In the event anyone is ever looking for it, I had to figure this out for some debugging. Documenting for the future.
Inside of a cont-init.d shell script add the following lines
apt-get install -y wireshark usermod -a -G wireshark openhab chmod +x /usr/bin/dumpcap
Then at the karaf console:
openhab> shell:exec /usr/bin/dumpcap -P -w /openhab/userdata/atv1.pcap Capturing on 'eth0' File: /openhab/userdata/atv1.pcap