Re: [Vserver] using djbdns (tinydns & dnscache) from within vserver

From: Herbert Poetzl <herbert_at_13thfloor.at>
Date: Thu 13 Apr 2006 - 19:01:33 BST
Message-ID: <20060413180132.GG6663@MAIL.13thfloor.at>

On Thu, Apr 13, 2006 at 10:14:32AM +0200, Benedict Verheyen wrote:
> Hi,
>
> > you could alternatively use the 'plain' init style
> > and have a real init inside the guest, just as on
> > uml :)
>
> Herbert, would using the plain init style have advantages over what
> i'm doing now?
>
> >> Even from within the vserver doing for instance a dnsip doesn't work.
> >
> > how does it fail?
>
> As for the dnsip failing, it doesn't do anything as in not returning a
> value. When it works, it immediately returns the correct value.
>
> >> ccapabilities
> >> icmp
> >> ping
> > those are synonyms, so one of them should
> > be enough, IIRC raw_icmp
>
> i tried specifying the raw_icmp option in the file ccapabilities and
> this is what i got:
> ===========================
> Unknown ccap 'raw_icmp'

what tools are you using? (probably not 0.30.210)

> An error occured while executing the vserver startup sequence; when
> there are no other messages, it is very likely that the init-script
> (/etc/init.d/rc 2) failed.
>
> Common causes are:
> * /etc/rc.d/rc on Fedora Core 1 and RH9 fails always; the 'apt-rpm' build
> method knows how to deal with this, but on existing installations,
> appending 'true' to this file will help.
>
>
> Failed to start vserver 'thor'
> ===========================
>
> If i remove it then it works again.
>
> > probably the only thing really required to be changed
> > is the way you handle the networking, aside from that
> > djbdns should not have any issues, maybe you can
> > elaborate a little on your network setup, and how
> > you test?
>
> (ipconfig & route are way below)
> As for what kind of error, well it doesn't actually give a certain
> error but pinging the hosts or doing an dnsipq on a machine in the dns
> records doesn't work. After further testing, I really think it has to
> do with networking as you say.
>
> Some more about my network:
> Since i used to run 4 uml's, i wanted to ease the way i did networking and
> configured a bridge (br0) and on that bridge 4 tap devices that my uml's
> plugged into. Worked great.
>
> I no longer use the 4 uml's as they are now converted to vservers but the
> bridging is still on and i want to keep it that way because i might use
> the uml's to experiment (as in try things out and destroy it in the
> process :)).

you do not need bridging for the vservers, as they
already share the interface on the host

> Now, sometimes when i start the vserver, the dns stuff works and
> sometimes it doesn't. Very weird. I have no clue on how i can track
> it. Nothing logged in my iptabels (i get a log when a packet is
> dropped or rejected) and i have no firewalling on the bridge.
>
> For instance, sometimes when i start the vserver, when exim comes up,
> it takes a looong time to start. It show this message "Starting MTA: "
> and then takes several minutes to go to the next program that needs to
> be started.
> I think this is because of a dns problem, in other words djbdns that
> isn't capable of doing what it needs to do.

yes dns timeouts are often a reason for unexpected
delays (up to 30 seconds sometimes)

> Then when i enter the vserver, none of the dns utilities work.
>
> I then close the vserver and restart it then and sometimes it then works.
> Other times i need to restart it several times and can't get it to work.
> Very strange.

maybe you should check /etc/resolv.conf and/or
/etc/nsswitch.conf (or at least provide them)

> Last test i did was bringing the uml and the vserver back on but then use a
> different ip (/etc/vserver/thor/interfaces/0/ip) for the vserver.
> Previously i always shut down the uml and use the same ip and name for the
> vserver. Now i changed these settings.
> I changed these to "thor2":
> /etc/vservers/thor/uts/nodename
> /etc/vservers/thor/name
>
> I also changed the /etc/resolv.conf in this vserver to this:
> domain xyz
> nameserver 192.168.1.25
> nameserver 127.0.0.1

