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-   -   yes sir, another iptables management script! (http://www.linuxquestions.org/questions/linux-security-4/yes-sir-another-iptables-management-script-911936/)

Juako 11-04-2011 06:56 PM

yes sir, another iptables management script!
 
3 Attachment(s)
Yes I know there must be hundreds of these here at LQ, and most folks already did their own (and probably don't want to look at it again) YES i know there's ufw, gufw, Shorewall, and a thousand other frontends for iptables.

So here's mine :). I love it. I've been using it from years, tuning it up a bit from time to time when my bash improves.

I know iptables syntax by heart, but this script saves me hours when I'm tweaking something and also I use it from my rc scripts to manage my firewall.

Name it as you want, perhaps "yyais" (yes, yet another iptables script) would be a good name.

It's based on "profiles" which are simple iptables-save format files, which means you can try it right away with your current config if you want: if you want to play, make a backup of your current config with:

root@localhost:/# yyais save profilename
Saving current state to profile /home/root/scripts/net/profilename ...
done.

From that on you can have as many profiles in any place, and work directly with them. If you want to switch profiles back use:

root@localhost:/# yyais switch profilename
Switching to profile /home/root/scripts/net/profilename ...
done.

It also allows for some nifty operations on many tables/chains in one sweep. And has a "start" and "stop" routines where you can tune up your main firewall routines, for example I have added a simple qdisc.

It autodetects the location of every external program it uses with the exception of "which". You should check its path is correct for your distro in the configuration section (there are two other tunables as of now, being the default policy and verbose mode). Anyway, if any external program (including which) is not found the script will refuse to run.

For instructions, run it with "?" or "help". Has to be run as root of course.

Hope you enjoy it, and any comments/criticism/oblivion/etc are welcome, thanks!

Only for Bash 4, sorry!

Version 3.4 @pastie.org
Version 3.5 @pastie.org

Code:

#!/bin/bash

# BASICS -----------------------------------------------------------------------
# shell options: extended globbing
shopt -qs extglob

# global arrays: script metadata, user config, user commands
declare -Ax script config calltable
script[version]='3.5'
script[name]="${0##*/}"
script[pid]=$$
script[cmd_prefix]='cmd:'
script[verb_levels]='debug info status warning error critical fatal'
script[verb_override]=3
script[external_programs]='which iptables iptables-save iptables-restore tc sysctl readlink sed sort'

# USER CONFIG -----------------------------------------------------------------
# make sure this contains the path for "which", otherwise the script will abort
# in doubt type "which which"
config[which]='/usr/bin/which'

# the rest of the values are case insensitive

# default policy when not specified
# values: accept|drop
config[policy]='accept'

# verbosity level: increment to see more output
# 1:warnings, 2:status, 3:information, 4=debug messages
# error, critical and fatal messages ignore this value, and stop execution
config[verbosity]=2

# EXPOSED FUNCS ----------------------------------------------------------------
cmd1:help() {
    IFS="\n" _msg<<HELP
${script[name]} version ${script[version]}

Iptables helper

Usage: ${script[name]} ${script[valid_commands]// /|}

    help
        Shows a help screen.

    start [profiles]
        Initializes the firewall according to configuration, optionally loading profiles.

    stop
        Removes any iptables state and configuration, and disables forwarding.

    switch <profile>
        Switches iptables configuration to the specified profile.

    load <profiles>
        Load the specified profile(s) into the iptables configuration preserving existing rules.

    save [-f] <profile>
        Stores current iptables configuration and state into a profile. The -f switch causes to
        overwrite an existing profile, otherwise an overwrite attempt triggers an error.

    flush [tables] [chains]
        Flushes (removes all rules) in the specified tables and/or chains.

    zero [tables] [chains]
        Zeroes packet counters in the specified tables and/or chains.

    user [tables]
        Flushes (removes) all user-defined chains in the specified tables.

    clear [tables]
        Equivalent to calling flush+zero+user in sequence.

    policy [tables] [chains] [policy]
        Sets default policy for the specified tables and/or chains.

