TCPDUMP

Command Line Options

-A Print frame payload in ASCII
-c <count> Exit after capturing count packets
-D List available interfaces
-e Print link-level headers
-F <file> Use file as the filter expression
-G <n> Rotate the dump file every n seconds
-i <iface> Specifies the capture interface
-K Don’t verify TCP checksums
-L List data link types for the interface
-n Don’t convert addresses to names
-p Don’t capture in promiscuous mode
-q Quick output
-r <file> Read packets from file
-s <len> Capture up to len bytes per packet
-S Print absolute TCP sequence numbers
-t Don’t print timestamps
-v[v[v]] Print more verbose output
-w <file> Write captured packets to file
-x Print frame payload in hex
-X Print frame payload in hex and ASCII
-y <type> Specify the data link type
-Z <user> Drop privileges from root to user

Capture Filter Primitives

[src|dst] host <host> Matches a host as the IP source, destination, or either
ether [src|dst] host <ehost> Matches a host as the Ethernet source, destination, or either
gateway host <host> Matches packets which used host as a gateway
[src|dst] net <network>/<len> Matches packets to or from an endpoint residing in network
[tcp|udp] [src|dst] port <port> Matches TCP or UDP packets sent to/from port
[tcp|udp] [src|dst] portrange <p1>-<p2> Matches TCP or UDP packets to/from a port in the given range
less <length> Matches packets less than or equal to length
greater <length> Matches packets greater than or equal to length
(ether|ip|ip6) proto <protocol> Matches an Ethernet, IPv4, or IPv6 protocol
(ether|ip) broadcast Matches Ethernet or IPv4 broadcasts
(ether|ip|ip6) multicast Matches Ethernet, IPv4, or IPv6 multicasts
type (mgt|ctl|data) [subtype <subtype>] Matches 802.11 frames based on type and optional subtype
vlan [<vlan>] Matches 802.1Q frames, optionally with a VLAN ID of vlan
mpls [<label>] Matches MPLS packets, optionally with a label of label
<expr> <relop> <expr> Matches packets by an arbitrary expression

Protocols

ether
fddi
icmp

ip

ip6

link
ppp
radio

rarp

slip
tcp
tr
udp
wlan

TCP Flags

tcp-urg tcp-rst
tcp-ack tcp-syn
tcp-psh tcp-fin

Modifiers

! or not
&& or and
|| or or

Examples

udp dst port not 53
host 10.0.0.1 && host 10.0.0.2
tcp dst port 80 or 8080
UDP not bound for port 53
Traffic between these hosts
Packets to either TCP port

ICMP Types

icmp-echoreply icmp-routeradvert icmp-tstampreply
icmp-unreach icmp-routersolicit icmp-ireq
icmp-sourcequench icmp-timxceed icmp-ireqreply
icmp-redirect icmp-paramprob icmp-maskreq
icmp-echo icmp-tstamp icmp-maskreply

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