I am trying to set up a new failover DHCP server using the Linux isc-dhcp-server package. I had a working failover server that needed to be replaced because it's old. I copied the dhcpd.conf file from the old server to the new one so I'm fairly sure it is correct. But if I shut down the primary server, it does not fail over. I suspect a config problem at the switch -- which I do not own or control. So what I want to do is to sniff packets to see if the DHCPREQUEST packets are even getting to the failover server. Anybody know how I can do that on Linux? My preferred packet sniffer is ngrep but I'll use something else if someone can give me the command syntax. I probably should mention that I need to do this remotely. I am working from home because of the pandemic, of course. -- John G. Heim; jheim@math.wisc.edu; 608-263-4189