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.
