### Tool 7: Sniff

### Description:

      This tool captures network packets. It can display them, or save them
      in a file (named 'record' in netwox).

      Parameter --device indicates on which device to sniff. Please note
      that under some systems, such as Windows, sniffing on some devices is
      not supported.
      Parameter --filter defines the sniff filter. It permits to restrict
      captured packets. This kind of filter is named a BPF or pcap filter.
      Basic elements of a filter are:
        host 1.2.3.4
        net 192.168.10
        net 192.168.10.0 mask 255.255.255.0
        net 192.168.10.0/24
        port 21
        dst host 1.2.3.4
        src port 2345
        ether host a:b:c:d:e:f ('ether a:b:c:d:e:f' is not working)
        ether src aa:bb:cc:dd:ee:ff
        ip
        arp
        rarp
        tcp
        icmp
        udp
      Here are filter examples:
        "host 1.2.3.4"
        "net 192.168 and icmp"
        "host 1.2.3.4 or dst port 80"
        "(udp or tcp) and not host 1.2.3.4"
      Parameter --pause permits to press P (pause) or Q (quit) keys
      to pause or stop capture.
      Parameter --hdrencode and --dataencode defines how to display header
      and data/payload. Common useful values are: array, dump, synth,
      nothing, text. Full list is available through netwag or running tool
      12.
      Parameter --rawip indicates to ignore Ethernet/link layer, and start
      displaying at IP header.
      Parameter --extended indicates to try to decode other protocols such
      as DNS or DHCP.
      Parameter --ipreas tries to reassemble IP packets. This might miss
      packets.
      Parameter --tcpreord tries to reorder TCP flow (seqnum increments).
      This might miss packets.

      A record is a capture file. It contains several packets captured
      during a sniff. It can also be created by hand. There are 7 formats
      for records: pcap (tcpdump compatible), bin (binary, unreadable by
      humans but fast) and mixed/mixed_wrap/dump/hexa/hexa_wrap (easy to
      read and edit). A record also has an associated DLT (Data Link Type),
      indicating at which level a packet start: raw (start at IP header) and
      ether (start at Ethernet header) are the 2 most common DLT. Tool 13
      displays DLT of each device.
      Parameter --outfile indicates the name of file where to store captured
      packets. Parameter --recordencode defines how to encode data in this
      file (suggested values: bin, pcap and mixed_wrap). Capture can
      automatically swap file using parameters --split-size or --split-age.
      The DLT (Data Link Type) of packets in this record will be 'raw' if
      --rawip is set, otherwise the sniff DLT obtained by tool 13.

      This tool may need to be run with admin privilege in order to sniff.

### Synonyms:

capture, ethereal, frame, pcap, snoop, tcpdump

### Usage:

netwox 7 [-d device] [-f filter] [-p|+p] [-H encode] [-D encode] [-r|+r] [-x|+x] [-i|+i] [-t|+t] [-s|+s] [-o file] [-R recordencode] [-c uint32] [-C uint32] [-Q|+Q]

### Parameters:

parameter | description | example
`-d|--device device` | device name | Eth0
`-f|--filter filter` | pcap filter |
`-p|--pause|+p|--no-pause` | can pause |
`-H|--hdrencode encode` | header encoding type for screen | array
`-D|--dataencode encode` | data encoding type for screen | dump
`-r|--rawip|+r|--no-rawip` | sniff at IP level |
`-x|--extended|+x|--no-extended` | display other protocols | This boolean is set. Use + or --no- to unset it.
`-i|--ipreas|+i|--no-ipreas` | reassemble IP packets |
`-t|--tcpreord|+t|--no-tcpreord` | reorder TCP packets |
`-s|--screen|+s|--no-screen` | display to screen | This boolean is set. Use + or --no- to unset it.
`-o|--outfile file` | save in record file | dstfile.txt
`-R|--recordencode recordencode` | encoding type for record file | bin
`-c|--split-size uint32` | maximum size of record in kb | 0
`-C|--split-age uint32` | maximum age of record in seconds | 0
`-Q|--losepriv|+Q|--no-losepriv` | lose privileges to nobody user under Linux |

### Example:

netwox 7