Hi,

I am trying to monitor Ethernet packets by using TP-Link router Ethernet ports as  sniffer.

I am unable to see all the packets, however able to see some packets using tcpdump as given below:

can somebody help me:

21:13:35.888912 STP 802.1d, Config, Flags [none], bridge-id 8000.xx:xx:xx:xx:xx:xx.8001, length 43
21:13:37.888930 STP 802.1d, Config, Flags [none], bridge-id 8000.xx:xx:xx:xx:xx:xx.8001, length 43
21:13:39.888964 STP 802.1d, Config, Flags [none], bridge-id 8000.xx:xx:xx:xx:xx:xx.8001, length 43
21:13:41.888976 STP 802.1d, Config, Flags [none], bridge-id 8000.xx:xx:xx:xx:xx:xx.8001, length 43
21:13:42.819205 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 263
21:13:42.819557 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 335
21:13:42.819837 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 331
21:13:42.820154 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 311
21:13:42.820675 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 343
21:13:42.820949 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 325
21:13:42.821279 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 327
21:13:42.821559 IP OpenWrt.lan.42741 > 239.255.255.250.1900: UDP, length 327
21:13:43.888977 STP 802.1d, Config, Flags [none], bridge-id 8000.xx:xx:xx:xx:xx:xx.8001, length 43
21:13:45.888986 STP 802.1d, Config, Flags [none], bridge-id 8000.xx:xx:xx:xx:xx:xx.8001, length 43

Am not sure, what I am missing in configuration.
Am creating separate interface on Lan Port.

Thanks and Regards,
Prasad