monitoring.md

Bandwidth Monitoring

OpenWRT comes with a decent selection of traffic monitoring tools, both CLI and web UI. I use nlbwmon, which integrates well with the web interface and creates pretty graphs. Here's how to install it.

Enable conntrack accounting

nlbwmon uses the Linux netfilter conntrack subsystem to track connections and packet counts, so you need to make sure the nf_conntrack kernel module is loaded on your host system (it probably is). But just to check:

$ lsmod | grep nf_conntrack

Conntrack accounting is off by default, so we have to enable it inside the container:

$ sudo ip netns exec ${CONTAINER} sysctl -w net.netfilter.nf_conntrack_acct=1

Alternatively this can be enabled when creating the container by adding the flag

--sysctl net.netfilter.nf_conntrack_acct=1

to the docker create command in run.sh.

Install packages

Inside the container:

# opkg install nlbwmon luci-app-nlbwmon
# service nlbwmon enable
# service nlbwmon start

There should now be a "Bandwidth Monitor" section in LuCI.

Configuration

The default configuration is extremely conservative with storage. Since we're not running on a device with 4MB flash storage, we can increase the defaults:

# cat <<EOF | uci import
package nlbwmon
config nlbwmon
	option  refresh_interval      '30s'
	option  database_directory    '/var/lib/nlbwmon'
	option  database_interval     '1'
	option  protocol_database     '/usr/share/nlbwmon/protocols'
	option  commit_interval       '60s'
	option  database_limit        '0'
	option  database_generations  '0'
	list    local_network         "${LAN_SUBNET}"
	list    local_network         'lan'
EOF
# service nlbwmon restart

For a more complex (and useful) solution, see Monitoring with InfluxDB + Grafana