[Openstack] dns issue?

Jorge Luiz Correa correajl at gmail.com
Fri Oct 7 18:30:18 UTC 2011


It seems that configs are OK.

If you use dig from the controller, could resolv names? I'm asking because
can be case that packets arrive from VMs to controller but couldn't go to
Internet.

Another thing you can check. Although the resolv.conf of VMs are set with
10.0.1.1, there are a lot of iptables rules. I was using Cactus and I
noticed that. If you type nova-manage network list you will see the networks
and you can see a DNS collumn. The default was 8.8.4.4 but when I started
instances this values changed to 10.0.2.1 or something like that! My concern
is about what address nova uses to create rules!! Maybe all services are OK
but a wrong iptables rule is dropping packets!

iptables -n -L
iptables -n -L -t nat

Check if you have some rule permitting udp 53 to be forward/accepted (ie,
not dropped).

As a debug option, you can run tcpdump on the controller interface and see
what are happening with the packets.

tcpdump -n -i <interface> port 53

:)

On Fri, Oct 7, 2011 at 2:51 PM, Sharif Islam <islamsh at indiana.edu> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 10/07/2011 01:44 PM, Jorge Luiz Correa wrote:
> > Check if you have a dnsmasq running on host that runs nova-network. It's
> > necessary a DNS service on 10.0.1.1.
> >
> > On the nova-network host:
> >
> > $ ps aux | grep dns
> >
>
> # ps aux|grep dnsmasq
> nobody   11879  0.0  0.0  12872   652 ?        S    10:15   0:01 dnsmasq
> - --strict-order --bind-interfaces --conf-file= --domain=novalocal
> - --pid-file=/local/nova/networks/nova-br100.pid --listen-address=10.0.1.1
> - --except-interface=lo --dhcp-range=10.0.1.2,static,120s
> - --dhcp-lease-max=256
> - --dhcp-hostsfile=/local/nova/networks/nova-br100.conf
> - --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro
> root     11880  0.0  0.0  12872   212 ?        S    10:15   0:00 dnsmasq
> - --strict-order --bind-interfaces --conf-file= --domain=novalocal
> - --pid-file=/local/nova/networks/nova-br100.pid --listen-address=10.0.1.1
> - --except-interface=lo --dhcp-range=10.0.1.2,static,120s
> - --dhcp-lease-max=256
> - --dhcp-hostsfile=/local/nova/networks/nova-br100.conf
> - --dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro
>
>
>
>
>
> >
> > $ netstat -tupan | grep 53
>
> tcp        0      0 10.0.1.1:53                 0.0.0.0:*
>    LISTEN      11879/dnsmasq
> udp        0      0 10.0.1.1:53                 0.0.0.0:*
>                11879/dnsmasq
>
>
> i also tried killall dnsmasq and restarting nova-network. I haven't
> deleting the network and recreating it yet.
>
> route table in the controller:
>
> # route -n
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> 10.0.1.0        0.0.0.0         255.255.255.0   U     0      0        0
> br100
> xxx.xx.xx.xxx   0.0.0.0         255.255.255.0   U     0      0        0
> eth1
> 192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0
> virbr0
> 172.29.200.0    0.0.0.0         255.255.252.0   U     0      0        0
> br100
> 169.254.0.0     0.0.0.0         255.255.0.0     U     1004   0        0
> eth1
> 0.0.0.0         149.165.146.254 0.0.0.0         UG    0      0        0
> eth1
>
>
> - --sharif
>
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-- 
- MSc. Correa, J.L.
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