tuntap | Native Go Wrapper for TUN/TAP devices on Linux and Mac OS X | iOS library

As a personal project I want to build a TCP/IP stack using C/C++ and using a tap interface. I have a wlan0 interface (wireless) that is connected to the internet. And now I want to send and receive packets from the internet through this wlan0 interface.

How can I do this?

These are the commands I used to create my tap interface:

I am learning routing with tuntap interfaces... and I had created a tun0 interface and configured Ip address with ifconfig command on different subnet and adding the gateway with ip route command and I have also used masquerading rule ... my doubt is can i ping with tuntap interface or they are only used to route the traffic or something I don't know about these interface or may be misconfiguration..

May be this question sounds me new bie and I am but give please give me correct direction..

Ok Gerhardh,

Edit: I had created tun dev like this:

I have an application that creates, listens on and writes to a tap interface. The software will read(tun_fd,...) and perform some action on that data, and it will return data to the system as UDP packets via write(tun_fd,...).

I assign an IP to the interface, 10.10.10.10\24 so that a socket application can bind to it and so that the kernel will pass any packets for the virtual subnet to the tap interface.

The software generate frames with IP/UDP packets with the destination IP being that assigned to the interface, and a source IP existing in the same subnet. The source and dest mac address match that of the tap device. Those frames are written back to the kernel with write(tun_fd,...).

If I open said tap interface in wireshark I will see my frames/packets as I expect to, properly formatted, expected ports, expected macs and IPs. But if I try to read those packets with netcat -lvu 0.0.0.0 ${MY_UDP_PORT} I don't see anything.

Is this expected behavior?

Update 1

INADDR_ANY is a red herring. I have the problem even when explicitly binding to an interface / port as in this pseudo code:

I have been working on a program which uses a TUNTAP interface (in TUN mode) on a routing device which runs on top of the Linux kernel. It is a multicast tunneling protocol, and I am trying to send MLD joins to the kernel through my application so it can be recieved elsewhere. However, even though I have quadruple-checked my packets being sent on the interface, the linux kernel is dropping the packet before it gets passed on.

Tediously I have been tracing the path of the packet through the linuxkernel trying to figure out why it is being dropped and I think I have figured out to some extent why it is not being processed. The Hop-by-Hop options (containing the Router-Alert option which is necessary for MLD) is being parsed in net/ipv6/ip6_input.c in the ipv6_rcv function, but instead of continuing to process the packet in ip6_rcv_finish, the packet is dropped since the NF_HOOK at the end of the ipv6_rcv function is somehow interpreting the packet as being processed by something else. (NF_STOLEN instead of NF_ACCEPT)

Once the ipv6_rcv function finishes executing, something else executes ip6_mc_input, (in net/ipv6/ip6_input.c still) but from here the Hop-by-Hop options are not processed, which means when the kernel ends up processing the Layer-4 protocol, it has nothing to handle the protocol since the Hop-by-Hop options were meant to be processed beforehand. This means that the kernel drops the packet due to an unknown protocol.

What I am trying to figure out is what is calling ip6_mc_input. I have looked quite a bit on elixir for what could call it, but there are so many possibilities since it is called from a pointer in a rt6_info struct which is difficult to trace since so many things use it. Does anyone know anything that could help me in my search?

IGMP joins work fine, but the IPv4 stuff is probably quite similar so information from that context would probably be helpful too.

For reference, the linux kernel version in use is v4.4.6