Two clients in the same nat cannot communicate with each other

[xmh0511]

     Server
       |
       NAT 
     /     \
    /       \
  A           B 

In this network structure, A and B may have the same public IP and different ports, and A cannot successfully send packets to B nor vice versa since the NAT does not support NAT_hairpinning. We may need to make A directly send packets to B via the local network IP addresses?

[M0dEx]

This technically should not be needed, as the traffic will be routed through the server. Since the clients only share the IP, not the socket, the traffic should pass just fine.

However, routing traffic between clients does not work as of now, which seems to be a bug in the server-side implementation: #41.

[M0dEx]

@xmh0511 Could you test this with the client-isolation branch?

cargo install quincy --git https://github.com/M0dEx/quincy.git --branch 'client-isolation'

When you set isolate_clients in the server config to false, you should be able to send traffic between the two clients through the Quincy connection.

[xmh0511]

@xmh0511 Could you test this with the client-isolation branch?

cargo install quincy --git https://github.com/M0dEx/quincy.git --branch 'client-isolation'

When you set isolate_clients in the server config to false, you should be able to send traffic between the two clients through the Quincy connection.

Running two clients, one is on my macOS, and another is on Windows in my vmware. The windows client can successfully ping the one on macOS, but not vice versa.

windows

macOS

[M0dEx]

What does the routing table look like on Windows and on MacOS?

Windows: route print -4 MacOS: netstat -nr -f inet

[xmh0511]

What does the routing table look like on Windows and on MacOS?

Windows: route print -4 MacOS: netstat -nr -f inet

windows

macOS

Windows ping macOS -> Successfully

ping 10.0.2.3

macOS ping Windows -> fail

ping 10.0.2.2

[M0dEx]

Fortunately, I have the acces to a Windows and a MacOS system, so I will attempt to reproduce this locally and come up with a fix.

[M0dEx]

Seems this is not an issue with Quincy. Inbound ICMP is dropped by default on Windows. You have to enable the Core Networking Diagnostics - ICMP Echo Request (ICMPv4-In) rule for the ping from MacOS to work.

[xmh0511]

Seems this is not an issue with Quincy. Inbound ICMP is dropped by default on Windows. You have to enable the Core Networking Diagnostics - ICMP Echo Request (ICMPv4-In) rule for the ping from MacOS to work.

That's the actual reason here. I ran the command

netsh firewall set icmpsetting 8

on my Windows, and it works now. Seems this issue has been fixed.