[OpenWrt-Devel] [openwrt-devel] dnsmasq sometimes does not respond to DHCP Discovery or DHCP Request

[Xuebing Wang]

Hi community,

I am using OpenWRT chaos_calmer on Atheros MIPS platform. I observed 
that sometimes dnsmasq does not respond to DHCP Discovery or DHCP Request.

I have 2 test setups:
1) Have a Ubuntu 16.04.1 PC configured as "Wireshark Capture using a 
machine-in-the-middle" as below:
https://wiki.wireshark.org/CaptureSetup/Ethernet#Capture_using_a_machine-in-the-middle
2) Connect Ubuntu laptop to my another OpenWRT + Atheros board.

When this issue happens, DHCP lease file /tmp/dhcp.leases is not created.

Wireshark Capture shows that dhcp client does send "DHCP Discovery" and 
"DHCP Request", but dnsmasq does not respond.

Running 'dhclient eth0' at Linux dhcp client can not recover.

After '/etc/init.d/dnsmasq restart' at openwrt, then I can do 'dhclient 
eth0' at Linux dhcp client to get it working.

The occurrence rate is about 5% to 10%.

I was having both dnsmasq + odhcpd. After remove odhcpd, this issue 
still happens, but seemingly with a lower occurrence rate.

Has anyone seen similar issue?

Thanks.
xuebing wang
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