Android Vpnservice to Capture Packets Won't Capture Packets

Android VpnService to capture packets won't capture packets

Ok, it was not easy at all but I figured out how to capture packets. Since I am not extremely familiar with networking (but this new job is requesting that I am) I had difficulty with setting everything correctly. Basically after setting the right route in the VpnService.builder I got to receiving packets correctly.

So:

builder.addAddress("192.168.0.6", 24); // was wrong, you need to put an internal IP (10.0.2.0 for example)

and

builder.addRoute("0.0.0.0", 0); // needs to be this.

you don't need to set up a DnsServer through builder.addDnsServer() to make it work. Hope this helps anyone!

A firewall for Android with VpnService. Responses are delivered, but a SocketTimeoutException is thrown

The point was that I used a wrong IPv4 pseudo header to compute the checksum. It contained neither the packet UDP header nor the transmitted data. Since I included the UDP header and the data, I haven't seen the exception from the original question.

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