| At this point, we have one system that is able to send out data onto the external network. The remaining machines only have routes to the internal network defined on them, which means that while they can talk to each other quite happily, they don't know how to send out data onto the Internet. To allow them to do this, we'll create a default route on each system as before, but this time it will point to xenon. We will also need to update their nsswitch.conf as we did previously to use DNS for hosts lookup. Once this is complete, if any systems need to send or receive data from a machine they don't know about, they will pass it to xenon, which in turn will send it externally (see Figure 13.2). Figure 13.2. External packet flow using the default route. 
Since we are using DNS, we'll also need to create a resolv.conf as before. The entries will be the same for the clients as they were for xenon, so we'll simply copy the entries over. On these systems, the defaultrouter file will look like the one shown below: hydrogen# cat /etc/defaultrouter 192.168.44.54 hydrogen# As before, we have used IP addresses rather than host names to try and lighten any administration tasks. We also need to reboot the systems for the defaultrouter file to be used. After that, we can check that we can see an external system exactly as we did with xenon: hydrogen# ping www.sun.com www.sun.com is alive hydrogen# | 
