A junior analyst is trying to use the tcpdump –i eth1 command on an Ubuntu system, but it is not working. What could be the problem?

The most likely issue is that:

The tcpdump command requires root-level privilege.

Running tcpdump typically requires superuser (root) privileges because it involves capturing and analyzing network packets, which is a sensitive operation. You can use sudo to run tcpdump with elevated privileges:

sudo tcpdump -i eth1

The other options mentioned are not common reasons for the tcpdump command to fail. In fact, specifying the interface with the -i option is valid, and the -n and -v options are not required for the basic operation of tcpdump. The Ethernet adapter being in non-promiscuous mode doesn’t typically prevent tcpdump from running.