8.4. Network Function Files
Red Hat Linux makes use of several files that contain important common functions
used to bring interfaces up and down. Rather than forcing each interface
control file to contain these functions, they are grouped together in a
few files that are called upon when necessary.
file contains the most commonly used IPv4 functions, which are useful to
many interface control scripts. These functions include contacting
running programs that have requested information about changes in an
interface's status, setting hostnames, finding a gateway device, seeing
if a particular device is down, and adding a default route.
As the functions required for IPv6 interfaces are different than IPv4
interfaces, a network-functions-ipv6 file exists
specifically to hold this information. IPv6 support must be enabled in
the kernel in order to communicate via that protocol. A function is
present in the network-functions file that checks
for the presence of IPv6 support. Additionally, functions that configure
and delete static IPv6 routes, create and remove tunnels, add and remove
IPv6 addresses to an interface, and test for the existence of an IPv6
address on an interface can be found in this file.