Multiport NIC Gotcha

In light of current events, a little humor is always appreciated. Here is my story from yesterday:

Since I needed to be able to monitor multiple VLANs (using Security Onion and Parrot OS), I ordered one of these to replace the two-port NIC I had in my Proxmox server. After installing it, I ran ifconfig -a and edited /etc/network/interfaces accordingly.

After rebooting the box, I was immediately yelled at by my wife when Hulu stopped working downstairs. I ran a speed test on a computer to confirm the Internet was still working. However, I noticed my phone had no Internet.

Upon further investigation, I noticed in the UniFi controller that STP blocking was on for one of the switch ports. After logging into Proxmox and taking a look, it turned out that Proxmox automatically bridged three of the four ports on the new NIC together, which created a broadcast storm on my network. I removed the three-port bridge in the Proxmox interface, rebooted, and all was well again.

After correcting the momentary “hiccup,” I now have multiple “sniffing” interfaces. Bonus: I installed the old two-port NIC in my main desktop computer, which makes accessing certain media devices on a different subnet much easier. I created a firewall rule in pfSense to block Internet access to the second port.


That is hilarious. I have not discovered a “WAN down” alert faster than my wife.

Sounds like you are reinforcing the idea that I need a second NIC in my main machine to connect to iSCSI on its own VLAN. Grr. Not what I was hoping. Wanted to handle it all in software.

Gaming kids work even faster (and louder).

Oh that’s interesting, I just ordered a quad port NIC to go into a cheap box arriving soon which will host Proxmox so that I can run Security Onion !