TCPDUMP is a command based utility that is very robust and extremely useful for sniffing traffic. Here is some basic usage of this command.

Capture from source IP

tcpdump -i eth0 src SOURCE_IP

Capture from destination IP

tcpdump -i eth0 dst DESTINATION_IP

Capture certain number of packets

tcpdump -c 5 -i eth0

Print Captured Packets in ASCII

tcpdump -A -i eth0

Display available interfaces

tcpdump -D

Display Captured Packets in HEX and ASCII

tcpdump -XX -i eth0

Capture to a file

tcpdump -w file_log -i eth0

Read Captured Packet File

tcpdump -r file_log

Only capture TCP packets

tcpdump -i eth0 tcp

Capture specific port

tcpdump -i eth0 port 22