Not getting automatic IP address (NAT)
So, I have just switched to KVM for my virtualization needs, and I like it! I have created a couple of VM's (Windows Server 2008), running on my ArchLinux host.
So far, so good apart from the issue that when I start one or two particular VM's they are not getting an IP address from the built-in NAT (10.0.2.x). What's strange is that when I set them up, it worked OK - and I haven't changed anything since; other VM's just work fine, with the exactly same setup.
This is the way I did it (if anyone can spot something particular):
1. I created a new VM (Windows Server 2008) from scratch, let's call it A.img. When I booted up the VM for the first time I received 10.0.2.15 (I assume that's the default KVM NAT "server"), and I could connect to my host and the internet.
2. I then did some installations etc on the guest (A.img), rebooted a couple of times and it worked fine.
3. I copied the VM image to another name (B.img), booted it up and the networking worked fine (received the same 10.0.2.15 address).
4. Made some more installations on B.img, a cuple of reboots and all was OK.
5. Copied B.img to C.img, booted up C.img and networking was OK (10.0.2.15).
6. Went back to A.img, booted it up, and now I'm not getting the 10.0.2.15 (the other VM's - B, C, are not running now), but an address in the 169 range (the address you get in Windows when you can't get an IP from a DHCP server). If I start up B or C all works OK.
7. If I manually assign a 10.0.2.x address to A.img all works.
So, is this something I have done wrong (most likely), or is it a bug, or ...???
Thanks!
Niels
Nielsb,
This may or may not work but you could probably try restarting your dnsmasq service. The script is usually located at /etc/rc.d/init.d/dnsmasq
Also what command line are you using to start your machine?
Hi Haydn,
My command line is something like:
qemu-kvm -m 2048 -std-vga -localtime -hda A.img
after having posted my the original question I did some more googling and came across "-net user", I'll try that next time it happens.
As for dnsmasq; AFAIK/understand I wouldn't need it if I just do user mode networking (10.0.2.x), and I do not have it installed either on my host.
Thanks!!
Niels
Hi Neilsb
You're right, dnsmasq is not needed for userspace. The -net user should be default but try it and let us know.
Hi Haydn,
I'll let you know if it happens again if "-net user" would help.
Thanks!!
Nielsfomuma
I have a similar issue on my Arch Linux laptop. When I'm connected to my wireless network at home, the internal NAT system with DHCP in QEMU works fine, but when I'm at work and connected to their wireless network, the virtual machine doesn't receive a IP-address from QEMU. It's extremely weird.
I haven't had the time to debug this further, it must be a bug somewhere...in qemu or in the kernel perhaps :-/
Kenni
I ran into the same problem - Windows 2008 networking using RTL8139C drivers does not get IP address through DHCP.
Messing around with the options in Windows, I ran into the following:
In Control Panel -> Network Connections -> Properties of the adapter, Configure-button, Advanced-tab:
"Network Address" had a default setting of "Not present".
Setting a bogus MAC-address to that field fixed the problem.
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