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.TH ifup 8 "22 May 2004" IFUPDOWN ""
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ifup \- bring a network interface up
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ifdown \- take a network interface down
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[\fB\-i\fR \fIFILE\fR|\fB\-\-interfaces=\fR\fIFILE\fR]
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[\fB\-\-allow\fR \fICLASS\fR]
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\fB\-a\fR|\fIIFACE\fR...
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\fB\-h\fR|\fB\-\-help\fR
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\fB\-V\fR|\fB\-\-version\fR
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[\fB\-i\fR \fIFILE\fR|\fB\-\-interfaces=\fR\fIFILE\fR]
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[\fB\-\-allow\fR \fICLASS\fR]
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\fB\-a\fR|\fIIFACE\fR...
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.BR ifup " and " ifdown
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commands may be used to configure (or, respectively, deconfigure) network
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interfaces based on interface definitions in the file
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.IR /etc/network/interfaces .
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A summary of options is included below.
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If given to \fBifup\fP, affect all interfaces marked \fBauto\fP.
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Interfaces are brought up in the order in which they are defined
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in /etc/network/interfaces.
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If given to \fBifdown\fP, affect all defined interfaces.
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Interfaces are brought down in the order in which they are
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currently listed in the state file. Only interfaces defined
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in /etc/network/interfaces will be brought down.
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Force configuration or deconfiguration of the interface.
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Show summary of options.
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\fB\-\-allow=\fR\fICLASS\fR
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Only allow interfaces listed in an
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line in /etc/network/interfaces to be acted upon.
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\fB\-i\fR \fIFILE\fR, \fB\-\-interfaces=\fR\fIFILE\fR
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Read interface definitions from
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instead of from /etc/network/interfaces.
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.BR \-n ", " \-\-no\-act
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Don't configure any interfaces or run any "up" or "down" commands.
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Don't run any mappings. See
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for more information about the mapping feature.
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.BR \-V ", " \-\-version
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Show copyright and version information.
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.BR \-v ", " \-\-verbose
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Show commands as they are executed.
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Bring up all the interfaces defined with
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.I /etc/network/interfaces
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Bring down all interfaces that are currently up.
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.BR ifup " and " ifdown
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are actually the same program called by different names.
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The program does not configure network interfaces directly;
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it runs low level utilities such as
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.BR ifconfig " and " route
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to do its dirty work.
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.I /etc/network/interfaces
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definitions of network interfaces
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for more information.
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.I /etc/network/run/ifstate
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current state of network interfaces
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.SH KNOWN BUGS/LIMITATIONS
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The program keeps records of whether network interfaces are up or down.
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Under exceptional circumstances these records can become
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inconsistent with the real states of the interfaces.
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For example, an interface that was brought up using
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and later deconfigured using
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will still be recorded as up.
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To fix this you can use the
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to run configuration or deconfiguration commands despite what
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it considers the current state of the interface to be.
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.I /etc/network/run/ifstate
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If that location is not writable
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(for example, because the root filesystem is mounted read-only
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.I /etc/network/run/ifstate
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should be made a symbolic link to a writable location.
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If that is not possible then you can use the
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option to run configuration or deconfiguration commands
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without updating the file.
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Note that the program does not run automatically:
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alone does not bring up interfaces
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that appear as a result of hardware being installed and
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alone does not bring down interfaces
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that disappear as a result of hardware being removed.
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To automate the configuration of network interfaces you need to
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install other packages such as
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The ifupdown suite was written by Anthony Towns <aj@azure.humbug.org.au>.