Weird DNS issue with Android Wifi Calling

cmb · Mar 29, 2016, 5:24 AM

I assumed you were using Google's DNS given the comment re: the MAC. Source of the problem still sounds the same, just on a diff IP. If the DNS server in question is a local IP, then it's that local IP that has the IP conflict.

britcowboy · Mar 29, 2016, 5:53 AM

I feel like I need to explain myself a bit better.

My gateway is pfsense on 10.0.1.19
I have two local DNS servers, both Windows DNS on an active domain which are synced. These are 10.0.1.30 and 10.0.1.22.

These DNS servers both forward to Google DNS, if it can't resolve it.

This has been my setup for months, all my machines work fine, always resolving websites and local services.

The only issue I have noticed is this wifi calling DNS request made by android. While monitoring it with wireshark all over DNS queries were made to 10.0.1.30 with the correct mac address. I downloaded a nslookup tool for Android and when requesting the same host through that the packet was correct and went to the correct DNS server with the correct mac address.

When I said I'm not saying you're incorrect but earlier, I wasn't disputing the MACs only working locally, just the duplicate ips.

I honestly think that this is a bug in Androids implementation of Wifi calling, because my girlfriend iPhone has always consistently worked (with my local DNS servers) with EE Wifi Calling. It's only been my android phone that's had any issues. It seems there's a bug where this one call gets the ip of the DNS server and the mac of the gateway server mixed up and uses the wrong combination. I think this one call is special because it's a core built in service.

I'm really happy to be wrong and to find a solution though. But that's my thinking at the moment. This bug could be easily missed as 90% of home users won't run a local DNS so the DNS MAC will match the gateway MAC.

Here is my ARP cache in pfsense. https://imgur.com/6X6LU5g

Honestly I want to be wrong because an Android bug is going to be a PITA to get fixed. Anyone think I've misunderstood or am wrong?

Cheers

(also sorry for bad spelling, on mobile)

Derelict · Mar 29, 2016, 6:46 AM

Well if your Windows DNS Servers forward to google for global resolution I don't see where pfSense fits into the picture.

MAC addresses really have nothing to do with your problem unless, as has been said, you have an IP address conflict. Just forget about MAC addresses.

It really sounds like you need to realize a DNS strategy, get it working, then make sure all your devices are configured to use it.

Is the working iPhone configured to use the same DNS servers as the broken android phone?

britcowboy · Mar 29, 2016, 12:07 PM

@Derelict:

Well if your Windows DNS Servers forward to google for global resolution I don't see where pfSense fits into the picture.

MAC addresses really have nothing to do with your problem unless, as has been said, you have an IP address conflict. Just forget about MAC addresses.

It really sounds like you need to realize a DNS strategy, get it working, then make sure all your devices are configured to use it.

Is the working iPhone configured to use the same DNS servers as the broken android phone?

Yes, the iPhone has 10.0.1.30 and 10.0.1.22 as DNS servers and works perfectly, as does every other computer on the network. The only reason I bring up mac addresses is because the broken DNS packet as seen via wireshark has the wrong mac address so the DNS server isn't recieving the packet (i'm right in the assumption that no matter what the ip address is, NIC will ignore packets sent to it with a different mac address aren't I?)

johnpoz · Mar 29, 2016, 12:11 PM

"NIC will ignore packets sent to it with a different mac address aren't I?)"

What?? Post up this sniff showing what you think is a wrong mac..

In your sniff there was NO answer to your queries.. No shit if your dns does not answer you can not look up stuff..

britcowboy · Mar 29, 2016, 12:38 PM

@johnpoz:

"NIC will ignore packets sent to it with a different mac address aren't I?)"

What?? Post up this sniff showing what you think is a wrong mac..

In your sniff there was NO answer to your queries.. No shit if your dns does not answer you can not look up stuff..

Ive attached the traces

In the Onlythatdnsrequestbeingignored.png you can see that the DNS server is happily responding to every other DNS request coming from the android phone.

The workingdns image shows a packet being sent to 10.0.1.30 with its correct mac address, so the dns server responds.

The brokendns image shows the only packet thats broken. The only difference is the MAC address (which is my gateway not the dns server).

I put Microsoft DNS in debugging mode, which logs all requests, and it never even sees the broken DNS packet (because, i assume, the NIC ignores it as it has the incorrect MAC address)

See what I mean? This seems like unusual behaviour from my android device.

johnpoz · Mar 29, 2016, 12:46 PM

What device do you own that is this mac?

6C:0B:84:08:67:34 I show it as Universal Global Scientific Industrial Co.,Ltd.

