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Re: [Xen-users] Simple networking problem - DNS

Hi, yeah I tried that unsuccessfully, but you never know it might work for you :).

I get the feeling it's something (even) more fundamental and simple. I believe it is xen related though and something to do with the way the bridge is set up as that appears to be the big network change that occurs when xend starts.

Damon Brown wrote:
Im interested to see, when I get to the test office if I turn iptables off for Dom0 and DomU ..... you may have already tried that but ... maybe its looking me in the face .... :)
-Damon

On 5/23/06, *Julius Spencer* <julius@xxxxxxxxx <mailto:julius@xxxxxxxxx>> wrote:

    I'm using the exact same scenario (CentOS 4.3 with a source compile of
    xen 3.0.2-2). Perhaps it is CentOS related (or the way I have
    compiled it).

    You may find that the DNS dies if you don't do any DNS requests for a
    few minutes before bringing up your domU. I thought it was when I
    brought up the domU but tried just leaving it for a while. It's like DN
    resolution works, then xend starts, DN resolution works a bit longer,
    then stops working.

    Thanks for the reply. I've kept it pretty simple and understand the
    networking well enough to be pretty stumped. Good to hear what you
    find out.

    Cheers,
    Julius.

    Damon Brown wrote:
     > Thats interesting, I have the same issues ..... right when I
    brought up
     > the DomU (which is just a clone of dom0) my DNS wouldnt resolve
     > anylonger.  I was planning on trying to work through it tonight.
     >
     > Im using CentOS 4.3 with a source compile of xen 3.0.2-2
     >
     > On 5/22/06, *Julius Spencer* <julius@xxxxxxxxx
    <mailto:julius@xxxxxxxxx>
     > <mailto: julius@xxxxxxxxx <mailto:julius@xxxxxxxxx>>> wrote:
     >
     >     Hi,
     >
     >     I have spent a fair amount of time trying to solve this
    problem and
     >     tried things like disabling checksums etc.
     >
     >     The problem is like this:
     >     1. I boot my dom0 without xend running and I can resolve and ping
     >     google.
     >     2. I start xend (without and domU domains up) and after a
    while I can no
     >     longer resolve domain names, but I can ping the public IP
    addresses.
     >     3. I start up a domU (xm create -c xyz) and I have the same
    issue there
     >     too (not surprising as it is using the same bridge).
     >
     >     The following is a list of info after step 3 for the dom0 and
    domU both
     >     of which can ping public IP addresses but not resolve domain
    names. The
     >     tcpdump is being run on dom0.
     >
     >
     >     Any ideas? It seems like it must be a pretty specific
    configuration
     >     change.
     >
     >     Cheers,
     >     Julius.
     >
     >     ##DNS Request from dom0
     >     tcpdump: listening on eth0, link-type EN10MB (Ethernet),
    capture size 96
     >     bytes
     >     15:25: 40.336919 IP (tos 0x0, ttl  64, id 33990, offset 0,
    flags [DF],
     >     proto 17, length: 56) 192.168.1.201.32774 >
    192.168.1.1.domain: [udp sum
     >     ok]  46934+ A? google.com <http://google.com>
    <http://google.com>. (28)
     >     15:25:40.336966 IP (tos 0x0, ttl  64, id 33990, offset 0,
    flags [DF],
     >     proto 17, length: 56) 192.168.1.201.32774 >
    192.168.1.1.domain : [udp sum
     >     ok]  46934+ A? google.com <http://google.com>
    <http://google.com>. (28)
     >
     >     ##DNS Request from domU
     >     15:25:51.968703 arp who-has 192.168.1.1 <http://192.168.1.1>
    <http://192.168.1.1> tell
     >     192.168.1.231 <http://192.168.1.231> <http://192.168.1.231
    <http://192.168.1.231>>
     >     15:25:51.988626 arp who-has 192.168.1.231
    <http://192.168.1.231> <http://192.168.1.231>
     >     tell 192.168.1.201 <http://192.168.1.201> <http://192.168.1.201>
     >     15:25:51.988720 arp reply 192.168.1.231
    <http://192.168.1.231> <http://192.168.1.231> is-at
     >     00:16:3e:00:00:03
