Re: macchanger - is it still working?

[Stefan Krusche <linux@stefan-krusche.de>]

Good Day Everyone,

Am Montag, 9. Mai 2022 schrieb Hans:
> IFACE = --all
> /usr/bin/macchanger: unrecognized option '--all'
> GNU MAC Changer

Yes. The problem is that the script /etc/macchanger/ifupdown.sh which is 
shipped with the macchanger package processes $IFACE without checking 
its value.

package=macchanger
/usr/bin/${package} -e $IFACE >> $LOGFILE 2>&1

When $IFACE == "--all" which is a valid option for ifup as David pointed 
out then macchanger fails and reports the above error message to its 
logfile because macchanger understands "--all" as on option which it 
doesn't know.

Am Montag, 9. Mai 2022 schrieb David Wright:
> A workaround for your problem might be to set IFACE appropriately
> in /etc/default/macchanger.

A solution I found is to change the script /etc/macchanger/ifupdown.sh 
so that it checks for the value of $IFACE against the value of 
$ENABLE_INTERFACES (sourced from /etc/default/macchanger) and only then 
processes that accordingly. $ENABLE_INTERFACES on my system contains 
only "net0" so all is fine here.

A version of this script which works on my system (Devuan Beowulf) is 
attached.

Another approach I haven't tested yet could be to add "--" to the line 
which invokes maccanger so that the value of "$IFACE" being "--all" 
wouldn't be treated as an option but as an argument and given to ifup 
or whatever macchanger internally uses to actually change the MAC. But 
I don't know if macchanger understands "--".

/usr/bin/$package -a -- "$IFACE" >> $LOGFILE 2>&1

HTH

Kind regards,
Stefan

#!/bin/sh
# $Id: ifupdown.sh,v 2.0 2021-04-21 16:23:42+02 stekru Exp $
# randomize MAC address before connecting to wifi or ethernet
#
# This script should always be run in if-pre-up.d, but unfortunately
# NetworkManager does not run if-pre-up.d scripts before it sets up a network
# connection (https://bugzilla.gnome.org/show_bug.cgi?id=387832).
# if-post-down.d scripts are run, so there is a symlink to this script
# there. That means when running network config from the terminal, macchanger
# will be run twice, but it'll only be run in if-post-down.d when using
# NetworkManager.

package=macchanger
LOGFILE=/var/log/$package.log
#LOGFILE=~/.local/log/$package.log

echo >> $LOGFILE
date '+%Y-%m-%d %T'  >> $LOGFILE

# Vorgaben einlesen; hier wird auch ENABLE_INTERFACES="net0" eingelesen.
if [ -f /etc/default/$package ]; then
    . /etc/default/$package
else
    echo "Config file /etc/default/$package not found" >> $LOGFILE
    exit 1
fi

if [ "$ENABLE_ON_POST_UP_DOWN" != "true" ]; then
    echo "Macchanger is disabled in /etc/default/$package" >> $LOGFILE
    exit
fi

# Where comes '$IFACE' from? From networking or ifup/-down/-query?
# The variable could be read from the environment. Where (from which
# program) would it be exported. No arguemnts are being processed here.
echo "Processing: IFACE = $IFACE" >> $LOGFILE

if [ -z "$ENABLE_INTERFACES" ]; then
    echo "No interface enabled in /etc/default/$package" >> $LOGFILE
    exit 0
else
    case "$IFACE" in
        *$ENABLE_INTERFACES*)
            /usr/bin/$package -a "$IFACE" >> $LOGFILE 2>&1
        ;;
        *)
            echo "Ignoring not configured interface: $IFACE" >> $LOGFILE
            exit 0
        ;;
    esac
fi