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Questions tagged [netlink]

Netlink is a socket based inter process communication protocol for Linux systems. It is currently the preferred way, as of 2.6, of communicating with user space from the kernel.

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Manage Linux routing rules using RTNETLINK

I'm trying to write a small C based user space app that provides feature of managing routing rules using RTNETLINK. Below is an example accepting 3 arguments: add/del (rule), IP address and iface. The problem with code below that it adds routing…
Ogy89
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Linux carrier detection notification

Is there an interface in Linux to get notification of a network interface carrier change? I know its possible to poll an interface with SIOCETHTOOL, but was wondering if there was any way to get notified or any blocking calls that would return on…
tMC
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linux c rtnetlink RTM_GETADDR ignores ifa_index in struct ifaddrmsg and instead outputs for all interfaces

When sending a "packet" to a rtnetlink socket to get the IP addresses of a specific interface then it answers with what appears to be data for all interfaces. This is a small example program that illustrates my problem: #include #include…
Alexander Schütz
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how to get qdisc plug state (buffered or released)?

I have two network namespaces (red at 192.168.15.1 and blue at 192.168.15.2) connected by a virtual ethernet cable. Red side, the device is named veth-red, blue side, it is named veth-blue. Now i want to add a "plug" qdisc to veth-blue, I'm doing it…
MatMo
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Audit netlink response don't have the right packet length

I have been trying to read the linux audit logs from go using mdlayher/netlink. I am able to make a connection and set the PID as well to be able to receive logs from the netlink socket over unicast and multicast. The problem is, when the library…
prateeknischal
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How to get WiFi security key(WPA, WPA2, ESS) of scanned networks using NL80211_BSS_CAPABILITY?

I'm using netlink library nl80211.h to scan wifi networks and successfully getting ssid, mac address, status, frequency and signal. I want to add security type of every network using same library. I'm using NL80211_BSS_CAPABILITY as one of the enums…
iambhaskaranand
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is netlink synchronous or asynchronous protocol?

I was reading various resources about netlink, and they all say that the netlink communication protocol is asynchronous (example: https://www.opensourceforu.com/2015/08/netlink-a-communication-mechanism-in-linux/), however this confuses me: I think…
Mark
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Request list of attached devices from netlink socket

I am working on a C++ application for embedded devices that listens to USB hotplug events via a netlink socket. Detecting events works flawlessly but additionally I would like to query already attached devices in the beginning of the program. I was…
teawolf
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How to reliably detect dropped netlink requests or responses

I'm interested in using netlink for a straightforward application (reading cgroup stats at high frequency). The man page cautions that the protocol is not reliable, hinting that the application needs to be prepared to handle dropped…
jacobsa
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Fetch dropped packet count of an interface with netlink sockets

I am familiar with different tools (like netstat, tcpdump, etc.) and files (like /sys/class/net//statistics) with which we can get the count. But can anyone tell me if there is a way of getting that information directly from the kernel, using…
Dusan
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Why the route items in the route table(fetched via netlink socket) doesn't have netmask info?

I'm writing a program to find out which network interface is the best to connect to a specified target address. Right now, I can get the route table via netlink socket APIs, but seems there is no netmask infos in it. I read the manual of…
Chao Zhang
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Why does Linux NETLINK man page provide C++ examples but not C?

I dealt with netlink API and examine its man pages netlink(3) and netlink(7). Suddenly I faced with such construction: struct msghdr msg; msg = { &sa, sizeof(sa), &iov, 1, NULL, 0, 0 }; I tried it in C, but it gives the error: error: expected…
z0lupka
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get process inode using netlink

I want to try and correlate an IP packet (using libpcap) to a process. I have had some limited success using the relevant /proc/net/ files but found that on some of the machines i'm using, this file can be many thousands of lines and parsing it is…
incubus
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Kernel to userspace application communication

I am trying to make Kernel (Android, kernel 4.9.59) communicate with userspace applications. I found a solution using Netlink sockets: https://stackoverflow.com/a/25071310/4190159 The first issue with the solution is that struct netlink_skb_parms…
Somdip Dey
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Obtaining real device of VLAN-interface through the netlink

I need to obtain the real_dev (f.e. ID) of the given VLAN-inteface. I wrote some test snippet using libnl: int main(void) { struct nl_sock *sock; struct nl_cache *cache; char iface[] = "eno1.10"; //char iface[] = "eno1"; if…
red0ct
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