From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subash Abhinov Kasiviswanathan Subject: Re: [PATCH nf-next] netfilter: nf_defrag_ipv4: Add sysctl to disable per interface Date: Tue, 07 Nov 2017 11:58:40 -0700 Message-ID: <8c74f85d5f668516766ed208cb8eb415@codeaurora.org> References: <1509762520-17873-1-git-send-email-subashab@codeaurora.org> <20171107103013.GA5512@breakpoint.cc> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Cc: netfilter-devel@vger.kernel.org, steffen.klassert@secunet.com, pablo@netfilter.org To: Florian Westphal Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:50774 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751930AbdKGS6l (ORCPT ); Tue, 7 Nov 2017 13:58:41 -0500 In-Reply-To: <20171107103013.GA5512@breakpoint.cc> Sender: netfilter-devel-owner@vger.kernel.org List-ID: > This breaks connection tracking for packets coming in via such > interfaces. > > Nowadays we only enable defrag in a network namespace if the > ip/nftables > ruleset requires it, so this setting would be counter-productive. Hi Florian This usecase is run on an Android based device, so there will be only the init namespace. While the specific rmnet interfaces for wifi calling do not require conntrack / iptables, some other scenarios like NAT on other interfaces may trigger the load of the defrag module. Hence, we needed this interface specific way of preventing defrag. >> An example of this usage is for fixing wifi calling on networks >> where certain routers are configured to drop fragments explicitly. > > Yay... does that happen for all frags or is this related to df bit > somehow? Based on our observations, the routers usually drop all fragmented packets possibly for security reasons. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project