You are also right that when I send broadcast frames to my “test” bridge, the frames get to both tap0 and tap1. Strangely, I can’t make it work on Ubuntu Do you have any ideas on how to make UDP more reliable? Hence my comment that perhaps the utility could check for the existence of the interface before calling the above function straight away although, on second thought, that would be racy and effectively useless in practice. You need to have a program running on b listening on port like simpletun in “server” mode and try to connect from a. Something that i missed in this tutorial and that i wanted to know is.. Anyone seen this, or have a guess as to what the issue would be?

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Glad you finally solved it! So, how does your application connect to the tun1 interface descriptor, and how do you actually read the packets?

Since ip tables is only aware of the network layer, would iptables discard it or let it pass? July 18, at But the kernel has otherwise ignored the IPv6 pings!

Natural Born Coder

I was trying to create two tap interfaces, attach it to a linux bridge, send frame via one tap interface and hoping to receive from the other tap interface. Under Linux, the bridge interface automatically takes the lowest MAC address of all the enslaved interfaces see this article for more information on the implications of this. I’m not sure I understand, but I don’t think changes to ports in the control plane kinux “propagate” via TCP to the data plane, unless you implement it yourself.


Then I am then performing some activities such as filtering packets and performing some deep packet inspection.

So I will have this architecture 3 machines: Hi Waldner, thanks for all of this information.

TUN/TAP Demystified –

Output for some coomands which may be of use are:. You can find some theory at http: Home Questions Tags Users Unanswered.

I’d like it to be up ie, to get the “carrier” without needing to see some process attached to the special fd so traffic can be sniffed regardless of the carrier state? In this case, All of this is exactly what User Mode Linux does: Now, for a change, I have a solution!! The difference is that the latter architecture describes a connection between lxc containers and the host machine. I am trying to do something similar.

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Thanks a lot for immediate response. Is this a legitimate usage of tun at all? The problem I have is that once I exit this program that created the tap device ctrl-c or killI cannot ever get it to run again successfully without rebooting. As I am new to the networking stuff,I couldn’t understand why we are not able to capture frames for In the case of an error i think i should be able to detect it by comparing the IP-Packet-Size with the used space in receive buffer return value of read.


Of course, then you’ll have to manage contention yourself. Hi, I think there is something which is a bit wrong with the linux tun driver.

Understanding TUN TAP Interfaces – Natural Born Coder

The interface can be transientmeaning that it’s created, used and destroyed by the same program; when the program terminates, even if it doesn’t explicitly destroy the interface, the interfaces ceases to exist. I was replying to your observation that “ip tuntap del” huntap a non-existent tap interface does not produce an error. Is there something I am seriously overlooking here?

Is that meant to be the same variable? I am facing some issues while using tap interface over windows. I am doing exactly this: I tkntap usually, because there is one exception: Note that it’s entirely your code’s responsibility to create and correctly fill each and every header, field and checksum at the ethernet, IP and ICMP layers.

I tried to figure it out, but seems that ping -I tun0 send the data, but the program is waiting at nread. Sign up using Email and Password.