[Solved] DNS problem for windows machines

[ryangit]

Hi, I've setup OpenWRT 18.06.1 on linksys wrt1900ac v1, everything is working fine for mac / linux machines, but on some windows machine and my kindle (and some IoT devices) it doesn't get DNS responds. I think it may be a DNSmasq problem because if I set DHCP-option 6 to directly advertise DNS servers(75.75.75.75, since my ISP is comcast), things are working just fine.

I still want to use DNSmasq, so any thoughts on how to debug are appreciated!

Here is the content of /etc/config/dhcp

config dnsmasq
	option domainneeded '1'
	option localise_queries '1'
	option rebind_protection '1'
	option rebind_localhost '1'
	option local '/lan/'
	option domain 'lan'
	option expandhosts '1'
	option authoritative '1'
	option readethers '1'
	option leasefile '/tmp/dhcp.leases'
	option resolvfile '/tmp/resolv.conf.auto'
	option localservice '1'
	option nonwildcard '0'

config dhcp 'lan'
	option interface 'lan'
	option start '100'
	option limit '150'
	option leasetime '12h'
	list dns '192.168.1.1'
	list dns 'fdf8:c5:e7e4::1'
	option ra 'server'
	option dhcpv6 'server'
	option ra_management '1'
	list dhcp_option '6,75.75.75.75,75.75.76.76'

config dhcp 'wan'
	option interface 'wan'
	option ignore '1'

config odhcpd 'odhcpd'
	option maindhcp '0'
	option leasefile '/tmp/hosts/odhcpd'
	option leasetrigger '/usr/sbin/odhcpd-update'

config host
	option name 'homeserver'
	option dns '1'
	option mac 'B8:88:E3:3B:5F:99'
	option ip '192.168.1.2

[vgaetera]

netstat -lnptu | grep dnsmasq
head -n -0 /etc/resolv.conf /tmp/resolv.conf.auto

[ryangit]

root@LEDE:~# netstat -lnptu | grep dnsmasq
tcp        0      0 0.0.0.0:53              0.0.0.0:*               LISTEN      2019/dnsmasq
tcp        0      0 :::53                   :::*                    LISTEN      2019/dnsmasq
udp        0      0 0.0.0.0:53              0.0.0.0:*                           2019/dnsmasq
udp        0      0 0.0.0.0:67              0.0.0.0:*                           2019/dnsmasq
udp        0      0 :::53                   :::*                                2019/dnsmasq

root@LEDE:~# head -n -0 /etc/resolv.conf /tmp/resolv.conf.auto
==> /etc/resolv.conf <==
search lan
nameserver 127.0.0.1

==> /tmp/resolv.conf.auto <==
# Interface wan
nameserver 75.75.75.75
nameserver 75.75.76.76
nameserver 8.8.8.8
nameserver 4.4.4.4
# Interface wan6
nameserver 2001:558:feed::1
nameserver 2001:558:feed::2
nameserver 2001:4860:4860::8888
nameserver 2001:4860:4860::8844

[trendy]

Enable Query logging in General Settings of DHCP and DNS.
View the rolling logs of dnsmasq: logread -f | grep dnsmasq
From your windows run in CMD: nslookup www.google.com
Use an address that works and one that doesn't work for you.
Copy the logs and paste them here. Let us know which site worked and which not.
You can exit the rolling logs with Ctrl-c

[jeff]

You can also decline to use the Comcast DNS servers. That they’re unreliable is only the first of many reasons not to use them.

[ryangit]

My bad, I made a stupid mistake and just found out I misconfigured the firewall which resulted in blocking port 58 for those devices, that's why some of my devices work and some don't.

Also switched dns server from comcast to google. Thanks for all the input!

[tmomas]

@ryangit If your problem is solved, please consider marking this topic as [Solved]. (Click the pencil behind the topic...)