tcpdump commands

gistfile1.txt

# https://www.rationallyparanoid.com/articles/tcpdump.html

# DHCP debugging with tcpdump
# filter to match DHCP packets including a specific Client MAC Address:
tcpdump -i br0 -vvv -s 1500 '((port 67 or port 68) and (udp[38:4] = 0x3e0ccf08))'

# filter to capture packets sent by the client (DISCOVER, REQUEST, INFORM): 
tcpdump -i br0 -vvv -s 1500 '((port 67 or port 68) and (udp[8:1] = 0x1))'

# Monitoring on interface eth0
tcpdump -i eth0 -n port 67 and port 68

See the list of interfaces on which tcpdump can listen:
tcpdump -D

Listen on interface eth0:
tcpdump -i eth0

Listen on any available interface (cannot be done in promiscuous mode. Requires Linux kernel 2.2 or greater):
tcpdump -i any

Be verbose while capturing packets:
tcpdump -v

Be more verbose while capturing packets:
tcpdump -vv

Be very verbose while capturing packets:
tcpdump -vvv
Be verbose and print the data of each packet in both hex and ASCII, excluding the link level header:
tcpdump -v -X

Be verbose and print the data of each packet in both hex and ASCII, also including the link level header:
tcpdump -v -XX

Be less verbose (than the default) while capturing packets:
tcpdump -q

Limit the capture to 100 packets:
tcpdump -c 100

Record the packet capture to a file called capture.cap:
tcpdump -w capture.cap

Record the packet capture to a file called capture.cap but display on-screen how many packets have been captured in real-time:
tcpdump -v -w capture.cap

Display the packets of a file called capture.cap:
tcpdump -r capture.cap

Display the packets using maximum detail of a file called capture.cap:
tcpdump -vvv -r capture.cap

Display IP addresses and port numbers instead of domain and service names when capturing packets (note: on some systems you need to specify -nn to display port numbers):
tcpdump -n

Capture any packets where the destination host is 192.168.1.1. Display IP addresses and port numbers:
tcpdump -n dst host 192.168.1.1

Capture any packets where the source host is 192.168.1.1. Display IP addresses and port numbers:
tcpdump -n src host 192.168.1.1

Capture any packets where the source or destination host is 192.168.1.1. Display IP addresses and port numbers:
tcpdump -n host 192.168.1.1

Capture any packets where the destination network is 192.168.1.0/24. Display IP addresses and port numbers:
tcpdump -n dst net 192.168.1.0/24

Capture any packets where the source network is 192.168.1.0/24. Display IP addresses and port numbers:
tcpdump -n src net 192.168.1.0/24

Capture any packets where the source or destination network is 192.168.1.0/24. Display IP addresses and port numbers:
tcpdump -n net 192.168.1.0/24

Capture any packets where the destination port is 23. Display IP addresses and port numbers:
tcpdump -n dst port 23

Capture any packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:
tcpdump -n dst portrange 1-1023

Capture only TCP packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:
tcpdump -n tcp dst portrange 1-1023

Capture only UDP packets where the destination port is is between 1 and 1023 inclusive. Display IP addresses and port numbers:
tcpdump -n udp dst portrange 1-1023

Capture any packets with destination IP 192.168.1.1 and destination port 23. Display IP addresses and port numbers:
tcpdump -n "dst host 192.168.1.1 and dst port 23"

Capture any packets with destination IP 192.168.1.1 and destination port 80 or 443. Display IP addresses and port numbers:
tcpdump -n "dst host 192.168.1.1 and (dst port 80 or dst port 443)"

Capture any ICMP packets:
tcpdump -v icmp

Capture any ARP packets:
tcpdump -v arp

Capture either ICMP or ARP packets:
tcpdump -v "icmp or arp"

Capture any packets that are broadcast or multicast:
tcpdump -n "broadcast or multicast"

Capture 500 bytes of data for each packet rather than the default of 68 bytes:
tcpdump -s 500

Capture all bytes of data within the packet:
tcpdump -s 0