# Function that returns a random network interface out of a bunch of
# alias interfaces, per example, eth0:23 or ens9:2. This effectively
# helps in using a different ip/interface for whatever needs...
# Excludes local interface lo and because i use it, loc0
# Part of or a full interface name can be excluded by calling the
# function with a parameter. Like so: random-interface eth0
#
# Example (would return your ip)
#
# curl -A "cURL/randif.test" -sLk --interface $(random-interface) https://v4.4ce.ca
# # To return from all interfaces, except local and all eth0*
# curl -A "cURL/randif.test" -sLk --interface $(random-interface eth0) https://v4.4ce.ca
# # To return from all interfaces, except local ONLY 'eth0'
# curl -A "cURL/randif.test" -sLk --interface $(random-interface ^eth0$) https://v4.4ce.ca
#
function random-interface() {
local RANDIF IFEX;
# If part of or a interface name is specified on the command-line,
# then exclude it from the list of returned interfaces.
[[ ! -z ${1} ]] && IFEX="${1}" || IFEX="^$";
# Get all interfaces list then process it and add found interfaces to RANDIF variable, except for input
for I in $(ifconfig | cut -d' ' -f1 | sed 's/: /\n/g' | awk NF | sed 's/:$//g' | grep -Ev "lo|loc0|loopback|00:00:00:00:00:00|${IFEX}"); do
RANDIF+=("${I}");
done
if [[ -z ${RANDIF} ]]; then
>&2 echo -e "\\033[1;38;5;160mERROR\\033[0;1m:\\033[0m No interfaces available.";
else
echo ${RANDIF[$(( ${RANDOM} % ${#RANDIF[@]} ))]};
fi
}
alias randif='random-interface';
