The interface control scripts control bringing up (activating) and down
(deactivating) interface connections. There are two primary interface
control scripts, /sbin/ifdown and
/sbin/ifup, that use assorted other control scripts
located in the /etc/sysconfig/network-scripts
directory to actually bring the network interfaces up and down.
The two primary interface control scripts in the
/etc/sysconfig/network-scripts directory,
ifdown and ifup, are symbolic
links to the scripts in the /sbin
directory. When either of these scripts are called, they accept a
value of the interface to be used, such as:
[root@bleach network-scripts]# ifup eth0
Determining IP information for eth0... done.
[root@bleach network-scripts]# |
At that point, the
/etc/sysconfig/network-scripts/network-functions
and /etc/rc.d/init.d/functions files are sourced
and functions from those files are used to perform a variety of tasks. See
the section called Network Functions for more information about
these tasks.
After verifying that an interface has been specified and that the user
executing the request is allowed to bring the interface up or down, the
correct script for the type of interface device is called into
action. This is the script that actually brings the interface up and
down. The following interface control scripts are the most common of
this type:
ifup-aliases — Configures IP aliases from
interface configuration files when more than one IP address is
associated with an interface.
ifdown-cipcb and
ifup-cipcb — Used to bring
Crypto IP Encapsulation (CIPE) connections up
and down.
ifdown-ipv6 and
ifup-ipv6 — Contains IPv6-related
function calls that utilize the environment variables in various
interface configuration files and
/etc/sysconfig/network.
ifup-ipx — Used to bring up an IPX interface.
ifup-plip — Used to bring up a PLIP interface.
ifup-plusb — Used to bring up a USB
interface for network connections.
ifdown-post and ifup-post
— Contains commands to be executed after a particular
interface is brought up or down, such as configuring IP aliases or
routes by calling certain scripts, such as
ifup-aliases or
ifup-routes.
ifdown-ppp and ifup-ppp
— Used to bring a PPP interface up or down using a particular
device.
ifup-routes — Adds static routes for a
particular device as its interface is brought up.
ifdown-sit and ifup-sit
— Contains function calls related to bringing up and down an
IPv6 tunnel within an IPv4 connection.
ifdown-sl and
ifup-sl — Used to bring an SLIP interface
up or down.
In order to bring a particular interface up or down properly, these
scripts may call one another to provide a certain type of
functionality. In addition, other scripts will find their way into the
/etc/sysconfig/network-scripts directory as
software is installed that requires a new type of interface. Be aware
that removing or modifying these scripts can cause various interface
connections to act strangely or fail, as these scripts tend to rely on
each other. However, advanced users can modify scripts linked with a
specific interface to make additional steps occur when that interface is
brought up or down.
You can also use the init script
/etc/rc.d/init.d/network to activate and deactive
all network interfaces configured to start at boot time with the
command:
/sbin/service network action |
where action is either
start to start the network interfaces,
stop to stop the network interfaces, or
restart to restart the network interfaces.
You can also use the command /sbin/service/network
status to view a list of configured devices and currently
active devices.
Instructions for making interfaces active and inactive, through the use
of the command line or GUI-based administration tools, can be found in
the Official Red Hat Linux Customization Guide.