Clearly if your windows dns server is at 00:15:5d:01:f4:01 then no shit another box that is not running dns is not going to answer. You most likely have something that has the same IP 10.0.1.30 as your windows dns server is the most likely issue.

Is it this company http://www.usish.com/english/overview.asp look up what they make and what device you have of theirs.

britcowboy · Mar 29, 2016, 1:03 PM

@johnpoz:

What device do you own that is this mac?

6C:0B:84:08:67:34 I show it as Universal Global Scientific Industrial Co.,Ltd.

Clearly if your windows dns server is at 00:15:5d:01:f4:01 then no shit another box that is not running dns is not going to answer. You most likely have something that has the same IP 10.0.1.30 as your windows dns server is the most likely issue.

Is it this company http://www.usish.com/english/overview.asp look up what they make and what device you have of theirs.

No, the windows box is at 6C:0B:84:08:67:34 (10.0.1.30). Thats the mac of the integrated Intel NIC on the motherboard.

The 00:15:5d:01:f4:01 mac address is that of pfsense (gateway) which is running on ip 10.0.1.19.

There is no ip conflict between them, both their IPs are static, and I posted my ARP Cache earlier and no MACs are duplicated.

That's why I'm at a loss

johnpoz · Mar 29, 2016, 2:45 PM

Dude clearly 00:15:5d is a microsoft mac…

MAC Address Details

Company
Microsoft Corporation
Address
Redmond WA 98052-8300
UNITED STATES
Range
00:15:5D:00:00:00 - 00:15:5D:FF:FF:FF
Type
IEEE MA-L

And clearly from your sniff your sending traffic for 10.0.1.30 to that MAC...

if your saying your windows box nic is that global universal company... That what is the microsoft mac device??

Post up your ifconfig from your pfsense box, and y our ipconfig /all from your windows machine running dns..

britcowboy · Mar 29, 2016, 3:19 PM

@johnpoz:

Dude clearly 00:15:5d is a microsoft mac…

MAC Address Details

Company
Microsoft Corporation
Address
Redmond WA 98052-8300
UNITED STATES
Range
00:15:5D:00:00:00 - 00:15:5D:FF:FF:FF
Type
IEEE MA-L

And clearly from your sniff your sending traffic for 10.0.1.30 to that MAC...

if your saying your windows box nic is that global universal company... That what is the microsoft mac device??

Post up your ifconfig from your pfsense box, and y our ipconfig /all from your windows machine running dns..

The reason why pfsense has a microsoft MAC is because it's a VM and that's a software NIC which is teamed with 3 NICS and LACP'ed at the router level. The 10.0.1.30 DNS Server is a physical server. 10.0.1.22 is a VM.

pfsense:

$ ifconfig
pflog0: flags=100 <promisc>metric 0 mtu 33144
pfsync0: flags=0<> metric 0 mtu 1500
	syncpeer: 224.0.0.240 maxupd: 128 defer: on
	syncok: 1
lo0: flags=8049 <up,loopback,running,multicast>metric 0 mtu 16384
	options=600003 <rxcsum,txcsum,rxcsum_ipv6,txcsum_ipv6>inet 127.0.0.1 netmask 0xff000000 
	inet6 ::1 prefixlen 128 
	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3 
	nd6 options=21 <performnud,auto_linklocal>enc0: flags=0<> metric 0 mtu 1536
	nd6 options=21 <performnud,auto_linklocal>hn0: flags=8843 <up,broadcast,running,simplex,multicast>metric 0 mtu 1500
	options=18 <vlan_mtu,vlan_hwtagging>ether 00:15:5d:01:f4:00
	inet6 fe80::215:5dff:fe01:f400%hn0 prefixlen 64 scopeid 0x5 
	nd6 options=21 <performnud,auto_linklocal>hn1: flags=8843 <up,broadcast,running,simplex,multicast>metric 0 mtu 1500
	options=18 <vlan_mtu,vlan_hwtagging>ether 00:15:5d:01:f4:01
	inet6 fe80::215:5dff:fe01:f401%hn1 prefixlen 64 scopeid 0x6 
	inet 10.0.1.19 netmask 0xffffff00 broadcast 10.0.1.255 
	nd6 options=21 <performnud,auto_linklocal>pppoe2: flags=88d1 <up,pointopoint,running,noarp,simplex,multicast>metric 0 mtu 1492
	inet6 fe80::215:5dff:fe01:f400%pppoe2 prefixlen 64 scopeid 0x7 
	inet <<myip>> --> 195.166.130.211 netmask 0xffffffff 
	nd6 options=21 <performnud,auto_linklocal>ovpns1: flags=8051 <up,pointopoint,running,multicast>metric 0 mtu 1500
	<<omitted>>
ovpns2: flags=8051 <up,pointopoint,running,multicast>metric 0 mtu 1500
	<<omitted>>
ovpnc3: flags=8051 <up,pointopoint,running,multicast>metric 0 mtu 1500
	<<omitted>>
ovpnc4: flags=8051 <up,pointopoint,running,multicast>metric 0 mtu 1500
	<<omitted>>
ovpnc5: flags=8051 <up,pointopoint,running,multicast>metric 0 mtu 1500
	<<omitted>></omitted></up,pointopoint,running,multicast></omitted></up,pointopoint,running,multicast></omitted></up,pointopoint,running,multicast></omitted></up,pointopoint,running,multicast></omitted></up,pointopoint,running,multicast></performnud,auto_linklocal></myip></up,pointopoint,running,noarp,simplex,multicast></performnud,auto_linklocal></vlan_mtu,vlan_hwtagging></up,broadcast,running,simplex,multicast></performnud,auto_linklocal></vlan_mtu,vlan_hwtagging></up,broadcast,running,simplex,multicast></performnud,auto_linklocal></performnud,auto_linklocal></rxcsum,txcsum,rxcsum_ipv6,txcsum_ipv6></up,loopback,running,multicast></promisc>

