Linux Run Process without Networking

run_without_internet.bash

#!/bin/bash
# IPTABLES Matching by PID got removed in 2005.

# Usage: foo.bash 0 ping -c 4 -w 1 1.1.1
#        foo.bash 1 ping -c 4 -w 1.1.1.1

IPTABLES="/sbin/iptables"
REJECT_MODE="DROP" # REJECT, DROP
RANDOM_FUNC=$(( ( RANDOM % 30000 ) + 10000 ))

TEMP_ARGS=("$@")
VERBOSE=${TEMP_ARGS[0]}
unset 'TEMP_ARGS[0]'
RUN_COMMAND="${TEMP_ARGS[@]}"

USERADD="/usr/sbin/useradd"
USERMOD="/usr/sbin/usermod"
USERDEL="/usr/sbin/userdel"

# Get Last PID (for Randomly Generate User)
[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Create Random Username"
`echo 1 > /dev/null` &
LAST_PID=$!
GET_RANDOM=`echo $RANDOM_FUNC`
RANDOM_DIGEST="temp-${LAST_PID}-${GET_RANDOM}"
NEW_UID=$GET_RANDOM

[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] -- USERNAME : $RANDOM_DIGEST, UID=$NEW_UID"

[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Create Temporary User for process [UID=$NEW_UID]"
$USERADD -M $RANDOM_DIGEST -u $NEW_UID
$USERMOD -L $RANDOM_DIGEST

[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Blocking Networking..."
$IPTABLES -I OUTPUT -m owner --uid-owner $NEW_UID -j $REJECT_MODE

[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Run process"

su $RANDOM_DIGEST -c "$RUN_COMMAND" &
NEW_PID=$!

#while [ -n "$NEW_PID" -a -e /proc/$NEW_PID ];
#do
#    [[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Process [$NEW_PID] is running."
#    sleep 1
#done

wait $NEW_PID
RETURN_CODE=$?

[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Unblocking Networking..."
$IPTABLES -D OUTPUT -m owner --uid-owner $NEW_UID -j $REJECT_MODE

[[ "$VERBOSE" -gt "0" ]] && echo "[BASH] Remove Temporary User"
$USERDEL $RANDOM_DIGEST

exit $RETURN_CODE

useless