SOLVED: Weird DNS problem: some devices work some do not

akreaxun
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SOLVED: Weird DNS problem: some devices work some do not

Postby akreaxun » Mon Aug 03, 2015 12:41 am

Hi

I recently set up my Amahi 7 using qemu-kvm instead of virtualbox (crash problems). Ever since I use qemu-kvm as the virtualization platform the server never crashed again :-). That solved another really strange problem appeared: some devices cannot connect to the internet because of DNS problems.

Situation in detail:
  • Most devices work perfectly fine with the server. No issues at all. Those are: All other computers, low-end Samsung phones, iPhones.
    Devices that do not work: Samsung 5s mini, Sony TV's
What I figured with the non working devices:
  • DHCP IP lease works. Where testable ping works.
    Connection to the internet fails when using URL's.
Work around:
  • Setting static IP on the "non-working" devices and appointing 8.8.8.8 as the designated DNS solves the problem.
The above solution is a work around and not really satisfactory. Any ideas why there is such a weird behaviour?

rgds
Akrea

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bigfoot65
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Re: Weird DNS problem: some devices work some do not

Postby bigfoot65 » Mon Aug 03, 2015 12:50 pm

Did you disable DHCP on the router and/or VM?

Also have you tried setting static IP addresses for the devices in the HDA dashboard?

Seems like there is a conflict with where DHCP IP addresses are coming for your network.
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akreaxun
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Re: Weird DNS problem: some devices work some do not

Postby akreaxun » Tue Aug 04, 2015 2:50 am

Did you disable DHCP on the router and/or VM?
Is that dnsmasq.conf related to Amahi functionality in any way or can I just "turn it off"? Do you have any experience with it?
Also have you tried setting static IP addresses for the devices in the HDA dashboard?
  • nope
I would love to keep it dynamic as I do have guests once in a while and it should work without additional work with every new device.

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bigfoot65
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Re: Weird DNS problem: some devices work some do not

Postby bigfoot65 » Tue Aug 04, 2015 12:43 pm

Is that dnsmasq.conf related to Amahi functionality in any way or can I just "turn it off"? Do you have any experience with it?
Yes it is what support the DHCP and DNS servers. Turning it off completely would be bad.

Have you checked out the Amahi Virtualized in the wiki? While it should run in a VM just fine, it's primarily designed to run on a single machine as a stand alone.
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akreaxun
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Re: DNS does not work

Postby akreaxun » Thu Aug 06, 2015 5:03 am

Thanks for the info. I have invested another half a day to work on the problem. Unfortunately, without success.

Have you checked out the Amahi Virtualized in the wiki? While it should run in a VM just fine, it's primarily designed to run on a single machine as a stand alone.
Yes I did.

Yet, I can give some more details:
  • By now only my dad's mac is able to work without static IP assignment and DNS 8.8.8.8
  • I went through the network trouble shooting and I got stuck at point 2.3
  • I did check the firewall (disabled) and iptables (no rules, everything ACCEPT) on the host system
  • My /etc/network/interfaces looks like this

    Code: Select all

    # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback # Built in Ethernet auto eth0 iface eth0 inet manual # Bridge auto br0 iface br0 inet static address 192.168.0.10 network 192.168.0.0 netmask 255.255.255.0 broadcast 192.168.0.255 gateway 192.168.0.1 dns-nameservers 192.168.0.10 dns-search amahi.net bridge_ports eth0 bridge_stp off bridge_fd 0 bridge_maxwait 0
  • and if it helps: in the virtmanager the source of Virtual Network Interface is Host device vnet0 (Bridge 'br0') and the device model is vitrio
  • The ifconfig output on the host looks as follows:

    Code: Select all

    br0 Link encap:Ethernet HWaddr yy:yy:yy:yy:yy:yy inet addr:192.168.0.10 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: vvvv::vvvv:vvvv:vvvv:vvvv/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:67903 errors:0 dropped:0 overruns:0 frame:0 TX packets:154651 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:5803618 (5.8 MB) TX bytes:345973238 (345.9 MB) eth0 Link encap:Ethernet HWaddr yy:yy:yy:yy:yy:yy UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:68772 errors:0 dropped:0 overruns:0 frame:0 TX packets:268985 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:6864038 (6.8 MB) TX bytes:353552708 (353.5 MB) eth1 Link encap:Ethernet HWaddr aa:aa:aa:aa:aa:aa inet addr:192.168.0.125 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: vvvv::0vvv:vvvv:vvvv:vvvv/64/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:550 errors:0 dropped:0 overruns:0 frame:0 TX packets:67 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:80275 (80.2 KB) TX bytes:14599 (14.5 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:11966 errors:0 dropped:0 overruns:0 frame:0 TX packets:11966 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:820957 (820.9 KB) TX bytes:820957 (820.9 KB) vnet0 Link encap:Ethernet HWaddr zz:zz:zz:zz:zz:zz inet6 addr: vvvv::2vvv:vvvv:vvvv:vvvv/64/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1095 errors:0 dropped:0 overruns:0 frame:0 TX packets:1437 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:500 RX bytes:105672 (105.6 KB) TX bytes:210183 (210.1 KB)
Any help or hint is appreciated

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bigfoot65
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Re: Weird DNS problem: some devices work some do not

Postby bigfoot65 » Thu Aug 06, 2015 1:06 pm

I do not see /etc/network/interfaces in Amahi 7. Is this from the HDA or the host?

Was this a default Amahi 7 install or did you make modifications?

I have run serveral Amahi 7 installs with Proxmox VE and have not experienced any of this issues. It could be something quirky with qemu-kvm that needs set differently.
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akreaxun
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Re: Weird DNS problem: some devices work some do not

Postby akreaxun » Thu Aug 06, 2015 11:17 pm

Please apologize. Those parameters are from my host system.

On my guest system (Amahi 7) I did not touch a thing. How do I check system settings on a headless fedora? I wasn't able to find a command like 'ifconfig' in fedora (seems to be an easy task, yet I cannot manage to find something).

If i can get it up and running I will write a wiki article about it!

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bigfoot65
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Re: Weird DNS problem: some devices work some do not

Postby bigfoot65 » Fri Aug 07, 2015 9:05 am

You can also try the following:

Code: Select all

ip address
You have to install the net-tools package to use ifconfig.

Code: Select all

yum install net-tools
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akreaxun
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Re: Weird DNS problem: some devices work some do not

Postby akreaxun » Sat Aug 08, 2015 3:59 am

Thanks for the hint the output on the guest system does look OK - according to my humble knowledge:

Code: Select all

[root@localhost sbin]# ip address 1: lo:<LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue pfifo_fast state UP group defailt qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forerver inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 25:54:00:f2:ee:63 brd ff:ff:ff:ff:ff:ff inet 192.168.0.10/24 brd 192.168.0.255 scope global eth0 valid_lft forever preferred_lft forerver inet6 ip:ad:dr:es:sI:p6/64 scope link valid_lft forever preferred_lft forerver [root@localhost sbin]#
I also have experienced really weird behaviour: right now on my personal computer I can work with all dynamic. Yesterday I couldn't. My TV worked yesterday morning without giving fixed IP. In the afternoon it didn't... It is so WEIRD...!

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bigfoot65
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Re: Weird DNS problem: some devices work some do not

Postby bigfoot65 » Sat Aug 08, 2015 6:37 am

Those symptoms allude to there being two DNS servers running on the network. You can only use one for clients. The primary and secondary DNS server IP addresses must be the same if you are using the HDA as one.

Does that make sense?
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