Red Hat Enterprise 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.
/etc/sysconfig/network-scripts/network-functions 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 the status of an interface, setting host names, finding a gateway device, verifying whether or not a particular device is down, and adding a default route.
As the functions required for
IPv6 interfaces are different from
IPv4 interfaces, a
/etc/sysconfig/network-scripts/network-functions-ipv6 file exists specifically to hold this information. The functions in this file 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.