I have a VM (installed Linux) and I want to make a raw socket that sends it to the computer, in Wireshark it says that the packet was sent but it didn't arrive. I saw that I should configure a bridge network adapter but I don't know anything about that except it connects between VM to host. When I configure this adapter, my mac, and IP change so what my packet fields would be?
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I'm trying to send a fake echo response to a virtual machine that is trying to ping an IP address from another virtual machine. When I send ping from the victim VM, the terminal output of the victim VM says that there were no packets received but I can see that the fake response packets are received using wireshark on the victim VM. I tried turning off the firewall but nothing changed. Are there any other security measures that I'm not aware of? (Both VMs are Ubuntu 16.04)
My ubuntu machine's wireless interface is connecting to the wireless router. I wrote a simple web server listening on port 8888. I would like to understand how the packets are sent and receive using localhost. So I did the following experiment:
I started wireshark on the same machine listening wlan0 and on the terminal I type:
$telnet localhost 8888
Then I observe TCP SYN, SYN/ACK, ACK. In these messages, the MAC src and dest addresses are all 00:00:00:00:00:00. The src and dst IP addresses are all 127.0.0.1.
Does this mean these packet never go out from my wlan0 interface to the wireless router and directly loop back within my machine? Does it even reach my wireless card or just looping back within the ubuntu linux OS?
The packets to localhost do NOT 'go out on wire'; i.e. the packets are send to receive buffers locally by the network driver.
IF you telnet to local server IP, then the packets do go out on wire. e.g. telnet 192.168.100.1 would make packets go out on wire.
I am trying to learn something about sockets in Linux. I have small development board something like raspberry Pi with Linux running inside. Unfortunatly it doesn't have ethernet or usb port.
I have created a dummy network interface and used it like default gateway. I have written a small program using raw sockets listening on dummy interface (then sends all packets over serial line to computer where is program which send this packets to the internet and recieves answers a sends them back).
My problem is when i am trying to ping some public IP address i can see in tcpdump the ICMP requests and responses in both computer and development board. But the ping looks like it does recieve nothing.
I have tryed to use loopback interface instead of dummy interface, but in this case the pings gets looped and the device becomes unresponsible in a while :). But the ping did recieve ICMP response, and TCP connection didn't work.
I also have tryed to use 2 dummy interfaces and create bridge.
I would be very grateful for any advices.
I am working on a C program on Linux (kernel 2.6.18). I need to send/inject IP packets (e.g., over a socket) in my Linux systems, but make the same Linux "think" that these packets are incoming from another host. I creat a datalink socket and use faked source mac/ip for the packets sent over this socket. The destination mac/ip are set to the ones in my local Linux. However, whether I send these packets in a user-space program or in a kernel module, my local Linux just doesn't think these packets are coming from outside. For example, if I create a datalink socket to send an ICMP request destined to my local Linux, I expect my local Linux to think this ICMP request coming from outside, and would respond with an ICMP reply, but my local Linux does not do so. (However, with the same program I can send a faked ICMP request to another host, and that host does respond an ICMP reply.)
I did some research on this topic online, and it seems all related solution suggest using TAP. But as this VirtualBox article says:
... TAP is no longer necessary on Linux with bridged networking, ...
I am very interested to know how this is possible. Thanks.
For the sake of simplicity, I will refer you to http://en.wikipedia.org/wiki/Berkeley_sockets and the UDP server and client source code there.
I am trying to send a packet using UDP protocol to a linux VirtualMachine server program. Both my host and VM ping well; all packets sent are received in both directions. However my server program is either not receiving any packets, or it is simply not printing. Either way, it isn't printing the confirmation or contents of any packets I send to it from the host.
I do not have another PC handy, but both programs communicate well enough if I stage them on the same computer and Wireshark reports that the packets are being sent.
Mine is a three part question: first, how can I fix this. Second, why would the host and VM receive each others ping messages, but not pass these on to the open sockets of both ends of my UDP system? Finally, do you have any suggestions about the form or intent of this question?
EDIT: I've tried running my VM with the NAT and bridged adapter network setups. However, I can't conceptualize the relationship between those setups and my problems right now.
With NAT networking, the VM gets a private IP address (usually 192.168.x.y) and the host does NAT translation of outgoing packets, and translates reply packets back to the VM. In this mode, all communication must be initiated by the VM -- outside machines can only send packets to the VM in reply to packets the VM sent to them. On the network, the packets will look like they're coming from/going to the host on some unrelated port.
With bridged networking, the VM gets a device that connects directly to the host's network device. In this mode, the VM appears as a separate machine on the same network LAN as the host, with its own IP address. You need to allocate an IP address for it, the same as the host get allocated an IP address (usually via DHCP).
In either case, to debug what is going on, use tcpdump/wireshark on the host to monitor the host's network device. Send packets from the VM, and you should see them in the trace -- they'll appear to come from the host and a different port in the NAT case, and will appear to come from the VM's IP address (and unchanged ports) in the bridged case.
Once you see that, you should be able to send packets back to the VM, though in the NAT case, they must come FROM the address/port the original packet(s) were sent to.
There are known issues with VirtualBox bridged networking not working properly on wifi devices; in general you can only use bridged networking with wired networks.
Oracles VB manual page clear all the terminology used in settings.
I've had similar problem, where my VB program didn't receive any packets, which I solved by setting "Bridged Networking" and setting up proper source/destination IP address in my program by analyzing WLAN interface with wireshark and using ifconfig (or ipconfig) in terminal.