[Dnsmasq-discuss] Windows ipv6 hostname

Markus Hartung mail at hartmark.se
Thu Dec 22 10:24:53 GMT 2016


On 2016-12-21 14:08, Michael Stilkerich wrote:
> Well, dnsmasq needs to get the hostname to assign to a machine from 
> someplace. I don't know
> all the possible places (search the manual page for that), but I can 
> think of:
>
>   1) Dnsmasq configuration (dhcp-host options)
>   2) /etc/ethers if enabled
>   3) suggested with the DHCPv4 request by the client
>
> I think Windows 10 should suggest a hostname (3), at least it seems to 
> do for me. I have manually assigned
> a hostname on the Windows computer, and dnsmasq knows and assigns it.

On 2016-12-20 12:53, Pali Rohár wrote:
> Another option is to stop using SLAAC and start using DHCPv6 where you
> have full control of assigned IPv6 addresses.
>
> Such feature like host will "randomly" chose address is unsuitable for
> setup when you need to have control of which address is assigned to
> which device (e.g in this setup when you want to assign AAAA record).
I have managed to get DHCPv6 working now, I thought that windows 10 
didn't have any support for it. It turned out that my ufw on my ubuntu 
server were blocking the DHCPv6. I was in my simple mind just assuming 
that DHCP and DHCPv6 used same ports

Still no hostname in the lease-file. However, I tried creating a virtual 
win10 host and it seems to correctly set the hostname.

$ cat /var/lib/misc/dnsmasq.leases
1482450696 3e:fa:72:5b:c7:02 192.168.1.184 * 01:3e:fa:72:5b:c7:02
1482454218 08:00:27:60:fb:f2 192.168.1.108 budweiser 01:08:00:27:60:fb:f2
1482454219 34078759 2001:470:28:6ac::b8c2 budweiser 
00:01:00:01:1f:6b:f9:80:08:00:27:60:fb:f2
1482454045 171899506 2001:470:28:6ac::e82c * 00:03:00:01:3e:fa:72:5b:c7:02

Note that the host budweiser correcly gets a host entry in the file. And 
ping:ing the hostname on ipv4 and ipv6 yields the correct ip-address.

Been doing some wireshark-ing and found this request on the working host:

Frame 1998: 210 bytes on wire (1680 bits), 210 bytes captured (1680 
bits) on interface 0
Ethernet II, Src: PcsSyste_60:fb:f2 (08:00:27:60:fb:f2), Dst: 
IPv6mcast_01:00:02 (33:33:00:01:00:02)
Internet Protocol Version 6, Src: fe80::a00:27ff:fe60:fbf2, Dst: ff02::1:2
User Datagram Protocol, Src Port: 546, Dst Port: 547
DHCPv6
     Message type: Request (3)
     Transaction ID: 0xe6d3a2
     Elapsed time
     Client Identifier
     Server Identifier
     Identity Association for Non-temporary Address
     Fully Qualified Domain Name
         Option: Fully Qualified Domain Name (39)
         Length: 24
         Value: 000962756477656973657208686172746d61726b02736500
         0000 0... = Reserved: 0x00
         .... .0.. = N bit: Server should perform DNS updates
         .... ..0. = O bit: Server has not overridden client's S bit 
preference
         .... ...0 = S bit: Server should not perform forward DNS updates
         Client FQDN: budweiser.hartmark.se
     Vendor Class
         Option: Vendor Class (16)
         Length: 14
         Value: 0000013700084d53465420352e30
         Enterprise ID: Microsoft (311)
         vendor-class-data: MSFT 5.0
     Option Request
         Option: Option Request (6)
         Length: 8
         Value: 0011001700180027
         Requested Option code: Vendor-specific Information (17)
         Requested Option code: DNS recursive name server (23)
         Requested Option code: Domain Search List (24)
         Requested Option code: Fully Qualified Domain Name (39)

and this is the request for the broken host:
Frame 786: 160 bytes on wire (1280 bits), 160 bytes captured (1280 bits) 
on interface 0
Ethernet II, Src: 3e:fa:72:5b:c7:02 (3e:fa:72:5b:c7:02), Dst: 
IPv6mcast_01:00:02 (33:33:00:01:00:02)
Internet Protocol Version 6, Src: fe80::3cfa:72ff:fe5b:c702, Dst: ff02::1:2
User Datagram Protocol, Src Port: 546, Dst Port: 547
DHCPv6
     Message type: Request (3)
     Transaction ID: 0x83e70d
     Elapsed time
     Client Identifier
     Server Identifier
     Identity Association for Non-temporary Address
     Option Request
         Option: Option Request (6)
         Length: 8
         Value: 0011001700180027
         Requested Option code: Vendor-specific Information (17)
         Requested Option code: DNS recursive name server (23)
         Requested Option code: Domain Search List (24)
         Requested Option code: Fully Qualified Domain Name (39)

however it seems it tries to update its dns record like this:
973    84.385064    192.168.1.184    195.178.160.145    DNS 200    
Dynamic update 0xf052 SOA hartmark.se CNAME AAAA A AAAA 
2001:470:28:6ac::e834 AAAA 2001:470:28:6ac:3cfa:72ff:fe5b:c702 A 
192.168.1.184

974    84.389532    195.178.160.145    192.168.1.184    DNS 200    
Dynamic update response 0xf052 Not implemented SOA hartmark.se CNAME 
AAAA A AAAA 2001:470:28:6ac::e834 AAAA 
2001:470:28:6ac:3cfa:72ff:fe5b:c702 A 192.168.1.184

I need to do some more digging, but perhaps someone knows why the hosts 
tries to do differently. And is the dynamic update dns some microsoft 
dns server thingy?

Best regards,
Markus



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