Common questions

What is Rtnetlink?

What is Rtnetlink?

Rtnetlink allows the kernel’s routing tables to be read and altered. It is used within the kernel to communicate between various subsystems, though this usage is not documented here, and for communication with user-space programs.

How do you make a netlink socket?

In user space, we call socket() to create a netlink socket, but in kernel space, we call the following API: struct sock * netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len)); The parameter unit is, in fact, the netlink protocol type, such as NETLINK_TEST.

What is generic netlink?

Generic netlink was designed to allow kernel modules to easily communicate with userspace applications using netlink. Instead of creating a new top level netlink family for each module, generic netlink provides a simplified interface to enable modules to plug into the generic netlink bus.

What is Netlink in Linux?

Netlink is a Linux kernel socket interface, which is used for inter-process communication between the user space and the kernel, and also between different user space processes. It reduces dependence on system calls, ioctls and proc files. Netlink also helps preserve kernel purity.

What is Netlink protocol?

The Netlink socket family is a Linux kernel interface used for inter-process communication (IPC) between both the kernel and userspace processes, and between different userspace processes, in a way similar to the Unix domain sockets.

What is Netlink message?

Netlink is used to transfer information between the kernel and user-space processes. It consists of a standard sockets-based interface for user space processes and an internal kernel API for kernel modules. NETLINK_W1 (Linux 2.6. 13 to 2.16. 17) Messages from 1-wire subsystem.

What is a routing socket?

A routing socket is a special type of socket that is not specific to any particular network protocol, but allows “privileged” user processes to write information into the kernel. User processes use this type of socket to add and remove information from the routing table.

How to use RTNetlink in Linux 2.2?

RTM_NEWTFILTER, RTM_DELTFILTER, RTM_GETTFILTER Add, remove, or receive information about a traffic filter. These messages contain a struct tcmsg as described above. rtnetlink is a new feature of Linux 2.2. This manual page is incomplete.

What are the message types in RTNetlink?

Messages Rtnetlink consists of these message types (in addition to standard netlink messages): RTM_NEWLINK, RTM_DELLINK, RTM_GETLINK Create, remove, or get information about a specific network interface.

How to manipulate the networking environment using RTNetlink?

The following sequence of socket calls have to be made when manipulating the networking environment through RTNETLINK: Open socket. Bind socket to local address (using process ID). Send message to the other end point. Receive message from the other end point. Close socket.

How is a request or a response filled in rtnetlink?

A request or a response of RTNETLINK consists of a stream of message structures. These structures are filled by the caller, in the case of a request, or filled by the kernel, in the case of a response. To place information into these structures or to retrieve information, RTNETLINK provides a set of macros (using #define statements).

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