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Andrea Vaccaro edited this page Jan 5, 2024 · 16 revisions

Usage of Gapcast

With ./gapcast -h

Usage of gapcast:

Interfaces & band misc:
   -show-i
        Shows available network interfaces.
   -i <interface> : string
        Select network interface.
   -5g
        Start with 5 Ghz band.
   -2.4+5g
        Start with 2.4/5 Ghz band.

Filter misc:
   -c <channel> : int
   -c <channels> : int,int,int...
        Select working channel.
   -b <BSSID> : string
        Select BSSID filter.
   -p <BSSID PREFIX> : string
        Select BSSID prefix filter.
   -beacon
	Shows only beacons.
   -d
        Disable inactive devices hider.
   -radar
        Enable RadarRSSI.

Work with pcap:
    -w <file>.pcap
        Write to pcap file.
    -l <file>.pcap
        Load pcap file.

Description & explanations

Gapcast is an IEEE 802.11 packet injection and analyzer software.

The purpose of gapcast is to accurately detect each router's clients, analyze, capture and inject packets. Gapcast adds more and more parameters for filters and functionality during releases. Gapcast therefore requires good documentation to use the software to its fullest.

Supported platform: GNU/Linux, Windows 8.1+

Parameters

  • -show-i  Shows available network interfaces.
  • -i            Select network interface.
  • -5g         Start with 5 Ghz band.
  • -2.4+5g  Start with 2.4/5 Ghz band.
  • -c           Select working channel.
  • -b           Select BSSID filter.
  • -p           Select BSSID prefix filter.
  • -beacon Shows only beacons.
  • -d           Disable inactive devices hider.
  • -radar     Enable RadarRSSI.
  • -w          Write to pcap file.
  • -l            Load pcap file.

--show-i

The -show-i parameter is used to show all the available network interfaces by attaching the mac addresses. It is used to suggest the network interface to use in the -i parameter with the name

Syntax:

-show-i

Example:

./gapcast -show-i

-i

The -i parameter is used to select the network interface that gapcast will use. Gapcast will check during initialization to make sure that monitor mode is enabled on the network card, so it is important to insert a network interface that supports it.

Syntax:

-i <interface>

Example:

./gapcast -i wlan0

./gapcast -i "Wi-Fi 2"

-5g

The -5g parameter is used to select the work band, some channels between 36 and 173 (line 19 from gapcast/libs/libs.go).

If it is not specified the default band is 2.4 Ghz, from channel 1 to 14 (line 18 from gapcast/libs/libs.go).

Syntax:

-5g

Example:

./gapcast -i wlan0 -5g

-2.4+5g

The -2.4+5g parameter is used to select the work band, some channels between 1 and 173 (line 20 from gapcast/libs/libs.go).

Syntax:

-2.4+5g

Example:

./gapcast -i wlan0 -2.4+5g

-c

The -c parameter is used to select the work channel, you can select 1 or more channels that gapcast will scan.

If it is not specified the default band is 2.4 Ghz, from channel 1 to 14 (line 18 from gapcast/libs/libs.go).

Syntax:

-c <channel>

-c <channel,channel,channel...>

Example:

With 2.4 Ghz:

./gapcast -i wlan0 -c 4

./gapcast -i wlan0 -c 5,12,7,3

With 5 Ghz:

./gapcast -i wlan0 -5g -c 36

./gapcast -i wlan0 -5g -c 50,100,60,126

With 2.4/5 Ghz:

./gapcast -i wlan0 -2.4+5g -c 2,6,132,7,40

-b

The -b parameter is used to filter the bssid, to use this parameter you must first specify a single channel. The bssid must be written separated between ":" as in the example.

Syntax:

-b <BSSID>

Example:

./gapcast -i wlan0 -c 12 -b 70:4e:24:d3:f2:9b

./gapcast -i wlan0 -5g -c 36 -b 90:a2:57:b1:f4:f3

-p

The -p parameter is used to filter the BSSID with a prefix. All BSSIDs with that prefix will be shown.

Syntax:

-p <BSSID PREFIX>

Example:

./gapcast -i wlan0 -p 70:4e:24:d3:f2:9

./gapcast -i wlan0 -2.4+5g -p 23:5

-beacon

The -beacon parameter is used to show and record beacon packets only.

Syntax:

-beacon

Example:

./gapcast -i wlan0 -2.4+5g -beacon

./gapcast -i wlan0 -beacon -c 10 -radar

-d

The -d parameter is used to disable shifting of inactive devices. More info.

Syntax:

-d

Example:

./gapcast -i wlan0 -p 80:3e:3 -d

./gapcast -i wlan0 -2.4+5g -d

-radar

The -radar parameter is used to enable RadarRSSI.

This library has an Auto-DBPathLoss system where the Path Loss is chosen via an algorithm, it was created through research and has been tested many times with excellent results.

For power dBm, antenna dBi, these parameters are editable on the radarconf.json file

Syntax:

-radar

Example:

./gapcast -i wlan0 -5g -radar

./gapcast -i wlan0 -c 13 -b 70:12:a3:f8:e4:36 -radar

-w

The -w parameter is used to record and write all the filtered packets in a pcap file, it can be important both for subsequently doing a load or for saving the EAPOL keys.

Note The -d and -radar parameters do not affect writing of the pcap file.

Syntax:

-w <file>.pcap

Example:

./gapcast -i wlan0 -5g 36 -b 32:4e:24:14:f2:9e -w out-eapol.pcap

./gapcast -i wlan0 -2.4+5g -w out1.pcap

-l

The -l parameter is used to load a pcap file and restore data, can you continue scan by adding -i.

If you want to update a pcap file, then load it and scan it, with the information from the previous pcap file and the new information, just set both -w and -l. More info.

Note The -d and -radar parameters do not affect writing of the pcap file.

If you had previously specified these parameters they will not have any effect on the load, the RadarRSSI data will not be loaded and inactive devices will be loaded automatically.

Syntax:

-l <file>.pcap

Example:

./gapcast -l out.pcap

./gapcast -l out.pcap -i wlan0

./gapcast -i wlan0 -2.4+5g -c 10,50,36,2,172 -w updated.pcap -l out.pcap

Examples and more detailed explanations can be found on the main page.

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