Gentoo Logo

Disclaimer : This handbook has been replaced by a newer version and is not maintained anymore.


[ << ] [ < ] [ Home ] [ > ] [ >> ]


5. Adding Functionality

Content:

5.a. Standard function hooks

Four functions can be defined in /etc/conf.d/net which will be called surrounding the start/stop operations. The functions are called with the interface name first so that one function can control multiple adapters.

The return values for the preup() and predown() functions should be 0 (success) to indicate that configuration or deconfiguration of the interface can continue. If preup() returns a non-zero value, then interface configuration will be aborted. If predown() returns a non-zero value, then the interface will not be allowed to continue deconfiguration.

The return values for the postup() and postdown() functions are ignored since there's nothing to do if they indicate failure.

${IFACE} is set to the interface being brought up/down. ${IFVAR} is ${IFACE} converted to variable name bash allows.

Code ListingĀ 1.1: pre/post up/down function examples in /etc/conf.d/net

preup() {
  # Test for link on the interface prior to bringing it up.  This
  # only works on some network adapters and requires the ethtool
  # package to be installed.
  if ethtool ${IFACE} | grep -q 'Link detected: no'; then
    ewarn "No link on ${IFACE}, aborting configuration"
    return 1
  fi

  # Remember to return 0 on success
  return 0
}

predown() {
  # The default in the script is to test for NFS root and disallow
  # downing interfaces in that case.  Note that if you specify a
  # predown() function you will override that logic.  Here it is, in
  # case you still want it...
  if is_net_fs /; then
    eerror "root filesystem is network mounted -- can't stop ${IFACE}"
    return 1
  fi

  # Remember to return 0 on success
  return 0
}

postup() {
  # This function could be used, for example, to register with a
  # dynamic DNS service.  Another possibility would be to
  # send/receive mail once the interface is brought up.
       return 0
}

postdown() {
  # This function is mostly here for completeness... I haven't
  # thought of anything nifty to do with it yet ;-)
  return 0
}

Note: For more information on writing your own functions, please read /usr/share/doc/netifrc-*/net.example.bz2.

5.b. Wireless Tools function hooks

Note: This will not work with WPA Supplicant - but the ${ESSID} and ${ESSIDVAR} variables are available in the postup() function.

Two functions can be defined in /etc/conf.d/net which will be called surrounding the associate function. The functions are called with the interface name first so that one function can control multiple adapters.

The return values for the preassociate() function should be 0 (success) to indicate that configuration or deconfiguration of the interface can continue. If preassociate() returns a non-zero value, then interface configuration will be aborted.

The return value for the postassociate() function is ignored since there's nothing to do if it indicates failure.

${ESSID} is set to the exact ESSID of the AP you're connecting to. ${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.

Code ListingĀ 2.1: pre/post association functions in /etc/conf.d/net

preassociate() {
  # The below adds two configuration variables leap_user_ESSID
  # and leap_pass_ESSID. When they are both configured for the ESSID
  # being connected to then we run the CISCO LEAP script

  local user pass
  eval user=\"\$\{leap_user_${ESSIDVAR}\}\"
  eval pass=\"\$\{leap_pass_${ESSIDVAR}\}\"

  if [[ -n ${user} && -n ${pass} ]]; then
    if [[ ! -x /opt/cisco/bin/leapscript ]]; then
      eend "For LEAP support, please emerge net-misc/cisco-aironet-client-utils"
      return 1
    fi
    einfo "Waiting for LEAP Authentication on \"${ESSID//\\\\//}\""
    if /opt/cisco/bin/leapscript ${user} ${pass} | grep -q 'Login incorrect'; then
      ewarn "Login Failed for ${user}"
      return 1
    fi
  fi

  return 0
}

postassociate() {
  # This function is mostly here for completeness... I haven't
  # thought of anything nifty to do with it yet ;-)

  return 0
}

Note: ${ESSID} and ${ESSIDVAR} are unavailable in predown() and postdown() functions.

Note: For more information on writing your own functions, please read /usr/share/doc/netifrc-*/net.example.bz2.


[ << ] [ < ] [ Home ] [ > ] [ >> ]


Print

View all

Page updated December 17, 2013

Summary: If you're feeling adventurous, you can add your own functions to networking.

Sven Vermeulen
Author

Roy Marples
Author

Daniel Robbins
Author

Chris Houser
Author

Jerry Alexandratos
Author

Seemant Kulleen
Gentoo x86 Developer

Tavis Ormandy
Gentoo Alpha Developer

Jason Huebel
Gentoo AMD64 Developer

Guy Martin
Gentoo HPPA developer

Pieter Van den Abeele
Gentoo PPC developer

Joe Kallar
Gentoo SPARC developer

John P. Davis
Editor

Pierre-Henri Jondot
Editor

Eric Stockbridge
Editor

Rajiv Manglani
Editor

Jungmin Seo
Editor

Stoyan Zhekov
Editor

Jared Hudson
Editor

Colin Morey
Editor

Jorge Paulo
Editor

Carl Anderson
Editor

Jon Portnoy
Editor

Zack Gilburd
Editor

Jack Morgan
Editor

Benny Chuang
Editor

Erwin
Editor

Joshua Kinard
Editor

Xavier Neys
Editor

Grant Goodyear
Reviewer

Gerald J. Normandin Jr.
Reviewer

Donnie Berkholz
Reviewer

Ken Nowack
Reviewer

Lars Weiler
Contributor

Tobias Scherbaum
Editor

Donate to support our development efforts.

Copyright 2001-2014 Gentoo Foundation, Inc. Questions, Comments? Contact us.