netdev - Re: No return for ping -R; not sure if this is the right list

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Message-ID: <CAKoUArn3K+z3++BByQj9Rbm9MFo3k7T=+mvWtjb9Uzhhr8F=EA@mail.gmail.com>
Date:	Thu, 10 Apr 2014 14:35:03 +0300
From:	Rami Rosen <roszenrami@...il.com>
To:	Netdev <netdev@...r.kernel.org>
Subject: Re: No return for ping -R; not sure if this is the right list

Hi, David,

Because of security reasons, many network nodes ignore this IP option.

See man 8 ping:
..
-R ping  only.   Record route.  ...
 Many hosts ignore or discard this option
...


Regards,
Rami Rosen
http://ramirose.wix.com/ramirosen


On Thu, Apr 10, 2014 at 9:59 AM, David Newall <davidn@...idnewall.com> wrote:
> Hello All,
>
> I apologise if this is the wrong list.  It's a user question, not a
> development question, which I wanted to send to the linux-net list, but that
> list no longer exists (according to vger.kernel.org.)  I couldn't find where
> it went, and I'm hoping, if this is not the right place, that someone will
> kindly point me in the proper direction.
>
> My problem is a large number of duplicate ACKs, retransmitted packets, and
> packets out of order.
>
> I'm running Ubuntu 13.10 on a Dell 1920, with Ubuntu's twist of Linux
> 3.11.0-18-generic kernel.  I have two ethernet ports bonded in active-backup
> mode, and bridged with STP on.  I've got a number of virtual hosts running
> on it, using kvm (QEMU 1.5.0, QEMU API 1.1.1) and libvirt (1.1.1).
>
> Some type of Cisco router sits in front of the machine, which is managed by
> the DC who hosts my server.  They also advertise my public IP range with
> BGP.  Apparently there are two independent routes.
>
> I wanted to confirm that the problem is not routing, and thought a number of
> pings with record-route might help, but get no packets returned other than
> when I ping one of the server's own IP addresses.  Even when I ping a
> virtual host with -R, no pings are returned, at least according to ping,
> although I do see them using tcpdump.
>
> They appear to be discarded somewhere on the server, but I cannot find
> where.
>
> It's possible the DC is dropping packets with RR option set, and have sent
> them email asking this to be confirmed and changed, but that does not
> explain why a ping -R to a virtual host doesn't work.
>
> Inserting --proto icmp -j ACCEPT rules in the INPUT, FORWARD & OUTPUT chains
> of the server's iptables' filter table does not help. According to
> /proc/net/ip_tables_names, the only other table is mangle, for which all
> chains are ACCEPT policy and empty, other than POSTROUTING which is ACCEPT
> policy and has CHECKSUM fill rules covering UDP port 68 to two of my virtual
> sub-nets.
>
> There are no iptables rules at all on the target virtual-host.
>
> Even though I'm sure you all already picked up this, just to clear, I am not
> using the iptables ipv4options module, nor, that I can see, any other
> iptables-based rule that would do this.
>
> So, any suggestions to explain what is dropping these pings, or what is
> causing the duplicate acks, retransmits and out-of-order packets, would be
> very gratefully received.  Or, even just a pointer to a better place to ask.
>
> David
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