Handbook:X86/Networking/Extending

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X86 Handbook
Installation
About the installation
Choosing the media
Configuring the network
Preparing the disks
Installing stage3
Installing base system
Configuring the kernel
Configuring the system
Installing tools
Configuring the bootloader
Finalizing
Working with Gentoo
Portage introduction
USE flags
Portage features
Initscript system
Environment variables
Working with Portage
Files and directories
Variables
Mixing software branches
Additional tools
Custom package repository
Advanced features
Network configuration
Getting started
Advanced configuration
Modular networking
Wireless
Adding functionality
Dynamic management


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 de-configuration 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 de-configuration.

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.

FILE /etc/conf.d/netpre/post up/down function examples
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 functions, please read /usr/share/doc/netifrc-*/net.example.bz2.

Wireless tools function hook

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 de-configuration 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 the system is connecting to. ${ESSIDVAR} is ${ESSID} converted to a variable name bash allows.

FILE /etc/conf.d/netpre/post association functions
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 custom functions, please read /usr/share/doc/netifrc-*/net.example.bz2.