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Tcpdump Tips & Tricks



Tcpdump Tips & Tricks


 Tcpdump Tips & Tricks 
TCPDUMP USAGE




This article gives a few useful tcpdump examples. Tcpdump is a Linux network packet analyser. Using Tcpdump, the system administrator can see packets of data coming in and going out of a Linux system. Tcpdump is a great tool for network based application troubleshooting.

Listening to packets on “eth0″:
# tcpdump -i eth0












Listening for HTTP (port 80) packets only:


# tcpdump port 80








Listening for HTTP packets on “eth0″:


# tcpdump -i eth0 port 80








Listening for packets on all ports and all ethernet devices except SSH (port 22) packets:


# tcpdump not port 22








Listening for packets with a source IP address of “10.1.1.5″:


# tcpdump src 10.1.1.5








Listening for packets that are not SSH (port 22) packets and that have a souce address of “10.1.1.5″:


# tcpdump not port 22 and src 10.1.1.5








Listening for ICMP (ping) packets on all ethernet devices:


# tcpdump icmp








Saving tcpdump output for later analysis:


# tcpdump -w tcpdump.out








Using Tcpdump with input from a file created using the “-w” option (above):


#tcpdump -r tcpdump.out








Using Tcpdump with input from a file created using the “-w” option (above) and filtering for ICMP packets only:


#tcpdump icmp -r tcpdump.out





















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