Errors in the log (nlbwmon, netlink buffer out of memory)

Installing and Using OpenWrt
1

Very often I see these errors in the logs. What does it mean and how to fix?

Sun May  4 08:00:39 2025 daemon.err nlbwmon[2614]: Netlink receive failure: Out of memory
Sun May  4 08:00:39 2025 daemon.err nlbwmon[2614]: Unable to dump conntrack: No buffer space available
Sun May  4 08:09:09 2025 daemon.err nlbwmon[2614]: Netlink receive failure: Out of memory
Sun May  4 08:09:09 2025 daemon.err nlbwmon[2614]: Unable to dump conntrack: No buffer space available
Sun May  4 08:11:09 2025 daemon.err nlbwmon[2614]: Netlink receive failure: Out of memory
Sun May  4 08:11:09 2025 daemon.err nlbwmon[2614]: Unable to dump conntrack: No buffer space available
2

By searching the forum for the error you just posted.

3

didn't find any proper solution...

4

So you've tried Nlbwmon out of memory (yet another...) ?

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5

Is it possible to do on Luci interface?

6

You said you've already tried those solutions ?

7

On current main branch I see a lot of messages.

daemon.err nlbwmon: Netlink receive failure: Out of memory
daemon.err nlbwmon: Unable to dump conntrack: No buffer space available

That's on R7800 ipq-806x kernel 6.6.93.
My settings from 23.05 are the same and on 23.05 I have never seen that error appear after making bellow settings changes.

config nlbwmon
	option netlink_buffer_size '1573376' <-- I changed this
	option commit_interval '24h'
	option database_directory '/var/lib/nlbwmon'
	option database_generations '10'
	option database_interval '1'
	option database_limit '10000'
	option protocol_database '/usr/share/nlbwmon/protocols'
	list local_network '192.168.0.0/16'
	list local_network '172.16.0.0/12'
	list local_network '10.0.0.0/8'
	list local_network 'lan'
	option refresh_interval '5m'

/target/linux/ipq806x/base-files/etc/init.d/bootcount

	#nlbwmon fix
	sysctl -w vm.min_free_kbytes=65536
	sysctl -w net.netfilter.nf_conntrack_max=32768
	sysctl -w net.core.rmem_default=524288
	sysctl -w net.core.wmem_default=524288
	sysctl -w net.core.rmem_max=1573376
	sysctl -w net.core.wmem_max=1573376

Any ideas or solutions?
The good part of it is that despite those errors nlbwmon works and counts traffic.

8

Have you followed the instructions in the link above?

Are you the OP (Denim)?

9

It's seen form my post that I've followed them. I'm not the OP.
Sorry, "again" was simply a lapse.
I edited my post to be clearer about the case.

10

Thanks for that, although you were clear.

I don't see that you followed. Did you enter these in /etc/sysctl.d/99-user.conf - as noted in the link above?

(Not sure if the method you used actually works.)

11

Unless something changed fundamentally from 23.05 I see this

root@R7800:~# sysctl net.core.rmem_default
net.core.rmem_default = 524288
root@R7800:~# sysctl net.core.rmem_max
net.core.rmem_max = 1573376
root@R7800:~# sysctl net.core.wmem_max
net.core.wmem_max = 1573376

so should work.

On another router running main snapshot I have this. I don't use nlbwmon on it.

root@QNAP:~# sysctl net.core.wmem_max
net.core.wmem_max = 212992
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12

Make your /etc/sysctl.conf look like this:

# Defaults are configured in /etc/sysctl.d/* and can be customized in this file
rp_filter = 2
#net.core.rmem_max=3146752
#net.core.wmem_max=3146752
net.core.rmem_default=10485760
net.core.wmem_default=10485760
net.core.rmem_max=10485760
net.core.wmem_max=10485760

Change your /etc/config/nlbwmon with:
uci set nlbwmon.@nlbwmon[0].netlink_buffer_size='10485760'
uci commit nlbwmon

Finally restart nlbwmon:
service nlbwmon restart

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