kianmeng / sniffnet Goto Github PK

• Install

• Command line options

• User interactions during application execution

• Graphical report structure

• Textual report structure

• Supported application layer protocols

• Implementation details

• Error conditions

  • Wrong command line options specification
  • Pcap permission denied error
  • Windows configuration problems
  • Linux configuration problems
  • Textual report contains just the header

• Contribute

The graphical report consists of a svg file, constantly updated while sniffnet is running. It is suggested to open this file with a web browser, in order to be able to comfortably refresh it.

It reports the amount of sent (outgoing) and received (incoming) bits and packets per second.

Note that the number of bits and packets in the graph refers to one single second even if the update frequency is different.

The default update frequency is set to 5 seconds, but you can change it launching the application with the -i option. Note that the default interval of 5 seconds is more suitable if the network traffic is constant and steady (e.g., large file download); in case of intermittent traffic, you can consider using a lower time interval.

The first section of the textual report contains a header summarizing different useful information.

First, it specifies the name of the network adapter analyzed during the sniffing process.

Then there is a detail about the initial timestamp of the sniffing process, the last timestamp in which the report was updated, and the number of times the report was updated (re-written from scratch with updated data).

It also describes the status of the possible filters applicable by the user through the command line: IP address version, transport layer protocol, port minimum and maximum number, and application layer protocol.

Finally, it reports some statistics about the observed traffic: the number of [address:port] pairs considered, the total number of sniffed packets, the number (and percentage) of packets selected according to the active filters and a list of the observed application layer protocols with the respective packets count.

The second section of the textual report is dedicated to the packets stream analysis for each [address:port] pair.

This analysis results in a list in which each element represents an [address:port] pair with the relative statistics.

Note that such list of elements is sorted in descending order of exchanged packets.

For each element it is reported the amount of exchanged data measured in number of packets and in number of bytes between the source (on the left) and the destination (on the right).

For each [address:port] pair are reported the first and the last timestamp in which a packet was transmitted between that [address:port] pair.

Level 4 and level 7 carried protocols are also described (respectively transport layer and application layer protocols); please note that application level protocols are just inferred from the transport port numbers.

The application consists in three different execution flows.

The main thread waits for eventual user actions (by putting the terminal in raw mode through the crossterm::screen::raw::into_raw_mode() function and creating a crossterm::SyncReader which allows to read the input synchronously); in doing so it signals to the secondary threads when to pause or resume their work. The signaling is made possible by setting an application status, shared with the secondary threads and associated to a mutex and a condition variable.

The main() function, entry point of program execution, generates two secondary threads: one is in charge of waiting for network packets and parsing them, while the other is in charge of updating the textual and graphical reports every interval seconds (with interval defined by the user through the -i option; if omitted it's equal to 5 seconds).

The thread in charge of parsing packets also insert them into a shared map, where the key part is represented by an AddressPortPair struct and the value part is represented by a InfoAddressPortPair struct. Before parsing each packet it checks the application status: if it is Status::Pause it waits, otherwise it proceeds parsing the packet. This thread waits for packets without consuming CPU resources through the pcap::Capture::next_packet() method.

The thread in charge of updating the textual and graphical reports sleeps for interval seconds and re-writes the reports with updated traffic statistics.

• Not existing adapter name: if a non-existing adapter name is provided, the application raises an error and terminates. In this case the application will suggest using the -d option to print on the standard output a list of the available devices. sniffnet -d prints a list of all the available network adapters names and addresses, as in the example that follows.

• Invalid application layer protocol filter: if an invalid string is provided the application raises an error and terminates. The list of the supported application layer protocols is available in this section. Note that not including the --app option is equal to provide --app "no filter".

• Invalid highest port number: if the provided highest port number is not an integer in the range 0..=65535 the program raises an error and terminates. If also the lowest port number is specified and highest_port < lowest_port == true the program raises an error and terminates.

• Invalid interval value: if the provided interval value is not an integer in the range 1..=u64::MAX the program raises an error and terminates.

• Invalid lowest port number: if the provided lowest port number is not an integer in the range 0..=65535 the program raises an error and terminates. If also the highest port number is specified and highest_port < lowest_port == true the program raises an error and terminates.

• Invalid minimum packets value: if the provided minimum packets value is not an integer in the range 0..=u128::MAX the program raises an error and terminates.

• Invalid network layer protocol filter: if a string different from "IPv4", "IPv6" or "no filter" is provided (not case-sensitive), the application raises an error and terminates. Note that not including the -n option is equal to provide -n "no filter".

• Already existing output folder: there is no particular limitation on the output folder name. However, if the provided name corresponds to an already existing directory of your PC, keep in mind that the directory will be deleted and overwritten.

• Invalid transport layer protocol filter: if a string different from "TCP", "UDP" or "no filter" is provided (not case-sensitive), the application raises an error and terminates. Note that not including the -t option is equal to provide -t "no filter".

You may incur in this error if you have not the privilege to open a network adapter. Full error is reported below.

To solve this error you can execute the following command: sudo chown username /dev/bp*

Where username can be retrieved with the command whoami

Alternatively, you can run the application as root: sudo sniffnet [OPTIONS]

In both cases you will be requested to insert your system password.

In order to build and run Sniffnet you need to:

• Install Npcap.

• Download the Npcap SDK.

• Add the SDK's /Lib or /Lib/x64 folder to your LIB environment variable.

In order to build and run Sniffnet, install the libraries and header files for the libpcap library. For example:

On Debian based Linux: install libpcap-dev.

On Fedora Linux: install libpcap-devel.

Note that if you are not running as root, you need to set capabilities like so: sudo setcap cap_net_raw,cap_net_admin=eip path/to/bin.

If the textual output is not reporting packets statistics, make sure you are sniffing the correct network adapter (use the -d option to see the full list of your network adapters' names and addresses). To inspect a network adapter of your choice, remember to specify the -a option followed by the name of the adapter to be analyzed. If you don't include such option a default adapter is chosen by the application, but it may not be the one you expected to sniff.

Note that to see report updates while sniffnet is running you may have to close and re-open the report file.

If you are still not able to see any packet statistic, then it probably means that you are just not receiving packets from the network: surf the web to receive some packets.