This chapter has introduced the simplest uses of ifconfig and route to view and alter the IP configuration of a host. To reiterate the minimum requirements to create an IP network between two machines:
Requirements for Two Hosts on the Same Ethernet to Communicate Using IP
Each host must have a good connection to the Ethernet. Verify a good connection to the Ethernet with mii-tool, documented in Section B.5, “mii-tool”.
Each host must share IP network space. Practically, this means that each host should have the same network address, netmask, and broadcast address [8].
Each host must have a unique IP address.
Neither host must block the other's IP packets. (Host based packet filtering may hinder connections!)
This concludes the tour of basic host networking and IP layer configuration as well as some basic tools available to the linux user. For further documentation on these tools, other tips, tricks, and more advanced content, keep reading!
[8] Technically, the two hosts simply need to have routes to each other, but we are discussing the simplest case here, so we'll leave this for a discussion of shared media.