ifconfig is used to make an interface accessible to the kernel networking layer. This involves the assignment of an IP-address and other parameters, and activating the interface, also known as ``taking up.'' Being active here means that the kernel will send and receive IP-datagrams through the interface. The simplest way to invoking it is
ifconfig interface ip-addresswhich assigns ip-address to interface and activates it. All other parameters are set to default values. For instance, the default subnet mask is derived from the network class of the IP-address, such as 255.255.0.0 for a class-B address. ifconfig is described in detail at the end of this chapter.
route allows you to add or remove routes from the kernel routing table. It can be invoked as
route [add|del] targetwhere the add and del arguments determine whether to add or delete the route to target.