qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Qemu-devel] [Bug 577908] Re: qemu 0.12.3 default networking DNS broken


From: Irek Szczesniak
Subject: [Qemu-devel] [Bug 577908] Re: qemu 0.12.3 default networking DNS broken
Date: Tue, 28 Dec 2010 13:11:31 -0000

I tested the SLIRP's DNS server of compiled QEMU v. 0.12.5 and v. 0.13.

I created the thread on the Qemu-devel mailing list
(http://lists.nongnu.org/archive/html/qemu-devel/2010-12/msg01893.html),
but I think it's good to restate what I wrote there, especially since
the thread stalled.

I have a problem with the SLIRP's DNS server.  I built from sources
QEMU v 0.13 on Linux debian 2.6.26-2-686 with gcc version 4.3.2
(Debian 4.3.2-1.1).

When I don't pass any network options to QEMU, then I should get a
user networking with SLIRP. According to the man page, QEMU should
create a private network 10.0.2.0/24, and run a DHCP server on
10.0.2.2, and a DNS server on 10.0.2.3.  And indeed such a network is
created, the DHCP server assigns the 10.0.2.15 IP address, but in the
DHCP transaction it seems there is no DNS server mentioned, and my
system complains about a missing DNS server.

Let me describe how I got this problem.  I start the CentOS installer
this way:

qemu -cdrom CentOS-5.5-i386-netinstall.iso

The installer runs, asks questions, and something goes wrong.  On the
third console (Alt + F3 in the virtual machine), I can read errors:

DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 6
DHCPOFFER from 10.0.2.2
DHCPREQUEST on eth0 to 255.255.255.255 port 67
DHCPACK from 10.0.2.2
bound to 10.0.2.15 -- renewal in 33026 seconds.
DHCPv4 eth0 - obtained lease 10.0.2.15
DHCPv4 eth0 - option subnet-mask: 255.255.255.0
DHCPv4 eth0 - option subnet-mask: - prefix_len: 24 broadcast: 10.0.2.255
DHCPv4 eth0 - option routers:
no DNS servers, can't look up hostname

The installer complains that a DNS server is missing, but it seems
that the DHCP also doesn't provide a default gateway.

I ran the installer again, asking it to manually configure the network.
There I put 10.0.2.15/24 as my address, 10.0.2.2 as the default gateway,
and my DNS server.  With those settings, the network worked fine.  Later
in the setup process, I was able to use a shell, and test the DNS at
10.0.2.3.

The interesting thing is that when I tried nslookup with the 10.0.2.3
server, then my requests got resolved.  The installer later in the
process spawns a root shell on tty2, where I issued the nslookup
command.  So it seems that the DNS server works (or starts working after
sometime), but that the DHCP server doesn't mention the DNS server.

Can I help somehow diagnose the problem further?

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/577908

Title:
  qemu 0.12.3 default networking DNS broken

Status in QEMU:
  Incomplete

Bug description:
  This might be something simple and known, but I don't find such 
information... I installed qemu 0.12.3 from source on a Linux/x86-64 host and 
observe that, running a debian testing guest (squeeze netinst, also the 
installed system), the DNS setup that qemu's  DHCP provides is not working.

Namely, nameserver 10.0.2.3 in /etc/resolv.conf (as created by DHCP) does not 
help name resolution, but replacing the IP with my actual DNS server does work. 
Now this is still unfortunate as it is very cumbersome to replace the DNS for 
every system I run in qemu for testing... it used to work before with earlier 
versions.

If there is some easy means to help debug this, I'll try to help... but right 
now I am rather clueless.





reply via email to

[Prev in Thread] Current Thread [Next in Thread]