[Dnsmasq-discuss] Problems with --server

[David Erickson]

Hello-
I am using dnsmasq inside dd-wrt, I am a recent build of DD-WRT with
dnsmasq v2.72.  I am having problems getting server domain forwarding to
work, in particular I can tcpdump and watch my request come in on the LAN
port, the request from dnsmasq head out the WAN port to the upstream
server, the answer comes back from the upstream server, then dnsmasq
returns an empty result to me.

Cmdline:
dnsmasq -u root -g root --conf-file=/tmp/dnsmasq.conf

Conf:
interface=br0
resolv-file=/tmp/resolv.dnsmasq
all-servers
strict-order
domain=zonk.some.domain
dhcp-leasefile=/tmp/dnsmasq.leases
dhcp-lease-max=50
dhcp-option=lan,3,10.129.0.1
dhcp-range=lan,10.129.0.100,10.129.0.150,255.255.255.0,1440m
stop-dns-rebind
log-queries
# some.domain
server=/some.domain/10.128.0.1
rev-server=10.128.0.0/24,10.128.0.1
# dc.some.domain
server=/dc.some.domain/10.128.64.1
rev-server=10.128.64.0/24,10.128.64.1

And here is the tcpdump interchange:

Me -> dnsmasq
23:32:32.301531 IP (tos 0x0, ttl 64, id 49653, offset 0, flags [none],
proto UDP (17), length 86)
    10.129.0.138.65190 > 10.129.0.1.53: [udp sum ok] 8601+ A?
dc-terminal.dc.some.domain. (58)
23:32:32.301567 IP (tos 0x0, ttl 64, id 49653, offset 0, flags [none],
proto UDP (17), length 86)
    10.129.0.138.65190 > 10.129.0.1.53: [udp sum ok] 8601+ A?
dc-terminal.dc.some.domain. (58)

dnsmasq -> upstream device
23:32:32.302130 IP (tos 0x0, ttl 64, id 12450, offset 0, flags [DF], proto
UDP (17), length 86)
    10.128.0.119.46851 > 10.128.64.1.53: [udp sum ok] 58951+ A?
dc-terminal.dc.some.domain. (58)

upstream device -> dnsmasq
23:32:32.317469 ethertype IPv4, IP (tos 0x0, ttl 63, id 58992, offset 0,
flags [DF], proto UDP (17), length 102)
    10.128.64.1.53 > 10.128.0.119.46851: [udp sum ok] 58951* q: A?
dc-terminal.dc.some.domain. 1/0/0 dc-terminal.dc.some.domain. [0s] A
10.128.64.3 (74)
23:32:32.317505 IP (tos 0x0, ttl 63, id 58992, offset 0, flags [DF], proto
UDP (17), length 102)
    10.128.64.1.53 > 10.128.0.119.46851: [udp sum ok] 58951* q: A?
dc-terminal.dc.some.domain. 1/0/0 dc-terminal.dc.some.domain. [0s] A
10.128.64.3 (74)

dnsmasq -> Me (with an empty answer payload)
23:32:32.317777 IP (tos 0x0, ttl 64, id 65207, offset 0, flags [DF], proto
UDP (17), length 86)
    10.129.0.1.53 > 10.129.0.138.65190: [bad udp cksum 0x15e0 -> 0x50d2!]
8601* q: A? dc-terminal.dc.some.domain. 0/0/0 (58)
23:32:32.317804 IP (tos 0x0, ttl 64, id 65207, offset 0, flags [DF], proto
UDP (17), length 86)
    10.129.0.1.53 > 10.129.0.138.65190: [udp sum ok] 8601* q: A?
dc-terminal.dc.some.domain. 0/0/0 (58)

Any help or suggestions on troubleshooting would be greatly appreciated.

Thanks,
David
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