     >     15:25:51.988737 IP (tos 0xc0, ttl  64, id 62783, offset 0, flags
     >     [none],
     >     proto 1, length: 84) 192.168.1.201 <http://192.168.1.201> <
    http://192.168.1.201> >
     >     192.168.1.231 <http://192.168.1.231> <http://192.168.1.231>:
    icmp 64: host
     >     192.168.1.1 <http://192.168.1.1> <http://192.168.1.1>
    unreachable - admin prohibited for
     >     IP (tos 0x0, ttl  64, id
     >     64204, offset 0, flags [DF], proto 17, length: 56)
    192.168.1.231.32769 >
     >     192.168.1.1.domain:  16734+[|domain]
     >     15:25:51.988880 IP (tos 0xc0, ttl  64, id 62784, offset 0,
    flags [none],
     >     proto 1, length: 84) 192.168.1.201 <http://192.168.1.201> <
    http://192.168.1.201> >
     >     192.168.1.231 <http://192.168.1.231> <http://192.168.1.231>:
    icmp 64: host
     >     192.168.1.1 <http://192.168.1.1> <http://192.168.1.1>
    unreachable - admin prohibited for
     >     IP (tos 0x0, ttl  64, id
     >     64210, offset 0, flags [DF], proto 17, length: 56)
    192.168.1.231.32769 >
     >     192.168.1.1.domain:  16734+[|domain]
     >
     >     ##NTP Reuqest from dom0
     >     15:25:49.518708 IP (tos 0x10, ttl  64, id 113, offset 0,
    flags [DF],
     >     proto 17, length: 76) 192.168.1.201.ntp > 194.100.206.70.ntp
    : [udp sum
     >     ok] NTPv4, length 48
     >              Client, Leap indicator:  (0), Stratum 3, poll 7s,
    precision -20
     >              Root Delay: 0.414093, Root dispersion: 0.031051 ,
    Reference-ID:
     >     194.100.206.70 <http://194.100.206.70> <http://194.100.206.70>
     >                Reference Timestamp:  3357343418.923047999
    (2006/05/23
     >     15:23:38)
     >                Originator Timestamp: 3357343418.718721999 (2006/05/23
     >     15:23:38)
     >                Receive Timestamp:    3357343418.923047999 (2006/05/23
     >     15:23:38)
     >                Transmit Timestamp:   3357343549.518689999 (2006/05/23
     >     15:25:49)
     >                  Originator - Receive Timestamp:  +0.204326000
     >                  Originator - Transmit Timestamp: +130.799968000
     >     15:25:49.920925 IP (tos 0x0, ttl  39, id 0, offset 0, flags
    [DF], proto
     >     17, length: 76) 194.100.206.70.ntp > 192.168.1.201.ntp: [udp
    sum ok]
     >     NTPv4, length 48
     >              Server, Leap indicator:  (0), Stratum 2, poll 7s,
    precision
     >     -16
     >              Root Delay: 0.011306, Root dispersion: 0.019927,
    Reference-ID:
     >     192.36.144.22 <http://192.36.144.22> <http://192.36.144.22 >
     >                Reference Timestamp:  3357343336.749644999 (2006/05/23
     >     15:22:16)
     >                Originator Timestamp: 3357343549.518689999 (2006/05/23
     >     15:25:49)
     >                Receive Timestamp:     3357343549.716807999
    (2006/05/23
     >     15:25:49)
     >                Transmit Timestamp:   3357343549.716845999 (2006/05/23
     >     15:25:49)
     >                  Originator - Receive Timestamp:  +0.198118000
     >                  Originator - Transmit Timestamp: +0.198156000
     >
     >     #####ifconfig dom0
     >     eth0      Link encap:Ethernet  HWaddr 00:11:25:A4:6C:4B
     >                inet addr: 192.168.1.201 <http://192.168.1.201>
    <http://192.168.1.201>  Bcast:
     >     192.168.1.255 <http://192.168.1.255>
    <http://192.168.1.255>  Mask: 255.255.255.0 <http://255.255.255.0>
     >     <http://255.255.255.0>
     >                UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
     >                RX packets:425 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:1327 errors:0 dropped:0 overruns:0
    carrier:0
     >                collisions:0 txqueuelen:0
     >                RX bytes:224495 (219.2 KiB)  TX bytes:126651
    (123.6 KiB)
     >
     >     lo        Link encap:Local Loopback
     >                inet addr:127.0.0.1 <http://127.0.0.1>
    <http://127.0.0.1>  Mask:255.0.0.0 <http://255.0.0.0>
     >     < http://255.0.0.0>
     >                UP LOOPBACK RUNNING  MTU:16436  Metric:1
