From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [RFC Patch net-next] inet: introduce a sysctl ip_local_ports_strict_use Date: Wed, 22 Jul 2015 22:39:04 -0700 Message-ID: <20150722223904.20ef9011@uryu.home.lan> References: <1437610057-13197-1-git-send-email-xiyou.wangcong@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, edumazet@google.com, davem@davemloft.net To: Cong Wang Return-path: Received: from mail-pa0-f44.google.com ([209.85.220.44]:34916 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750771AbbGWFjI (ORCPT ); Thu, 23 Jul 2015 01:39:08 -0400 Received: by pabkd10 with SMTP id kd10so79396203pab.2 for ; Wed, 22 Jul 2015 22:39:07 -0700 (PDT) In-Reply-To: <1437610057-13197-1-git-send-email-xiyou.wangcong@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 22 Jul 2015 17:07:37 -0700 Cong Wang wrote: > For a real example, named randomly selects some port to bind() for > security concern. (It doesn't use bind(0) to let kernel to select port > because it is not random enough, kernel usually just picks the next > available.) When running named on a Mesos controlled host, named would > silently fail when it binds a port assigned to a Mesos container. I think named is trying to workaround security issues that were fixed 5 years ago in Linux. The kernel does not just pick the next available in current code.