Libvirt provides a portable, long term stable C API for managing the virtualization technologies provided by many operating systems. It includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER Hypervisor.
Go to file
Laine Stump f69a6b987d network: only prevent forwarding of DNS requests for unqualified names
In commit f386825 we began adding the options

  --domain-needed
  --local=/$mydomain/

to all dnsmasq commandlines with the stated reason of preventing
forwarding of DNS queries for names that weren't fully qualified
domain names ("FQDN", i.e. a name that included some "."s and a domain
name). This was later changed to

  domain-needed
  local=/$mydomain/

when we moved the options from the dnsmasq commandline to a conf file.

The original patch on the list, and discussion about it, is here:

  https://www.redhat.com/archives/libvir-list/2012-August/msg01594.html

When a domain name isn't specified (mydomain == ""), the addition of
"domain-needed local=//" will prevent forwarding of domain-less
requests to the virtualization host's DNS resolver, but if a domain
*is* specified, the addition of "local=/domain/" will prevent
forwarding of any requests for *qualified* names within that domain
that aren't resolvable by libvirt's dnsmasq itself.

An example of the problems this causes - let's say a network is
defined with:

   <domain name='example.com'/>
   <dhcp>
      ..
      <host mac='52:54:00:11:22:33' ip='1.2.3.4' name='myguest'/>
   </dhcp>

This results in "local=/example.com/" being added to the dnsmasq options.

If a guest requests "myguest" or "myguest.example.com", that will be
resolved by dnsmasq. If the guest asks for "www.example.com", dnsmasq
will not know the answer, but instead of forwarding it to the host, it
will return NOT FOUND to the guest. In most cases that isn't the
behavior an admin is looking for.

A later patch (commit 4f595ba) attempted to remedy this by adding a
"forwardPlainNames" attribute to the <dns> element. The idea was that
if forwardPlainNames='yes' (default is 'no'), we would allow
unresolved names to be forwarded. However, that patch was botched, in
that it only removed the "domain-needed" option when
forwardPlainNames='yes', and left the "local=/mydomain/".

Really we should have been just including the option "--domain-needed
--local=//" (note the lack of domain name) regardless of the
configured domain of the network, so that requests for names without a
domain would be treated as "local to dnsmasq" and not forwarded, but
all others (including those in the network's configured domain) would
be forwarded. We also shouldn't include *either* of those options if
forwardPlainNames='yes'. This patch makes those corrections.

This patch doesn't remedy the fact that default behavior was changed
by the addition of this feature. That will be handled in a subsequent
patch.
2014-02-04 12:00:26 +02:00
.gnulib@d5fec6c22f maint: update to latest gnulib, for mingw improvements 2014-01-23 15:21:59 -07:00
build-aux Make syntax check notice assignments w/o surrounding spaces. 2014-01-20 14:35:26 +01:00
daemon build: add $(prefix) to SYSTEMD_UNIT_DIR 2014-01-21 13:19:46 +02:00
docs docs/page.xls: remove unnecessary namespace attribute 2014-01-30 15:37:38 +01:00
examples maint: align whitespaces with project conventions. 2014-01-20 14:35:08 +01:00
gnulib maint: update to latest gnulib 2014-01-01 06:02:47 -07:00
include Block info query: Add check for transient domain 2014-01-24 11:37:18 -05:00
m4 aarch64: Disable -fstack-protector. 2014-01-01 14:21:21 +00:00
po Release of libvirt-1.2.1 2014-01-16 17:25:58 +08:00
src network: only prevent forwarding of DNS requests for unqualified names 2014-02-04 12:00:26 +02:00
tests network: only prevent forwarding of DNS requests for unqualified names 2014-02-04 12:00:26 +02:00
tools build: Fix 'make rpm' in VPATH with wireshark 2014-02-04 10:57:21 +01:00
.ctags maint: Make ctags work out of the box 2013-07-18 08:47:21 +02:00
.dir-locals.el build: avoid tabs that failed syntax-check 2012-09-06 09:43:46 -06:00
.gitignore tests: Add tests for scsi utils 2014-01-30 15:50:37 +08:00
.gitmodules make .gnulib a submodule 2009-07-08 16:17:51 +02:00
.mailmap Autogenerate AUTHORS 2012-10-19 12:44:56 -04:00
AUTHORS.in Add Pavel Hrdina to the committers list 2014-01-16 14:47:02 +01:00
autobuild.sh Remove python binding 2013-11-25 16:08:00 +00:00
autogen.sh autogen.sh: Correctly detect .git as a file 2013-08-29 13:19:45 +02:00
bootstrap maint: update to latest gnulib 2014-01-01 06:02:47 -07:00
bootstrap.conf Add helpers for getting env vars in a setuid environment 2013-10-21 14:03:52 +01:00
cfg.mk Introduce Libvirt Wireshark dissector 2014-01-20 17:09:41 +01:00
ChangeLog-old maint: typo fixes 2013-10-22 16:49:32 +01:00
config-post.h build: fix build of virt-login-shell on systems with older gnutls 2013-10-22 09:41:50 -06:00
configure.ac Remove windows thread implementation in favour of pthreads 2014-01-30 18:00:20 +00:00
COPYING maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
COPYING.LESSER maint: follow recommended practice for using LGPL 2013-05-20 14:15:21 -06:00
HACKING maint: enforce comma style usage 2013-11-20 09:24:18 -07:00
libvirt.pc.in Add missing 'libvirt_lxc_api' variable in pkg-config file 2013-09-04 14:52:40 +01:00
libvirt.spec.in Release of libvirt-1.2.1 2014-01-16 17:25:58 +08:00
Makefile.am Introduce Libvirt Wireshark dissector 2014-01-20 17:09:41 +01:00
Makefile.nonreentrant maint: use LGPL correctly 2013-05-20 14:03:48 -06:00
mingw-libvirt.spec.in Remove python binding 2013-11-25 16:08:00 +00:00
README Correct typos in the documentation (Atsushi SAKAI) 2008-01-24 10:15:13 +00:00
README-hacking maint: relax git minimum version 2010-02-24 14:29:27 -05:00
run.in Remove python binding 2013-11-25 16:08:00 +00:00
TODO Update todo list file to point at bugzilla/website 2010-10-13 16:45:26 +01:00

         LibVirt : simple API for virtualization

  Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.

Daniel Veillard <veillard@redhat.com>