In case of Ethernet header we will have destination Mac address and Source Mac Address.
In case of 802.11 packets there is at minimum three Mac addresses and in some cases 4 Mac addresses.
How is 802.11 packet formed using 802.3 packet? I know that native wifi is doing conversion in case windows. I want to know how it is achieving?
"How is 802.11 packet formed using 802.3 packet?"
The conversion (between 802.3 and 802.11 MAC frames) happens at link layer. The implementation details are platform and driver-dependent.
An example of how these are done in Linux kernel (using soft-MAC 802.11 driver):
http://lxr.free-electrons.com/source/net/wireless/util.c#L412
http://lxr.free-electrons.com/source/net/wireless/util.c#L530
Related
I have developed Xilinx Zynq SoC c program for transmitting customized raw ethernet packets for testing purpose.
When I connect the Zynq SoC board with a patch cable to the Desktop I get the following packet on Wireshark.
WireShark Packet Screen Capture
But when I bring a switch in between the two i.e. Zynq SoC connected to the switch and Desktop connected to the same switch the above packet sent from Zynq SoC isn't visible on Wireshark.
Can someone point me out what's wrong in the packet I am sending that makes the switch reject the packet I am sending.
I would like to mention that the zynq board doesn't transmit any packets except from the above.
Thanks
I have a Windows 7 machine with 3 Ethernet interfaces.
I created a UDP Socket and bound to INADDR_ANY. When the socket receives a broadcast UDP packet, how to know which network interface received the packets?
I need to get IP address corresponding to the network interface also?
Check out Wireshark:
https://www.wireshark.org/
From Wireshark about their product:
"Wireshark is the world's foremost network protocol analyzer. It lets you see what's happening on your network at a microscopic level. It is the de facto (and often de jure) standard across many industries and educational institutions."
I am a developer of WinPcap, a famous packet capturing and sending software under Windows. I have ported WinPcap to NDIS 6 Light-Weight Filter technique, but it still doesn't support loopback packets (such as packets sent to and received from 127.0.0.1) capturing because of Windows' nature: The loopback packets are handled directly in TCP/IP stack and don't go down to NDIS layer.
Someone told me that Windows Filtering Platform can see the loopback traffic, so I have done some research about it. I have several questions about this.
1) What are actually loopback packets? I mean the packets NDIS can't see? Like when I ping 127.0.0.1, these ICMP packets are definitely loopback ones. When I ping an address that a local network adapter has bound to (like 192.168.0.24), it is also loopback I think. Are these all conditions? If yes, then I can filter out which packets are loopback ones based on whether their local IPs are 127.0.0.1 or local adapter IPs (like 192.168.0.24).
2) I learnt that WFP has many layers, I think my requirement should use the "IP Packet (Network Layer)", I wonder that can WFP Network Layer captures all loopback packets inbound and outbound?
3) I don't know if the loopback packets captured by WFP will have an Ethernet header? If not, then I think I should manually add Ethernet header to the packet prefix before sending them to user mode, as WinPcap is an ethernet-level packet capture software and many software using WinPcap (like Wireshark) will by default parse the packets from Ethernet layer. However, I think I will let the whole Ethernet header to be all-0, as there's actually no Ethernet header in fact.
Thanks and appreciated for your help!
By using OID_802_3_PERMANENT_ADDRESS, I can query the mac address of an ethernet card. Intuitively, I think there should exist corresponding OID_802_11_PERMANENT_ADDRESS. However, I find none.
If I direct use OID_802_3_PERMANENT_ADDRESS to query the mac address of 802.11, the result seems correct.
So my question is: Are the mac addresses of 802.3 and 802.11 the same in their respective specifications?
Although the Media Access Control for the Ethernet and wireless link layers are very different due to the nature of collision detection, to keep things simple for the Internet protocols, the MAC address – regardless of the link layer – is always a globally unique 48-bit number. This is significant for Ethernet and 802.11 since routers often aggregate devices onto a single subnet.
So to answer your question, the MAC addresses will not be same.
How to real time convert wireless packet(802.11) to Ethernet packet(802.3) in windows?
I'm receive wireless packet with Wireless Lan.
I want forward this packet to Ethernet.
Can i do this work?
You're trying to do network bridging. Windows has this support built in starting with XP. This will make your computer into a very expensive two port Ethernet switch (where the wireless link is a port).
If you want to do some more fancy filtering, I suggest using a TUN/TAP driver or pcap/WinPCAP, which will allow you to receive raw frames.