Unable to reach the IP on the same subnet (EmuFdNetDevice)

[Muhammad Nauman Chattha]

Hello,

I am trying to understand the EmuFdNetDevice but cannot ping an IP in the same subnet.

I am working with the fd-emu-ping example. I gave the emudevice IP (192.168.1.50) .

First I tried to ping 8.8.8.8 and my gateway IP (192.168.1.1) both worked. 

When I give my laptop's IP(192.168.1.100) enp0s25 it's unable to ping it. 

I checked my routing table and it seems fine to me:

I tried debugging with tcpdump and it seems like its unable to resolve the ARP request,

can you please guide what can be wrong here? any hints?

Regards

Nauman

 

[Devanshu Anand]

Hi Nauman,

When you are running tcpdump, try to store it in a form of pcap file. 

You can use a command like this in your terminal. "sudo tcpdump --interface any -n udp port 2222 -s 123456 -w /tmp/tcpdump.pcap". The port number and interface will change according to your settings. Once this is done, you can download the pcap from the folder (in this case, it is /tmp). pcap file will be an easy way to determine the issue and find the solution.

Thanks,

Devanshu

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Thanks & Regards,
Devanshu Anand

Doctoral Researcher,
Dublin City University | School of Electronic Engineering
Glasnevin, Dublin 9
Ireland

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[Muhammad Nauman Chattha]

Hi Devanshu,

I am unable to use the above command that you gave as it gives the error "tcpdump: Couldn't change ownership of savefile" . Although using the ns3 pcap option, I have the pcap files for both cases.

Here screenshot of pcap file for the working case :

in this, it seems like it asked for the gateway, and from there everything is sorted.

Now the second case is for the subnet IP on the same machine.(192.168.1.100). it sends an ARP but receives no response

What can be the reason for not getting back a response? Can you help me understand the issue here?

regards

Chattha

[Muhammad Nauman Chattha]

I able to resolve this issue with a VM. it seems like it can't ping an IP on the same interface e.g: I was using the eth0 and the machine IP was also on the same interface.