Need debugging suggestions: No longer see ethernet interfaces after upgrading Mac from 10.15.1 to 10.15.3

edit

So by

crw-rw----  1 root  access_bpf   23,  78 Feb 17 09:29 /dev/bpf*

do you mean that doing ls -l /dev/bpf* shows a list of /dev/bpfN devices, all of which have permissions rw-rw----, an owner of root, and a group of access_bpf?

What does the command id print?

Yes,

haven:~ drm$ ls -l /dev/bpf*
crw-rw----  1 root  access_bpf   23,   0 Feb 17 09:29 /dev/bpf0
crw-rw----  1 root  access_bpf   23,   1 Feb 17 09:30 /dev/bpf1

And

haven:~ drm$ id
uid=501(drm) gid=20(staff) groups=20(staff),701(com.apple.sharepoint.group.1),501(access_bpf),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),98(_lpadmin),398(com.apple.access_screensharing),399(com.apple.access_ssh),33(_appstore),100(_lpoperator),204(_developer),250(_analyticsusers),395(com.apple.access_ftp),400(com.apple.access_remote_ae)

What do the commands tcpdump -D and dumpcap -D print?

Excellent question!

haven:~ drm$ /usr/sbin/tcpdump -D
tcpdump: SIOCGIFMEDIA on llw0 failed: Device power is off

Same message from "/Applications/Wireshark.app/Contents/MacOS/dumpcap".

This lead me to google the error, which led me to: https://ask.wireshark.org/question/13.... I apologize that my searching didn't find that before I posted.

Enabling WiFi allows tcpdump and dumpcap to see all interfaces. They disappear again when WiFil is disabled.