you definitely don't want to ask 127.0.0.1 here

> where 192.168.1.25 is the vservers own ip adres (the new one, old one is
> .20) Then i restarted the vserver 5 times and all 5 times dns seems to
> work like it should.
>
> Thanks,
> Benedict
>
> =========================================================================
> My wireless router has the ip 192.168.0.1
> The wireless bridge attached to eth0 has ip 192.168.0.4
> eth0 of the host has ip 192.168.0.2
> eth1 of the host has ip 192.168.1.1
> (bridge br0 gets this ip when i start teh bridging utils)
> The uml with djbdns has ip 192.168.1.20 and the vserver had this ip too
> as i never started them both at the same time.
> When i did so i changed the ip of the vserver to 192.168.1.25
>
> IFCONFIG HOST
> =============
> br0 Link encap:Ethernet HWaddr 00:10:B5:40:DD:EE
> inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:2857 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:291940 (285.0 KiB) TX bytes:0 (0.0 b)
>
> eth0 Link encap:Ethernet HWaddr 00:10:B5:40:DE:14
> inet addr:192.168.0.2 Bcast:192.168.0.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:64372 errors:0 dropped:0 overruns:0 frame:0
> TX packets:68799 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:41328067 (39.4 MiB) TX bytes:7599446 (7.2 MiB)
> Interrupt:10 Base address:0x9400
>
> eth1 Link encap:Ethernet HWaddr 00:10:B5:40:DD:EE
> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
> RX packets:21119 errors:0 dropped:0 overruns:0 frame:0
> TX packets:17425 errors:0 dropped:0 overruns:0 carrier:0
> collisions:36 txqueuelen:1000
> RX bytes:1956692 (1.8 MiB) TX bytes:17260364 (16.4 MiB)
> Interrupt:11 Base address:0x9000
>
> eth0:frey Link encap:Ethernet HWaddr 00:10:B5:40:DE:14
> inet addr:192.168.1.22 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> Interrupt:10 Base address:0x9400
>
> eth0:loki Link encap:Ethernet HWaddr 00:10:B5:40:DE:14
> inet addr:192.168.1.21 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> Interrupt:10 Base address:0x9400
>
> eth0:njor Link encap:Ethernet HWaddr 00:10:B5:40:DE:14
> inet addr:192.168.1.23 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> Interrupt:10 Base address:0x9400
>
> eth0:thor Link encap:Ethernet HWaddr 00:10:B5:40:DE:14
> inet addr:192.168.1.25 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> Interrupt:10 Base address:0x9400
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:130487 errors:0 dropped:0 overruns:0 frame:0
> TX packets:130487 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:38848193 (37.0 MiB) TX bytes:38848193 (37.0 MiB)
>
> tap0 Link encap:Ethernet HWaddr E6:C1:AE:C7:F0:BE
> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:436 errors:0 dropped:2421 overruns:0 carrier:0
> collisions:0 txqueuelen:500
> RX bytes:0 (0.0 b) TX bytes:68855 (67.2 KiB)
>
> tap1 Link encap:Ethernet HWaddr DA:2C:22:1B:B5:B0
> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:2857 overruns:0 carrier:0
> collisions:0 txqueuelen:500
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
>
> tap2 Link encap:Ethernet HWaddr 32:AC:ED:CC:CB:E6
> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:2857 overruns:0 carrier:0
> collisions:0 txqueuelen:500
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
>
> tap3 Link encap:Ethernet HWaddr 76:1D:3F:12:F4:E6
> UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1
> RX packets:0 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:2857 overruns:0 carrier:0
> collisions:0 txqueuelen:500
> RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)
>
> IFCONFIG UML
> ============
> eth0 Link encap:Ethernet HWaddr FE:FD:C0:A8:01:14
> inet addr:192.168.1.20 Bcast:192.168.1.255 Mask:255.255.255.0
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
> RX packets:442 errors:0 dropped:0 overruns:0 frame:0
> TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:1000
> RX bytes:63969 (62.4 KiB) TX bytes:0 (0.0 b)
> Interrupt:5
>
> lo Link encap:Local Loopback
> inet addr:127.0.0.1 Mask:255.0.0.0
> UP LOOPBACK RUNNING MTU:16436 Metric:1
> RX packets:1036 errors:0 dropped:0 overruns:0 frame:0
> TX packets:1036 errors:0 dropped:0 overruns:0 carrier:0
> collisions:0 txqueuelen:0
> RX bytes:106880 (104.3 KiB) TX bytes:106880 (104.3 KiB)
>
> ROUTE HOST
> ==========
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use Iface
> 192.168.0.1 * 255.255.255.255 UH 0 0 0 eth0
> 192.168.0.4 * 255.255.255.255 UH 0 0 0 eth0
> 192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
> 192.168.1.0 * 255.255.255.0 U 0 0 0 br0
> 192.168.0.0 * 255.255.255.0 U 0 0 0 eth0
> default 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
>
>
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Received on Thu Apr 13 19:01:59 2006

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