Module netlink

Low-Level Netlink Interface

Purpose

This module provides functions to query the Linux kernel’s networking subsystems via netlink sockets. It is used to fetch information such as network interface details, IP addresses, routes, and neighbor (ARP) entries.

How it works

It communicates with the kernel using a raw NETLINK_ROUTE socket. The netlink-packet crates are used to construct, serialize, and deserialize netlink messages. A generic netlink function handles the common pattern of sending a request and processing a potentially multi-part response. Specific functions like get_ipv4_routes and get_neighbors use this generic handler to fetch and parse different types of data.

Main components

• netlink(): A generic function for the netlink request/response message loop.
• get_links(), get_ipv4_routes(), get_neighbors(), get_ipv4_address(): Public functions for querying specific kernel data.
• Link, Ipv4Route, Neighbor: Structs that represent the networking objects retrieved from the kernel.

Structs

Gateway

Represents a default gateway.

Ipv4Route

Represents an IPv4 route.

Link

Represents a network interface link.

Neighbor

Represents a neighbor (ARP) entry.

Functions

find_default_gateway

Finds the default gateway from a list of IPv4 routes.

get_ipv4_address

Retrieves IPv4 addresses associated with network interfaces.

get_ipv4_routes

Retrieves a list of IPv4 routes from the kernel.

get_links

Retrieves a list of all network interfaces (links) from the kernel.

get_neighbors

Retrieves a list of neighbor (ARP) entries from the kernel.

netlink

A generic function to send a netlink request and parse the response.