how to tell tcpdump only to capture packets that go throught iptables

[fsluck]

how to tell tcpdump only to capture packets that go throught iptables

i want to calculate how many icmp packets are received after i setup several iptables rules for icmp.

thanks

[Denis Ovsienko]

Post by fsluck
how to tell tcpdump only to capture packets that go throught iptables

iptables can send packets to NetFilter loggger (-j NFLOG --nflog-group 20) on which tcpdump can capture (-i nflog:20)

Post by fsluck
i want to calculate how many icmp packets are received  after i setup several iptables rules for icmp.

Mere counting is possible even without tcpdump: each iptables rule has counters for bytes and packets (iptables -vnL INPUT).