Return-Path: Received: from out01.mta.xmission.com ([166.70.13.231]:34366 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030992AbdEWPYJ (ORCPT ); Tue, 23 May 2017 11:24:09 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: David Howells Cc: Aleksa Sarai , James Bottomley , trondmy@primarydata.com, mszeredi@redhat.com, linux-nfs@vger.kernel.org, jlayton@redhat.com, Linux Containers , linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org References: <87zie3mxkc.fsf@xmission.com> <149547014649.10599.12025037906646164347.stgit@warthog.procyon.org.uk> <1495472039.2757.19.camel@HansenPartnership.com> <2446.1495551216@warthog.procyon.org.uk> <2961.1495552481@warthog.procyon.org.uk> Date: Tue, 23 May 2017 10:17:26 -0500 In-Reply-To: <2961.1495552481@warthog.procyon.org.uk> (David Howells's message of "Tue, 23 May 2017 16:14:41 +0100") Message-ID: <87bmqjmwl5.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [RFC][PATCH 0/9] Make containers kernel objects Sender: linux-nfs-owner@vger.kernel.org List-ID: David Howells writes: > Eric W. Biederman wrote: > >> > As an example, I could set up a client machine with two ethernet ports, >> > set up two DNS+NFS servers, each of which think they're called "foo.bar" >> > and attach each server to a different port on the client machine. Then I >> > could create a pair of containers on the client machine and route the >> > network in each container to a different port. Now there's a problem >> > because the names of the cached DNS records for each port overlap. >> >> Please look at ip netns add. > > warthog>man ip | grep setns > warthog1> Not setns netns >> It does solve this in userspace rather simply. > > Ummm... How? The kernel DNS resolver is not namespace aware. But it works fine if called in the proper context and we have a defacto standard for where to put all of the files (the tricky part) if you are dealing with multiple network namespaces simultaneously. Eric