Sam Stelfox

Thoughts from a software engineer, systems hacker and Linux gubernāre.

Promiscuous Ethernet

Redhat used to to include a way to enable promiscuous mode in the network configuration scripts. This was deprecated and no longer available but can be restored by creating / adding to the /sbin/ifup-local file:

#!/bin/bash

RC=0

PROM=$(egrep -i 'promisc' /etc/sysconfig/network-scripts/ifcfg-$1 | awk -F"=" '{ print $2 }')

if [ "$PROM" = "yes" ]; then
  /usr/sbin/ip link set dev $1 promisc on
  #/sbin/ifconfig $1 promisc
  RC=$?
fi

exit $RC

You can then use this in /etc/sysconfig/network-scripts/ifcfg-eth0 like files by adding "PROMISC=yes" somewhere in it. This is untested.