---
name: "guessnet-scan"
section: "8"
platform: "linux"
package: "guessnet"
version: "0.56+b2"
release: "Debian 11 (Bullseye)"
platforms: ["linux"]
url: "https://new.carta.tech/guessnet-scan"
---

# guessnet-scan(8)

guess network configuration data by looking at network traffic

## NAME

guessnet-scan - guess network configuration data by looking at network traffic

## SYNOPSIS

**guessnet-scan** \[*options*\] \[*ethernet\_interface*\]\

## DESCRIPTION

**Guessnet-scan** tries to deduce network configuration data by watching network traffic at a given Ethernet interface.

After scanning network traffic for some time, **guessnet-scan** prints a configuration string suitable for inclusion in /etc/network/interfaces.

Note that **guessnet-scan** uses heuristics and wild guesses and that the resulting data is not guaranteed to be accurate. The program is intended to be used as a first try at getting network configuration data without bothering anyone.

## OPTIONS

Options follow the usual GNU conventions,

- **--debug**

  Print debugging messages.

- **--help**

  Show a brief summary of commandline options.

- **--init-time**=*int*

  Time in seconds to wait for the interface to initialize when it is not found already up at program startup. Default: 3 seconds.

- **-t**, **--timeout=*int***

  Time in seconds to watch for network traffic. Default: 5 seconds.

- **-v**, **--verbose**

  Operate verbosely.

- **--version**

  Show the version number of the program.

## SCANNING REQUIREMENTS

To correctly identify all data of the local network, **guessnet-scan** needs to see traffic related to a host in the local network and to the local gateway, if any.

To be able to identify the network gateway, **guessnet-scan** also needs to see some traffic directed to the external network: you can help the detection by generating some outbound IP traffic during the scan, for example by browsing a web page (without proxy) or using telnet to open a connection to some remote host.

Note that if you are connected to a switch, **guessnet-scan** won't probably be able to work, since the switch will isolate it from the network traffic that the other machines are generating.

## SEE ALSO

[**guessnet**(8)](/guessnet/8.md), [**interfaces**(5)](/interfaces/5.md).

## AUTHOR

**Guessnet-scan** was written by Enrico Zini \<enrico@debian.org\>.