[Dnsmasq-discuss] Windows Server 2008 R2 issue

[Brian Haley]

Hi,

I'm having trouble getting a Windows Server 2008 R2 virtual machine to get a
lease from dnsmasq running on Ubuntu Linux.  An R1, and any other OS, has no
problems.  The version of dnsmasq is 2.58-3.

My config is as follows:

eth0 - public interface - IP 15.3.2.1 (that's not my real IP)
brx1 - private bridge   - IP 10.13.128.1
vnetX - taps attached to the bridge

Here's the ps output for dnsmasq:

20761 ?        S      0:00 dnsmasq --strict-order --bind-interfaces
--conf-file=/var/lib/nova/networks/dnsmasq.conf --domain=novalocal
--pid-file=/var/lib/nova/networks/nova-brx1.pid --listen-address=10.13.128.1
--except-interface=lo --dhcp-range=10.13.128.2,static,255.255.224.0,900s
--dhcp-lease-max=8192 --dhcp-hostsfile=/var/lib/nova/networks/nova-brx1.conf
--dhcp-script=/usr/bin/nova-dhcpbridge --leasefile-ro

That dnsmasq.conf file just has two srv-host lines for my windows license servers.

Running tcpdump, I see plenty of "good" request/responses, for example, this is
an R1 server:

21:35:18.255923 02:16:3e:2e:e9:b7 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800),
length 342: (tos 0x0, ttl 128, id 1, offset 0, flags [none], proto UDP (17),
length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 02:16:3e:2e:e9:b7,
length 300, xid 0x4a51edc4, secs 1280, Flags [none]
          Client-Ethernet-Address 02:16:3e:2e:e9:b7
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Client-ID Option 61, length 7: ether 02:16:3e:2e:e9:b7
            Hostname Option 12, length 15: "WIN-HRD4U0NMS2R"
            Vendor-Class Option 60, length 8: "MSFT 5.0"
            Parameter-Request Option 55, length 12:
              Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
              Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
              Static-Route, Classless-Static-Route,
Classless-Static-Route-Microsoft, Vendor-Option

21:35:18.256184 02:16:3f:0c:10:0d > 02:16:3e:2e:e9:b7, ethertype IPv4 (0x0800),
length 345: (tos 0x0, ttl 64, id 22748, offset 0, flags [none], proto UDP (17),
length 331)
    10.13.128.1.67 > 10.13.128.217.68: BOOTP/DHCP, Reply, length 303, xid
0x4a51edc4, secs 1280, Flags [none]
          Your-IP 10.13.128.217
          Server-IP 10.13.128.1
          Client-Ethernet-Address 02:16:3e:2e:e9:b7
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Offer
            Server-ID Option 54, length 4: 10.13.128.1
            Lease-Time Option 51, length 4: 900
            RN Option 58, length 4: 450
            RB Option 59, length 4: 787
            Subnet-Mask Option 1, length 4: 255.255.224.0
            BR Option 28, length 4: 10.13.159.255
            Default-Gateway Option 3, length 4: 10.13.128.1
            Domain-Name-Server Option 6, length 4: 10.13.128.1
            Domain-Name Option 15, length 9: "novalocal"

But for the R2 server I see:

21:26:10.522156 02:16:3e:4b:cc:53 > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800),
length 342: (tos 0x0, ttl 128, id 346, offset 0, flags [none], proto UDP (17),
length 328)
    0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 02:16:3e:4b:cc:53,
length 300, xid 0xcc8a146d, secs 6656, Flags [Broadcast]
          Client-Ethernet-Address 02:16:3e:4b:cc:53
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            NOAUTO Option 116, length 1: Y
            Client-ID Option 61, length 7: ether 02:16:3e:4b:cc:53
            Hostname Option 12, length 15: "WIN-OE4E9RLAG6M"
            Vendor-Class Option 60, length 8: "MSFT 5.0"
            Parameter-Request Option 55, length 12:
              Subnet-Mask, Domain-Name, Default-Gateway, Domain-Name-Server
              Netbios-Name-Server, Netbios-Node, Netbios-Scope, Router-Discovery
              Static-Route, Classless-Static-Route,
Classless-Static-Route-Microsoft, Vendor-Option

21:26:10.522590 02:16:3f:0c:10:0d > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800),
length 345: (tos 0x0, ttl 64, id 58362, offset 0, flags [none], proto UDP (17),
length 331)
    15.3.2.1.67 > 255.255.255.255.68: BOOTP/DHCP, Reply, length 303, xid
0xcc8a146d, secs 6656, Flags [Broadcast]
          Your-IP 10.13.128.194
          Server-IP 10.13.128.1
          Client-Ethernet-Address 02:16:3e:4b:cc:53
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Offer
            Server-ID Option 54, length 4: 10.13.128.1
            Lease-Time Option 51, length 4: 900
            RN Option 58, length 4: 450
            RB Option 59, length 4: 787
            Subnet-Mask Option 1, length 4: 255.255.224.0
            BR Option 28, length 4: 10.13.159.255
            Default-Gateway Option 3, length 4: 10.13.128.1
            Domain-Name-Server Option 6, length 4: 10.13.128.1
            Domain-Name Option 15, length 9: "novalocal"

Notice the source IP address here is that of my Internet-facing interface, not
the IP on the bridge.  That's actually causing me to drop the packet on the
bridge due to an ebtables rule that only allows responses from 10.13.128.1 (for
security reasons).  Since I'm starting dnsmasq to only listen on that IP, I
don't know why it's responding using the other, unless the Linux network stack
is doing that?

The only thing I've noticed that's different is that in the R2 request there is
an additional option:

	NOAUTO Option 116, length 1: Y

Is that possibly causing dnsmasq to respond differently?  I haven't dug into the
code yet, figured I'd ask on the list in case it's been seen before.

Thanks for any help,

-Brian