From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by passt.top (Postfix) with ESMTP id 7E8B05A0265 for ; Wed, 26 Oct 2022 15:41:23 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666791682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xMKoGkMRsS+BLB+8XWU9KmS+BeYdX7/988uPaDUyFkY=; b=I6gzpPrGpzXYeRJEYvlHkCu5ez+1SgFeIdJAnLDYNhi4/4wLnHWShI1taBiTdMg8CJbod/ gARtuKnqA+ErUhIB1wc2T8yTlwKtBtoNuYGOfcfEhSDA9sUPT190yY6cPFgo7Ael+XP+v9 XX9RfJ5d606FGmq325jpMzo8YVe67vQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-595-eoVbTXJBOHywE6FmXHpTbA-1; Wed, 26 Oct 2022 09:41:21 -0400 X-MC-Unique: eoVbTXJBOHywE6FmXHpTbA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 001C2882820; Wed, 26 Oct 2022 13:41:19 +0000 (UTC) Received: from maya.cloud.tilaa.com (ovpn-208-31.brq.redhat.com [10.40.208.31]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7B0D71401C2F; Wed, 26 Oct 2022 13:41:11 +0000 (UTC) Date: Wed, 26 Oct 2022 15:40:56 +0200 From: Stefano Brivio To: Paul Holzinger Subject: Re: [PATCH] checksum: Fix calculation for ICMP checksum on IPv4 Message-ID: <20221026154056.5a881b91@elisabeth> In-Reply-To: References: <20221025160713.1024373-1-sbrivio@redhat.com> <20221026145750.49fd26da@elisabeth> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: OVHQFUUKU7T32NRHIFCKFZZLHSBM3XCY X-Message-ID-Hash: OVHQFUUKU7T32NRHIFCKFZZLHSBM3XCY X-MailFrom: sbrivio@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: David Gibson , passt-dev@passt.top X-Mailman-Version: 3.3.3 Precedence: list List-Id: Development discussion and patches for passt Archived-At: <> Archived-At: List-Archive: <> List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Wed, 26 Oct 2022 15:07:42 +0200 Paul Holzinger wrote: > Pcap file is attached. Thanks, it's not the issue I had in mind. Here the ARP exchange already happened, and the ICMP proxy is not tracking the first reply. We might be using this kind of mechanism here, if bind() for ICMP echo sockets is not allowed on the host: https://passt.top/passt/commit/?id=9663378d6d6dcd8275d60b826356cc4be0538231 (this issue was seen in KubeVirt with passt). But I don't have a clear explanation as to why that first reply is ignored, yet. I'll need to look further into this. > > This difference is due to the fact that pasta allows any IP address to > > be used by the container, and it will learn that on the first packet. I > > see the same exact behaviour. We might be able to improve this, but I'm > > not entirely sure. > > I might misunderstand how passt/pasta work but it already configured the > interface in the netns with the correct ip, no? Why does it need to learn > it? Not in general. Podman is passing --config-net, so we can be reasonably (but not totally) sure that that's going to be the address used in the future -- the user could still change it manually. In other cases, we might be offering zero or more of DHCP, NDP, DHCPv6, depending on configuration, and nobody guarantees that the container or a guest is actually implementing that. -- Stefano