Dnsmasq failing since 2-3 weeks

Installing and Using OpenWrt
1

Hi Everyone,

Since like 2-3 weeks I have a constant issue with dnsmasq. It stops working and logging error:

dnsmasq[1]: failed to send packet: Resource temporarily unavailable

There is nothing in logs what will indicate obvious issues. Upstream DNS servers are fine. What I usually do is restarting dnsmasq service and it starts working again for few hours (sometimes minutes). I was running OpenWrt 24.10.0 when this issue started. I updated to latest stable OpenWrt 24.10.1 and issue persist. I even installed dnsmasq-full to see if this fix it.

I ended up with writing my shell script which test each few minutes if dnsmasq responds on LAN interface to DNS query and restart it if not.

I run OpenWrt for 3 or even 4 years and I haven't got any serious issues until now. My hardware is BT Home Hub 5A (lantiq/xrx200).

Does anybody have some ideas where to look to solve this issues.
I may end up with configuring whole router from scratch but I have quite big configuration (multiple zones, lots of static ip leaeses and few more things) and I'm trying to avoid this.

2

Let's see your /etc/config/dhcp and network files, please.

Interesting...an old thread, a user had such a large network config.

3

Below are important bits from dhcp and network config files.

/etc/config/dhcp:

config dnsmasq
	option domainneeded '1'
	option localise_queries '1'
	option rebind_protection '1'
	option local '/lan/'
	option domain 'lan'
	option expandhosts '1'
	option cachesize '1000'
	option authoritative '1'
	option readethers '1'
	option leasefile '/tmp/dhcp.leases'
	option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
	option localservice '1'
	option ednspacket_max '1232'
	option sequential_ip '1'
	option allservers '1'
	list notinterface 'wan'

config dhcp 'lan'
	option interface 'lan'
	option start '100'
	option limit '140'
	option leasetime '12h'
	option dhcpv4 'server'
	option dhcpv6 'server'
	option ra 'server'
	list ra_flags 'managed-config'
	list ra_flags 'other-config'
	option dns_service '0'

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'
	option loglevel '3'

/etc/config/network:

config interface 'loopback'
	option device 'lo'
	option proto 'static'
	option ipaddr '127.0.0.1'
	option netmask '255.0.0.0'

config globals 'globals'
	option ula_prefix 'fdb5:05fa:cb6b::/48'
	option packet_steering '1'

config atm-bridge 'atm'
	option vpi '1'
	option vci '32'
	option encaps 'llc'
	option payload 'bridged'
	option nameprefix 'dsl'

config dsl 'dsl'
	option annex 'b'
	option ds_snr_offset '0'
	option xfer_mode 'ptm'
	option line_mode 'vdsl'

config device
	option name 'br-lan'
	option type 'bridge'
	list ports 'lan1'
	list ports 'lan2'
	list ports 'lan3'
	list ports 'lan4'
	option ipv6 '0'

config device
	option name 'lan1'
	option macaddr 'd0:57:94:b0:a4:aa'

config device
	option name 'lan2'
	option macaddr 'd0:57:94:b0:a4:aa'

config device
	option name 'lan3'
	option macaddr 'd0:57:94:b0:a4:aa'

config device
	option name 'lan4'
	option macaddr 'd0:57:94:b0:a4:aa'

config interface 'lan'
	option device 'br-lan'
	option proto 'static'
	option ipaddr '192.168.1.254'
	option netmask '255.255.255.0'
	option ip6assign '60'
	option delegate '0'

config device
	option name 'dsl0'
	option macaddr 'xx:xx:xx:xx:xx:xx'
	option ipv6 '0'

config interface 'wan'
	option device 'dsl0.101'
	option proto 'pppoe'
	option ipv6 '1'
	option mtu '1500'

config device
	option type '8021q'
	option ifname 'dsl0'
	option vid '101'
	option name 'dsl0.101'
	option ipv6 '0'

config interface 'dmz'
	option proto 'static'
	option device 'wan'
	option ipaddr '192.168.2.254'
	option netmask '255.255.255.0'
	option delegate '0'

config device
	option name 'wan'
	option ipv6 '0'

For testing purpose I decided to downgrade OpenWrt version to previous mayor release 23.05.5 and all issues disappeared. I'm running this version for currently 24 hours and it was no single issue with dnsmasq.
Maybe 24 hours is not enough for saying that issues is gone but will wee after few days.

Comparing two versions:

OpenWrt 23.05.5, r24106-10cc5fcd00
Linux router 5.15.167 #0 SMP Mon Sep 23 12:34:46 2024 mips GNU/Linux
dnsmasq - 2.90-2

OpenWrt 24.10.1, r28597-0425664679
Linux ap1.pelech.net 6.6.86 #0 SMP Sun Apr 13 16:38:32 2025 mips GNU/Linux
dnsmasq - 2.90-r4

Maybe there is issue with 6.x kernel version or something was added to new release of dnsmasq ?

4

my 24.10.1 is using a different version of dnsmasq, or is it a C&P error ?

 OpenWrt 24.10.1, r28597-0425664679
 -----------------------------------------------------
=== WARNING! =====================================
There is no root password defined on this device!
Use the "passwd" command to set up a new password
in order to prevent unauthorized SSH logins.
--------------------------------------------------
root@OpenWrt:~# opkg list-installed  | grep dns
dnsmasq - 2.90-r4
1 Like
5

Yeah. It was copy/paste "typo". Corrected in my previous answer.
Thanks

6

Looks like all is fine after downgrading to version 23.05.5. No single issue.