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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">While Running tests in an openwrt based IP gateway, we noticed
<span style="color:#1F497D">a dns problem running </span>openwrt <span style="color:#1F497D">
in a gateway. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">When DNS proxy ( dnsmasq) forward the DNS reply, the Answer of section was extracted.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"></span><o:p></o:p></p>
<p class="MsoNormal">Please refer to the following tests for the problem description.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt;line-height:115%"><span style="color:#1F497D">192.168.42.135 ------------------------ (192.168.42.1 GATEWAY 10.10.200.2)------………… (1.1.1.1 DNS server)</span><o:p></o:p></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>The Gateway LAN interface pre-configured as 192.168.42.1. The Gateway LAN section is in 192.168.42.0/255.255.255.0 subnet<o:p></o:p></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>A LAN Device is assigned IP to 192.168.42.135 from the DHCP server in the gateway.<o:p></o:p></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>Have Gateway wan link set to network in subnet <span style="color:#1F497D">
10.10.200</span>.xx/255.255.255.0<span style="color:#1F497D">.<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">4.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">Set up a DNS Server in WAN with IP: 1.1.1.1<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">5.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>DHCP server (not in the picture) in<span style="color:#1F497D"> the WAN subnet
</span>assign Gateway wan IP as <span style="color:#1F497D">10.10.200.2<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">6.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D"> The LAN client initiates a DNS query. The query has source IP 192.168.42.135 and destination IP 192.268.42.1 (in lan.cap message 1)<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">7.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">The Gateway forwards the query to dns server. The forwarded query has the source IP 10.10.200.2 and destination 1.1.1.1 (in wan.cap msg 1)<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">8.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">DNS server 1.1.1.1 sends DNS resolution response with resolved dns address. The response sends to the Gateway 10.10.200.2. (in wan.cap msg 2)<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l1 level1 lfo1">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">9.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">The Gateway forwards the response to the client; but the forwarded response does not have the Answer. (in lan.cap msg 2)<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:30.75pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"> Please review the attached wireshark.<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D">Questions:<o:p></o:p></span></p>
<p class="MsoNormalCxSpLast" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"> I wonder if this problem is due to:<o:p></o:p></span></p>
<p class="MsoListParagraphCxSpFirst" style="margin-bottom:10.0pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">My tested openwrt is an older version; OR<o:p></o:p></span></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">A simple config problem<o:p></o:p></span></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;text-indent:-.25in;line-height:115%;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:#1F497D">The worst case is a S/W problem in dnsmasq that requires code modification<o:p></o:p></span></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D">Anyone know the solution or ever see this problem, please gives us a reply.<o:p></o:p></span></p>
<p class="MsoListParagraphCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoListParagraphCxSpLast" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D">Here is the version./release information the openwrt I am using:<o:p></o:p></span></p>
<p class="MsoNormalCxSpFirst" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:.5in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">The </span><span style="color:#1F497D">etc/banner file
<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:1.0in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">Release : 14.3 <o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:1.0in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">Version: 14.44<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:.5in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">The /etc/openwrt_version file<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:1.0in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D"> 12.09.1<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:.5in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">The /etc/openwrt_release file<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:1.0in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">DISTRIB_REVISION="r42647"<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="margin-bottom:10.0pt;mso-add-space:auto;line-height:115%">
<span style="color:#1F497D"> ISTRIB_CODENAME="attitude_adjustment"<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:1.0in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">DISTRIB_TARGET="brcm63xx-arm-tch/HG1XPROTO"<o:p></o:p></span></p>
<p class="MsoNormalCxSpMiddle" style="mso-margin-top-alt:0in;margin-right:0in;margin-bottom:10.0pt;margin-left:1.0in;mso-add-space:auto;text-indent:.5in;line-height:115%">
<span style="color:#1F497D">DISTRIB_DESCRIPTION="OpenWrt Attitude Adjustment 12.09.1"<o:p></o:p></span></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal" style="text-indent:.5in">And the “uci show” related to the dnsmasq<o:p></o:p></p>
<p class="MsoNormal"> dhcp.@dnsmasq[0]=dnsmasq<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].domainneeded=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].filterwin2k=0<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].localise_queries=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].rebind_protection=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].rebind_localhost=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].local=/lan/<o:p></o:p></p>
<p class="MsoNormal"> dhcp.@dnsmasq[0].expandhosts=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].nonegcache=0<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].authoritative=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].readethers=1<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].leasefile=/tmp/dhcp.leases<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].resolvfile=/tmp/resolv.conf.auto<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].dhcpscript=/lib/dnsmasq/dhcp-event.sh<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].domain=qacafe.com<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in">dhcp.@dnsmasq[0].boguspriv=0<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in;text-indent:.5in"><span style="color:black"><a href="mailto:dhcp.@dnsmasq[0].strictorder=1"><span style="color:black">dhcp.@dnsmasq[0].strictorder=1</span></a>
<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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