# sniffnet (network packets sniffer/filter)
[](https://github.com/Crirock/pdsproject/actions/workflows/rust.yml)
[](https://crates.io/crates/sniffnet)
Aim of the application is to intercept and filter network traffic through a user specified interface of a computer.
The application will periodically generate and update a [human-readable textual report](#textual-report-structure), providing statistics about the observed network packets.
Several command line options are available to select the network adapter to inspect, to set a desired report update frequency and to specify filters on the observed traffic.
<hr>
<details>
<summary>Table of contents</summary>
- [Install](#install)
- [Command line options](#command-line-options)
- [User interactions during application execution](#user-interactions-during-application-execution)
- [Textual report structure](#textual-report-structure)
+ [Report header](#report-header)
+ [Report [address:port] list](#report-addresses-list)
- [Supported application layer protocols](#supported-application-layer-protocols)
- [Implementation details](#implementation-details)
- [Error conditions](#error-conditions)
+ Wrong command line options specification
+ Pcap permission denied error
+ Windows configuration problems
+ Linux configuration problems
+ Textual report contains just the header
+ Other errors
- [Authors](#authors)
</details>
<hr>
## Install
The application binary can be installed with ```cargo install sniffnet```
The application can then be run using ```sniffnet [OPTIONS]```
## Command line options
- **-a, --adapter**:
specifies the name of the network adapter to be inspected; if omitted the default adapter is chosen.
- **--app**:
filters packets on the basis of the provided application layer protocol.
- **-d, --device-list**:
prints list of the available network interfaces. Immediately terminates the program.
- **-h, --highest-port**:
specifies the maximum port value to be considered; if omitted there is no ports higher bound.
- **-i, --interval**:
sets the interval of time between report updates (value in seconds).
- **-l, --lowest-port**:
specifies the minimum port value to be considered; if omitted there is no ports lower bound.
- **-m, --minimum-packets**:
sets the minimum value of transited packets for an [address:port] to be printed in the report.
- **-n, --net**:
filters packets on the basis of the provided IP address version (IPv4 or IPv6).
- **-o, --output-file**:
specifies the name of output file containing the textual report; if omitted the file name is ```sniffnet_report.txt```
- **-t, --trans**:
filters packets on the basis of the provided transport layer protocol (TCP or UDP).
## User interactions during application execution
The user can interact with the sniffing process through the terminal window.
- **Pause**: to temporarily pause the sniffing process, the user can type a 'p' character in the terminal window.
- **Resume**: to later resume the sniffing process, the user can type a 'r' character in the terminal window.
- **Stop**: to stop the application execution, the user can type a 's' character in the terminal window.
## Textual report structure
In this section is reported the structure of the output report file generated, to help the users better understand and interpret it.
### Report header
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.
### Report addresses list
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.
## Supported application layer protocols
<details>
<summary>See details</summary>
| 20, 21 | FTP |File Transfer Protocol |
|22|SSH |Secure Shell |
|23|Telnet |Telnet |
|25|SMTP |Simple Mail Transfer Protocol |
|49|TACACS |Terminal Access Controller Access-Control System |
|53|DNS |Domain Name System |
|67, 68|DHCP |Dynamic Host Configuration Protocol |
|69|TFTP |Trivial File Transfer Protocol |
|80, 8080|HTTP |Hypertext Transfer Protocol |
|109, 110|POP |Post Office Protocol |
|123|NTP |Network Time Protocol |
|137, 138, 139|NetBIOS |NetBIOS |
|143, 220|IMAP |Internet Message Access Protocol |
|161, 162, 199|SNMP |Simple Network Management Protocol |
|179|BGP |Border Gateway Protocol |
|389|LDAP |Lightweight Directory Access Protocol |
|443|HTTPS |Hypertext Transfer Protocol over SSL/TLS |
|636|LDAPS |Lightweight Directory Access Protocol over TLS/SSL |
|989, 990|FTPS |File Transfer Protocol over TLS/SSL |
|993|IMAPS |Internet Message Access Protocol over TLS/SSL |
|995|POP3S |Post Office Protocol 3 over TLS/SSL |
|1900|SSDP |Simple Service Discovery Protocol |
|5222|XMPP |Extensible Messaging and Presence Protocol |
|5353|mDNS |Multicast DNS |
</details>
## Implementation details
<details>
<summary>See details</summary>
The application consists in three different execution flows.
The main thread waits for eventual [user actions](#user-interactions-during-application-execution) (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 report 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 ```AddressPort``` struct and the value part is represented by a ```ReportInfo``` 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()``` function.
The thread in charge of updating the textual report sleeps for ```interval``` seconds and re-writes the report with updated traffic statistics.
Before updating the report it checks the application status: if it is ```Status::Pause``` it waits, otherwise it proceeds writing the report.
</details>
## Error conditions
<details>
<summary>See details</summary>
### Wrong command line options specification
- **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](#supported-application-layer-protocols) 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"```.
- **Invalid output file extension**:
there is no particular limitation on the output file name.
However, if an invalid file extension is provided the file may result unreadable if the extension is not subsequently removed.
- **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"```.
### Pcap permission denied error
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.
### Windows configuration problems
In order to make pcap work properly on Windows systems, it is needed to download [WinCap](https://www.winpcap.org/install/) and the [WinPcap Developer's Pack](https://www.winpcap.org/devel.htm) and to add the ```/Lib``` or ```/Lib/x64``` folder to the ```LIB``` environment variable.
### Linux configuration problems
To correctly use pcap on Linux systems, 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```.
### Textual report contains just the header
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.
### Other errors
Other errors, not previously listed, may occur seldom.
Most of such errors are due to the unwrapping of ```Result<T>```, which may exceptionally contain the ```Err``` value.
This may happen in one of the following situations: activation of a pcap ```Capture``` handle, retrieval of network adapters list through pcap, selection of the default device through pcap, creation of the output file, cloning of the output file handle, acquisition of a ```Mutex``` lock, writing of the output file.
All those exceptional scenarios are managed through calls to the ```expect()``` method, providing textual feedback to the user on the cause of the panic.
The ```unwrap()``` method is used only on ```Option<T>``` values when it's certain they contain ```Some``` value.
</details>
# Authors
- [Bellini Giuliano](https://github.com/GyulyVGC)
- [Canepari Cristiano Marco](https://github.com/Crirock)