OK, MY language problem, forgetting (or changed) terminology. I took the classes, passed the CNA certification, but never used that knowledge, not even in my home lab. I asked AI the difference between a promiscuous port and a mirror port, and learned that promiscuous was a mode on a NIC, and the port on the switch was in mirror, monitor or SPAN mode. OK, my jogged memory, I recall "monitor" ports and maybe SPAN mode, but really think i never heard it called mirror. I also did not want to wait to order and ship a managed switch, and either did not look hard enough, or misunderstood (or maybe it was the case 20 years ago), thought buying one would be at least $100, maybe $200 or more. For the ones I have it would require finding the procedure to reset the login password, and I thought require setting up a USB serial port to connect to a terminal program, and finding/making a crossover cable, or configure the serial port correctly. I don't have any VMs, so promiscuous mode is not a security risk (per AI), and from 20 years ago, I thought unless the NIC was set to promiscuous mode, the NIC blocked all traffic to other addresses, and the computer was unaware of any traffic other than it's own. I think (but I've been wrong so much, would like to check) these would do it. My current office switch is 8 ports, but should probably replace it and increase, rather than adding another serial link in the chain? https://www.ebay.com/itm/277246206249 https://www.ebay.com/itm/197496478450 Also want to make sure I won't have to set up a second NIC on my desktop computer use to use for this. I may have a 100mb usb ethernet port, but I maybe only 10mb. Again, it doesn't sound like it from AI searches, but I've been wrong so much.... I found some online information on wireshark, maybe downloaded it, but this aging brain does better with paper. I'm trombones years old. (...led the big parade) I don't understand, do I neeed to make my NIC be promiscuous? will wireshark (and tshark) do that automatically?:
... It's a mirror port. A promiscuous port would on a computer that running something like Wireshark.
Carey
On 09/27/2025 8:02 AM CDT James Knott via Talk <talk@lists.gtalug.org> wrote:
On 9/26/25 23:48, CAREY SCHUG via Talk wrote:
setting up a managed switch so I can make a promiscuous port
Why do you keep talking about a promiscuous port on a switch? It's a mirror port. A promiscuous port would on a computer that running something like Wireshark.
As I mentioned earlier, you can make a "data tap" from a cheap 5 port managed switch, for about $20 - $30.
BTW, there's a Wireshark users guide under Help, in Wireshark.