Question Pinging a PC on a remote network?

[vonsworld]

Hi

I'd like to be able to ping a PC on a remote network via the internet.

How do I setup the remote router so that it passes incoming pings to a specific local PC which has a fixed IP address, like 192.168.1.100 and returns the results from that PC to me?

The router has port forwarding but that asks for an incoming and local port address. What should the port address be to forward pings please?

Thanks
Robin

 

[bill001g]

This is where you need to get into the details of what does port forwarding actually mean.

The key thing here is ping uses a "protocol" called ICMP to send data packets. More common traffic use TCP and UDP. These are all different protocol numbers that can exist in ip packets.

The concept of ports really only exists in TCP and UDP.

The router would need some special support to somehow forward ICMP packets. There are similar issue when you try to use IPSEC vpn through nat. Some routers have some limited support for for some of these tunneling protocols.

I have never seen a router that has a method to forward ICMP packets. Maybe some of the third party firmware does.

The solution is to not use ICMP. There are other programs that can simulate ping over TCP or UDP.

You don't really need to use any special program if you are willing to dig around a bit. So if you look at the network tab in the resource monitor under TCP connection you will see a field that show the latency. This is kinda a average number so it is not are detailed as a ping but it does show similar information. You could just run any some application on some random port and you could use this tool.

Now if you directly want to see the timing you can use wireshark. Key here is when a TCP session is first opened you get a series of messages the first 2 can do the same function as ping.

The first sends a SYN packet. The receive replies with a SYN ACK packet. In wireshark you can actually see the timestamps and calculate the difference.

This method works pretty much on any site on the internet that uses TCP...ie web pages. You can just run wireshark and open any site like normal and collect the data. This is a better method when you do not have the option of installing any special software on the remote machine.