[OpenWrt-Devel] dnsmasq strip out the ANswers from the DNS reply.

Kao Kevin Kevin.Kao at technicolor.com
Thu Oct 30 16:32:49 EDT 2014


While Running tests in an openwrt based IP gateway, we noticed a dns problem running openwrt in a gateway.
When DNS proxy ( dnsmasq) forward the DNS reply, the Answer of section was extracted.
Please refer to the following tests for the problem description.  ------------------------  (  GATEWAY  ( DNS server)

1.      The Gateway LAN interface pre-configured as The Gateway LAN section is in subnet

2.      A LAN Device is assigned IP to from the DHCP server in the gateway.

3.      Have Gateway wan link set to network in subnet 10.10.200.xx/

4.      Set up a DNS Server in WAN with IP:

5.      DHCP server (not in the picture) in the WAN subnet assign Gateway wan IP as

6.       The LAN client initiates a DNS query. The query has source IP and destination IP (in lan.cap message 1)

7.      The Gateway forwards the query to dns server. The forwarded query has the  source IP and destination  (in wan.cap msg 1)

8.      DNS server sends DNS resolution response with resolved dns address. The response sends to the Gateway (in wan.cap msg 2)

9.      The Gateway forwards the response to the client; but the forwarded response does not have the Answer.    (in lan.cap msg 2)

    Please review the attached wireshark.


     I wonder if this problem is due to:

1.      My tested openwrt is an older version; OR

2.      A simple config problem

3.      The worst case is a S/W problem in dnsmasq that requires code modification

Anyone know the solution or ever see this problem, please gives us a reply.

Here is the version./release information the openwrt I am using:

The etc/banner file

Release : 14.3

Version: 14.44

The /etc/openwrt_version  file


The /etc/openwrt_release file




DISTRIB_DESCRIPTION="OpenWrt Attitude Adjustment 12.09.1"

And the "uci show" related to the dnsmasq
                              dhcp. at dnsmasq[0]=dnsmasq
dhcp. at dnsmasq[0].domainneeded=1
dhcp. at dnsmasq[0].filterwin2k=0
dhcp. at dnsmasq[0].localise_queries=1
dhcp. at dnsmasq[0].rebind_protection=1
dhcp. at dnsmasq[0].rebind_localhost=1
dhcp. at dnsmasq[0].local=/lan/
                              dhcp. at dnsmasq[0].expandhosts=1
dhcp. at dnsmasq[0].nonegcache=0
dhcp. at dnsmasq[0].authoritative=1
dhcp. at dnsmasq[0].readethers=1
dhcp. at dnsmasq[0].leasefile=/tmp/dhcp.leases
dhcp. at dnsmasq[0].resolvfile=/tmp/resolv.conf.auto
dhcp. at dnsmasq[0].dhcpscript=/lib/dnsmasq/dhcp-event.sh
dhcp. at dnsmasq[0].domain=qacafe.com
dhcp. at dnsmasq[0].boguspriv=0
dhcp. at dnsmasq[0].strictorder=1<mailto:dhcp. at dnsmasq[0].strictorder=1>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.infradead.org/pipermail/openwrt-devel/attachments/20141030/f62ed673/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: wan.cap
Type: application/octet-stream
Size: 298 bytes
Desc: wan.cap
URL: <http://lists.infradead.org/pipermail/openwrt-devel/attachments/20141030/f62ed673/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: lan.cap
Type: application/octet-stream
Size: 234 bytes
Desc: lan.cap
URL: <http://lists.infradead.org/pipermail/openwrt-devel/attachments/20141030/f62ed673/attachment-0001.obj>
-------------- next part --------------
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org

More information about the openwrt-devel mailing list