10.0.1.30


C:\Windows\system32>ipconfig /all

Windows IP Configuration

   Host Name . . . . . . . . . . . . : Gibson
   Primary Dns Suffix  . . . . . . . : mydomain.private
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : mydomain.private

Ethernet adapter vEthernet (Internal): (this is a private VM network to some VMs)

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Hyper-V Virtual Ethernet Adapter #2
   Physical Address. . . . . . . . . : 00-15-5D-01-F4-0A
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv4 Address. . . . . . . . . . . : 192.168.0.1(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :
   NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Integrated: (this is a physical onboard NIC just for 10.0.1.30)

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Intel(R) Ethernet Connection I217-LM
   Physical Address. . . . . . . . . : 6C-0B-84-08-67-34
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv4 Address. . . . . . . . . . . : 10.0.1.30(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 10.0.1.19
   DNS Servers . . . . . . . . . . . : 127.0.0.1
                                       10.0.1.22
   NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter isatap.{CD48BF58-A900-4A8C-917E-6E0083ABD4E4}:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.{D7362D7E-EA03-4337-8329-58F19F230FE7}:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

britcowboy · Mar 29, 2016, 3:41 PM

I just tried (for testing purposes, I don't want to keep it like this) switching on the DNS Forwarder on the pfsense box to 10.0.1.30, and then pointing my android phone to 10.0.1.19 (pfsense) and that works perfectly. But obviously this isn't ideal, I don't get why it's querying the windows dns server with the pfsense mac address

johnpoz · Mar 29, 2016, 4:28 PM

So clearly your machine doing the query to 10.0.1.30 thinks that this address is at pfsense MAC.. But that is not what pfsense shows.

Now your saying pfsense is a VM, that uses the same hardware nic as your physical machine nic. So you have a problem in your virtual setup.

Look on your sniffs for when your machine arps for 10.0.1.30.. For some reason it is getting the wrong mac for this.. So you need to figure out why.. You do not have any sort of static arps setup on device doing the queries.

britcowboy · Mar 29, 2016, 4:41 PM

@johnpoz:

So clearly your machine doing the query to 10.0.1.30 thinks that this address is at pfsense MAC.. But that is not what pfsense shows.

Now your saying pfsense is a VM, that uses the same hardware nic as your physical machine nic. So you have a problem in your virtual setup.

Look on your sniffs for when your machine arps for 10.0.1.30.. For some reason it is getting the wrong mac for this.. So you need to figure out why.. You do not have any sort of static arps setup on device doing the queries.

Seems to be fine :/

johnpoz · Mar 29, 2016, 4:58 PM

Yes that arp is fine, what about all the other arps?

Dude if your never seeing arp come back with that mac.. Then how/why would you client send traffic to it.. It would be impossible for that to happen.

That is not a normal arp, that is directed.. A normal arp is to ff:ff:ff:ff:ff:ff

britcowboy · Mar 29, 2016, 4:45 PM

@johnpoz:

Yes that arp is fine, what about all the other arps?

Dude if your never seeing arp come back with that mac.. Then how/why would you client send traffic to it.. It would be impossible for that to happen.

That is not a normal arp, that is directed..

I hear you, but this is why I think it's a bug with Android, because all other DNS requests from android work fine, it's just that one DNS request. I rebooted the phone, connected to wifi, and thats the only ARP I see.

johnpoz · Mar 29, 2016, 4:58 PM

see my edit, that is not a correct arp.. An arp is to all F's