.1e100.net icmp_seq=3D1 Destination unreachable: No= route =46rom mil01s25-in-x04.1e100.net icmp_seq=3D2 Destination unreachable: No= route =46rom mil01s25-in-x04.1e100.net icmp_seq=3D3 Destination unreachable: No= route 19:33:19.589285 IP6 2a01:2d8:aca0:fce:944e:c8ff:fe4d:96de > mil01s25-in-x04.1e100.net: ICMP6, echo request, seq 1, length 64 19:33:19.611666 IP6 mix-br2.intercom.it > 2a01:2d8:aca0:fce:944e:c8ff:fe4d:96de: ICMP6, destination unreachable, unreachable route mil01s25-in-x04.1e100.net, length 112 Bye, 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