Wrt1900, MAC for "br-lan" and "wan", Firewall?

I wonder "why" the MAC address for the "wan" and "br-lan" have the same value. MY "simple" understanding of ethernet is.. MAC addresses should not be duplicated on a "network segment". SInce the wrt1900 has multiple ethernet interfaces/connectors, why would one configure the MAC address for the "wan" to be the same as the "br-lan". I suspect my understanding of "how" the wrt1900 "works", as relates to configuration of the physical ethernet connectors has a big hole. Why do I care? How are "packets" sent to WRT1900 on the "br-lan" or any of the "lan" connectors, not showing up on the "wan". Why is the "wan" not configured with a MAC address that is NOT the same as the "br-lan" or any of the "devices" that constitute the "br-lan"?

is your wan used as wan ?

Is the ':98:C0:46 address the same as on the label?

This is often seen where in the change to DSA, the "built in" mac addresses have not been read correctly.

Very strange though, the eth0 and eth1 physical interfaces both have locally administered mac addresses....
How did that happen?

Yes. wan is wan See below.

nterfaces » wan

Status

Device: wan
Uptime: 7d 23h 23m 9s
MAC: 94:10:3E:98:C0:46
RX: 99.56 GB (83290749 Pkts.)
TX: 7.82 GB (42897629 Pkts.)
IPv4: 47.220.160.46/22

Protocol

Device

Disable this interface

Bring up on boot

Hostname to send when requesting DHCP

  • Send the hostname of this device

wow, that was pretty unreadable ...

Yes, :98:c0:46 is the value on the label.
As to "how did that happen". The sysupgrade was done "without" preserving settings. Changes since sysupgrade include wifi configuration and Hostname. Initial sysupgrade before "any changes" had the indicated ethernet addresses. I had reason to "suspect" I had done something (lan or device changes) so I did sysupgrade without preserving and what you see is what I got. I have "concerns" because "Shields UP" sees some ports in "stealth" mode.

Why is that a concern?

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Why o why MAC differ for 2 interfaces - because there are users who loop LAN and WAN.

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shields up - your provider actively blocks UPNP.

What version of OpenWrt, must be an old one.

As to "what version".

Status

System

Hostname OpenWrt
Model Linksys WRT1900AC v1
Architecture ARMv7 Processor rev 2 (v7l)
Target Platform mvebu/cortexa9
Firmware Version OpenWrt 23.05.3 r23809-234f1a2efa / LuCI openwrt-23.05 branch git-24.086.45142-09d5a38
Kernel Version 5.15.150
Local Time 2024-05-18 06:43:53
Uptime 0h 8m 36s
Load Average 0.00, 0.01, 0.00
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There is noproblem with your router.
you can test with other tools:

brada4,
Thank you!!! for the link. The site was new to me. I have invested a few minutes reading/surfing the site. Good STUFF!

FYI... The NMAP GUI site has a bit more clickbait than I typically tolerate.