C.2 Standard Internet Services

Be familiar with the standard Internet services described in Figure 2.18. We have used the daytime service many times for testing our clients. The discard service is a convenient port to which we can send data. The echo service is similar to the echo server we have used throughout this text.

Many sites now prevent access to these services through their firewalls because of some denial-of-service attacks using these services in 1996 (Exercise 13.3). Nevertheless, you can hopefully use these services within your own network.