ncaptool8

Usage

Overview

ncaptool is a network capture library like libpcap (on which it is based) and tcpdump. It produces binary data in its own ncap format, which can be stored in a dump file or transmitted over a UDP socket. Unlike libpcap, it discards data link headers and only supports IPv4 and IPv6 packets, but it can perform reassembly of IP datagrams.

Options

-h

display this help text and exit

-d

increment debugging level

-m

increment message trace level

-f

flush outputs after every bufferable write

-r

destination of -s can be a remote (off-LAN) address

-w

use wallclock time not NCAP timestamp for -o files

-v

emit a traffic summary to stderr on exit

-S

stripe across all -s datasinks, round robin style

-e endline

specify continuation separator

-i ifname[+]

add interface as a datasource ('+' = promiscuous)

-b bpf

use this bpf pattern for any -i or -p datasources

-p file

add pcap file as a datasource ('-' = stdin)

-n file

add ncap file as a datasource ('-' = stdin)

-l socket

add datagram socket as a datasource (addr/port)

-g file

write msg trace to this file ('-' = stdout)

-o file

write ncap data to this file ('-' = stdout)

-s so[,r[,f]]

add this datagram socket as a datasink (addr/port) (optional ,r is the transmit rate in messages/sec) (optional ,f is schedule frequency, default is 100)

-c count

stop or reopen after this many msgs are processed

-t interval

stop or reopen after this amount of time has passed

-1 [+-]value

replace, set (+), or clear (-) user1 to this value

-2 [+-]value

replace, set (+), or clear (-) user1 to this value

-k cmd

make -c, -t continuous, run cmd on each new file (cmd can be empty if you just want the continuity)

-Dmod[,args]

add module

-H [sd]

hide source and/or destination IP addresses

argument to -l and -s can be addr/port or addr/port..port (range)

Examples

Common usage:

    $ ncaptool -t 3600 -k gzip -i enp9s0+ -o $FILE

to inspect a compressed ncap file, run something like this:

    $ zcat $FILE | ncaptool -n - -vmg -