Testing and Using your Connection

There are two ways of testing your TCP/IP connection.

The first test tests for another machine's presence on the IP network. This test uses the PING utility.

The second test tests whether you can use an application layer protocol to communcate with the remote machine.

Using PING

The Packet InterNet Groper (PING) test shows whether a remote host is available on the network.

It works by sending an ICMP echo request packet to the specified IP address. If the selected machine is operating, it will receive the ICMP echo request, and return an ICMP echo response packet to the originating host. For each successful ICMP echo request and response pair, the orginating host will print a message indicating a successful ping.

To perform the PING test issue the following command :

ping <IP Address>

Alternatively, you can specify the host name instead of the IP address as long as you have made a corresponding entry in /etc/hosts.

Telnetting

Now that you have tested that the IP host is visable on the network using the PING test, you can now test your configuration using the application protocol TELNET.

The TELNET protocol is a virtual terminal protocol. It sets up a connection to the remote machine and pretends to be a dumb terminal.

It is a good test because it shows that the other machine is communcating, and also supporting one of the most common application services available.

To initiate a Telnet connection to the remote machine, issue the following command :

telnet <hostname>

Alternatively, you could use the IP address instead of the hostname.

After a short period, you should be presented with a banner showing the name of the remote machine, and a login prompt. At this login prompt, you can enter a user name of one of the users of the remote host. You then enter the password, and if it is correct, you will be logged in at a command line prompt, where you can issue any shell commands.

At this point, you have a fully networked Linux box. Any other services the remote machine is running, such as an FTP server or a Web server can now be accessed over the network.