You may be interested in implementing your own network testing tools. The ping tool seems pretty simple, and it is. Unfortunately, the socket programming APIs we've been working with do not provide access at the IP level that the ICMP is built on.

The socket programming API does provide access to raw sockets, in theory. With raw sockets, a C program can construct the exact IP packet to send. That is, a C programmer could construct an ICMP packet from scratch and send it over the network. Raw sockets also allow for programs to receive uninterpreted packets from the network directly. In this case, the user program would be responsible for deconstructing and interpreting the ICMP packet, not the operating system.

On systems with raw socket support, getting started can be as simple as changing your socket() function invocation to the following:

socket(AF_INET, SOCK_RAW, IPPROTO_RAW);

However, the problem is that raw sockets aren't universally supported. It is a difficult subject to approach in a cross-platform way. Windows, in particular, has varying support for raw sockets depending on the OS version. Recent versions of Windows have virtually no support for raw sockets. For this reason, we won't cover raw sockets in any more detail here.

Now that we've covered two basic tools for network troubleshooting, let's next look at tools that inform us about our own system's relationship to the network.