is tcpdump affected by iptables filtering? [closed]

Question

If my development machine has an iptables rule to FORWARD some packets, are those packets being captured by tcpdump? I have this question because I know there exist other chain called INPUT which filters packets to apps, if a packet is routed to FORWARD chain, will it reach tcpdump app?

May you make some reliable reference to official documentation or express well explained ideas to solve this question?

Answer 1

TCPDump captures traffic from the hardware device. Iptables handles network frames at a different level.

So the answer is no, TCPDump will capture traffic only when it passes through the network card. IPtables can be taking inbound traffic on a card that TCPDump is monitoring, but may send it outbound on a different network card that is not being monitored by TCPDump.

Just remember, TCPDump will catch the traffic only if it passes through the network card.