     >                RX packets:963 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:963 errors:0 dropped:0 overruns:0
    carrier:0
     >                collisions:0 txqueuelen:0
     >                RX bytes:98272 (95.9 KiB)  TX bytes:98272 (95.9 KiB)
     >
     >     peth0     Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
     >                UP BROADCAST RUNNING NOARP
    MULTICAST  MTU:1500  Metric:1
     >                RX packets:1029 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:403 errors:0 dropped:0 overruns:0 carrier:0
     >                collisions:0 txqueuelen:1000
     >                RX bytes:431691 ( 421.5 KiB)  TX bytes:47343 (46.2
    KiB)
     >                Interrupt:16
     >
     >     vif0.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
     >                UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
     >                RX packets:1327 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:425 errors:0 dropped:0 overruns:0 carrier:0
     >                collisions:0 txqueuelen:0
     >                RX bytes:126651 ( 123.6 KiB)  TX bytes:224495 (
    219.2 KiB)
     >
     >     vif1.0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
     >                UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
     >                RX packets:74 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:84 errors:0 dropped:22 overruns:0 carrier:0
     >                collisions:0 txqueuelen:0
     >                RX bytes:4764 (4.6 KiB)  TX bytes:6566 (6.4 KiB)
     >
     >     xenbr0    Link encap:Ethernet  HWaddr FE:FF:FF:FF:FF:FF
     >                UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
     >                RX packets:668 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
     >                collisions:0 txqueuelen:0
     >                RX bytes:195790 (191.2 KiB)  TX bytes:0 ( 0.0 b)
     >
     >     ###ifconfig domU
     >     eth0      Link encap:Ethernet  HWaddr 00:16:3E:00:00:03
     >                inet addr:192.168.1.231 <http://192.168.1.231>
     >     <http://192.168.1.231>  Bcast:192.168.1.255
    <http://192.168.1.255>
     >     < http://192.168.1.255>  Mask: 255.255.255.0
    <http://255.255.255.0> <http://255.255.255.0>
     >                inet6 addr: fe80::216:3eff:fe00:3/64 Scope:Link
     >                UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
     >                RX packets:84 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:74 errors:0 dropped:0 overruns:0 carrier:0
     >                collisions:0 txqueuelen:1000
     >                RX bytes:6566 (6.4 KiB)  TX bytes:4764 (4.6 KiB)
     >
     >     lo        Link encap:Local Loopback
     >                inet addr: 127.0.0.1 <http://127.0.0.1>
    <http://127.0.0.1>  Mask:255.0.0.0 <http://255.0.0.0>
     >     <http://255.0.0.0>
     >                inet6 addr: ::1/128 Scope:Host
     >                UP LOOPBACK RUNNING  MTU:16436  Metric:1
     >                RX packets:8 errors:0 dropped:0 overruns:0 frame:0
     >                TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
     >                collisions:0 txqueuelen:0
     >                RX bytes:560 (560.0 b)  TX bytes:560 (560.0 b)
     >
     >     _______________________________________________
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    <mailto:Xen-users@xxxxxxxxxxxxxxxxxxx>
    <mailto:Xen-users@xxxxxxxxxxxxxxxxxxx
    <mailto:Xen-users@xxxxxxxxxxxxxxxxxxx>>
     >     http://lists.xensource.com/xen-users
    <http://lists.xensource.com/xen-users>
     >
     >
     >
     >
     > --
     > Damon Brown
     > Web Application Developer and Consultant
     > e-mail: damon@xxxxxxxxxxxxxx <mailto:damon@xxxxxxxxxxxxxx>
    <mailto: damon@xxxxxxxxxxxxxx <mailto:damon@xxxxxxxxxxxxxx>>
     >
     >
     >
    ------------------------------------------------------------------------
     >
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--
Damon Brown
Web Application Developer and Consultant
e-mail: damon@xxxxxxxxxxxxxx <mailto:damon@xxxxxxxxxxxxxx>

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