#!/bin/bash # iptables-apply -- a safer way to update iptables remotely # # Usage: # iptables-apply [-hV] [-t timeout] [-w savefile] {[rulesfile]|-c [runcmd]} # # Versions: # * 1.0 Copyright 2006 Martin F. Krafft <madduck@madduck.net> # Original version # * 1.1 Copyright 2010 GW <gw.2010@tnode.com or http://gw.tnode.com/> # Added parameter -c (run command) # Added parameter -w (save successfully applied rules to file) # Major code cleanup # # Released under the terms of the Artistic Licence 2.0 # set -eu PROGNAME="${0##*/}" VERSION=1.1 ### Default settings DEF_TIMEOUT=10 MODE=0 # apply rulesfile mode # MODE=1 # run command mode case "$PROGNAME" in (*6*) SAVE=ip6tables-save RESTORE=ip6tables-restore DEF_RULESFILE="/etc/network/ip6tables.up.rules" DEF_SAVEFILE="$DEF_RULESFILE" DEF_RUNCMD="/etc/network/ip6tables.up.run" ;; (*) SAVE=iptables-save RESTORE=iptables-restore DEF_RULESFILE="/etc/network/iptables.up.rules" DEF_SAVEFILE="$DEF_RULESFILE" DEF_RUNCMD="/etc/network/iptables.up.run" ;; esac ### Functions function blurb() { cat <<-__EOF__ $PROGNAME $VERSION -- a safer way to update iptables remotely __EOF__ } function copyright() { cat <<-__EOF__ $PROGNAME has been published under the terms of the Artistic Licence 2.0. Original version - Copyright 2006 Martin F. Krafft <madduck@madduck.net>. Version 1.1 - Copyright 2010 GW <gw.2010@tnode.com or http://gw.tnode.com/>. __EOF__ } function about() { blurb echo copyright } function usage() { blurb echo cat <<-__EOF__ Usage: $PROGNAME [-hV] [-t timeout] [-w savefile] {[rulesfile]|-c [runcmd]} The script will try to apply a new rulesfile (as output by iptables-save, read by iptables-restore) or run a command to configure iptables and then prompt the user whether the changes are okay. If the new iptables rules cut the existing connection, the user will not be able to answer affirmatively. In this case, the script rolls back to the previous working iptables rules after the timeout expires. Successfully applied rules can also be written to savefile and later used to roll back to this state. This can be used to implement a store last good configuration mechanism when experimenting with an iptables setup script: $PROGNAME -w $DEF_SAVEFILE -c $DEF_RUNCMD When called as ip6tables-apply, the script will use ip6tables-save/-restore and IPv6 default values instead. Default value for rulesfile is '$DEF_RULESFILE'. Options: -t seconds, --timeout seconds Specify the timeout in seconds (default: $DEF_TIMEOUT). -w savefile, --write savefile Specify the savefile where successfully applied rules will be written to (default if empty string is given: $DEF_SAVEFILE). -c runcmd, --command runcmd Run command runcmd to configure iptables instead of applying a rulesfile (default: $DEF_RUNCMD). -h, --help Display this help text. -V, --version Display version information. __EOF__ } function checkcommands() { for cmd in "${COMMANDS[@]}"; do if ! command -v "$cmd" >/dev/null; then echo "Error: needed command not found: $cmd" >&2 exit 127 fi done } function revertrules() { echo -n "Reverting to old iptables rules... " "$RESTORE" <"$TMPFILE" echo "done." } ### Parsing and checking parameters TIMEOUT="$DEF_TIMEOUT" SAVEFILE="" SHORTOPTS="t:w:chV"; LONGOPTS="timeout:,write:,command,help,version"; OPTS=$(getopt -s bash -o "$SHORTOPTS" -l "$LONGOPTS" -n "$PROGNAME" -- "$@") || exit $? for opt in $OPTS; do case "$opt" in (-*) unset OPT_STATE ;; (*) case "${OPT_STATE:-}" in (SET_TIMEOUT) eval TIMEOUT="$opt";; (SET_SAVEFILE) eval SAVEFILE="$opt" [ -z "$SAVEFILE" ] && SAVEFILE="$DEF_SAVEFILE" ;; esac ;; esac case "$opt" in (-t|--timeout) OPT_STATE="SET_TIMEOUT";; (-w|--write) OPT_STATE="SET_SAVEFILE";; (-c|--command) MODE=1;; (-h|--help) usage >&2; exit 0;; (-V|--version) about >&2; exit 0;; (--) break;; esac shift done # Validate parameters if [ "$TIMEOUT" -ge 0 ] 2>/dev/null; then TIMEOUT=$((TIMEOUT)) else echo "Error: timeout must be a positive number" >&2 exit 1 fi if [ -n "$SAVEFILE" ] && [ -e "$SAVEFILE" ] && [ ! -w "$SAVEFILE" ]; then echo "Error: savefile not writable: $SAVEFILE" >&2 exit 8 fi case "$MODE" in (1) # Treat parameter as runcmd (run command mode) RUNCMD="${1:-$DEF_RUNCMD}" if [ ! -x "$RUNCMD" ]; then echo "Error: runcmd not executable: $RUNCMD" >&2 exit 6 fi # Needed commands COMMANDS=(mktemp "$SAVE" "$RESTORE" "$RUNCMD") checkcommands ;; (*) # Treat parameter as rulesfile (apply rulesfile mode) RULESFILE="${1:-$DEF_RULESFILE}"; if [ ! -r "$RULESFILE" ]; then echo "Error: rulesfile not readable: $RULESFILE" >&2 exit 2 fi # Needed commands COMMANDS=(mktemp "$SAVE" "$RESTORE") checkcommands ;; esac ### Begin work # Store old iptables rules to temporary file TMPFILE=$(mktemp "/tmp/$PROGNAME-XXXXXXXX") trap 'rm -f $TMPFILE' EXIT HUP INT QUIT ILL TRAP ABRT BUS \ FPE USR1 SEGV USR2 PIPE ALRM TERM if ! "$SAVE" >"$TMPFILE"; then # An error occured if ! grep -q ipt /proc/modules 2>/dev/null; then echo "Error: iptables support lacking from the kernel" >&2 exit 3 else echo "Error: unknown error saving old iptables rules: $TMPFILE" >&2 exit 4 fi fi # Legacy to stop the fail2ban daemon if present [ -x /etc/init.d/fail2ban ] && /etc/init.d/fail2ban stop # Configure iptables case "$MODE" in (1) # Run command in background and kill it if it times out echo -n "Running command '$RUNCMD'... " "$RUNCMD" & CMD_PID=$! ( sleep "$TIMEOUT"; kill "$CMD_PID" 2>/dev/null; exit 0 ) & if ! wait "$CMD_PID"; then echo "failed." echo "Error: unknown error running command: $RUNCMD" >&2 revertrules exit 7 else echo "done." fi ;; (*) # Apply iptables rulesfile echo -n "Applying new iptables rules from '$RULESFILE'... " if ! "$RESTORE" <"$RULESFILE"; then echo "failed." echo "Error: unknown error applying new iptables rules: $RULESFILE" >&2 revertrules exit 5 else echo "done." fi ;; esac # Prompt user for confirmation echo -n "Can you establish NEW connections to the machine? (y/N) " read -r -n1 -t "$TIMEOUT" ret 2>&1 || : case "${ret:-}" in (y*|Y*) # Success echo if [ -n "$SAVEFILE" ]; then # Write successfully applied rules to the savefile echo "Writing successfully applied rules to '$SAVEFILE'..." if ! "$SAVE" >"$SAVEFILE"; then echo "Error: unknown error writing successfully applied rules: $SAVEFILE" >&2 exit 9 fi fi echo "... then my job is done. See you next time." ;; (*) # Failed echo if [ -z "${ret:-}" ]; then echo "Timeout! Something happened (or did not). Better play it safe..." else echo "No affirmative response! Better play it safe..." fi revertrules exit 255 ;; esac # Legacy to start the fail2ban daemon again [ -x /etc/init.d/fail2ban ] && /etc/init.d/fail2ban start exit 0 # vim:noet:sw=8