    Notes on [tables], [chains] and [policy] arguments:
        *) All these arguments are optional, case-insensitive and can appear in any order.
        *) Policy can be one of DROP or ACCEPT, defaulting to user configuration.
        *) Whenever a [tables] or [chains] argument is completely missing, the default is to INCLUDE all tables or chains.
        *) Tables and chains are comma-delimited lists, without spaces.
        *) All the commands that operate with these arguments currently IGNORE bogus strings.

    Notes on profiles:
        *) When multiple profiles are expected they can be separated by comma or space.
        *) By default, profiles are loaded or stored from/to the same directory of this script.
          To specify another location, prepend a relative or absolute path to the profile name.
HELP
}

cmd2:start() {
    _status "${script[name]} ${script[version]} starting..."

    # clear iptables configuration and state, set everything to default policy
    _call clear
    _call policy

    # forward any arguments to "load"
    (( $# )) && {
        _info "a request to load profiles has been received"
        _call load $@
    }

    _status "entering user section..."
    # --------------------------------------------------------------------------
    # ADD YOUR START UP COMMANDS HERE ------------------------------------------
    # --------------------------------------------------------------------------

    # enable kernel forwarding
    $_sysctl -w net.ipv4.ip_forward=1

    # simple qdisc to optimize ethernet
    $_tc qdisc add dev eth0 root tbf rate 256kbit latency 50ms burst 1540

    # here I force my output filter to accept
    _call policy output filter accept

    # --------------------------------------------------------------------------
    # ADD YOUR START UP COMMANDS HERE ------------------------------------------
    # --------------------------------------------------------------------------
    _status 'finished starting process.'
}

cmd3:stop() {
    (( $# )) && _error "extra arguments"

    _status "${script[name]} ${script[version]} stopping..."

    # clear iptables configuration and state, set everything to default policy
    _call clear
    _call policy

    _status "entering user section..."
    # --------------------------------------------------------------------------
    # ADD YOUR SHUTDOWN COMMANDS HERE ------------------------------------------
    # --------------------------------------------------------------------------

    # turn off kernel forwarding
    $_sysctl -w net.ipv4.ip_forward=0

    # remove ethernet qdisc
    $_tc qdisc del dev eth0 root
   
    # --------------------------------------------------------------------------
    # ADD YOUR SHUTDOWN COMMANDS HERE ------------------------------------------
    # --------------------------------------------------------------------------
    _status 'finished stopping process.'
}

cmd4:switch() {
    (( ! $# )) && _error "<profile> expected"
    (( $# > 1 )) && _error "extra arguments"

    local file=$(_getprofile "$1")
    [[ ! -f "$file" ]] && _error "file not found: $file"

    _status "Switching to profile $file ..."
    $_iptables_restore < "$file"
    _status 'done switch.'
}

cmd5:load() {
    (( ! $# )) && _error "at least one <profile> expected"

    _status "loading profiles..."
    local file
    for file in ${@//,/ }; do
        file=$(_getprofile "$file")
        [[ ! -f "$file" ]] && _error "file not found: $file"

        _info "profile $file"
        $_iptables_restore -n < "$file"
    done
    _status 'done loading.'
}

cmd6:save() {
    (( ! $# )) && _error "<profile> expected"
    (( $# > 1 )) && _error "extra arguments"

    local file overwrite arg
    for arg in $@; do
        [[ "$arg" == '-f' ]] && overwrite='yes' || file=$(_getprofile "$arg")
    done

    [[ -f "$file" ]] && {
        [[ ! $overwrite ]] && _error "file \"$file\" already exists.\\\nIf you want to overwrite it try again with -f"
        _warning "file \"$file\" already exists, but will overwrite as requested."
    }

    _status "saving current state to $file ..."
    $_iptables_save > "$file"
    _status 'done saving.'
}

cmd7:flush() {
    _status 'flushing builtin chains...'
    _tbchain flush $@
    _status 'done flushing builtin chains.'
}

cmd8:zero() {
    _status 'zeroing counters...'
    _tbchain zero $@
    _status 'done zeroing counters.'
}

cmd9:user() {
    _status 'flushing user chains...'
    _tbchain user $@
    _status 'done flushing user chains.'
}

cmd10:clear() {
    _call flush $@
    _call zero $@
    _call user $@
}

cmd11:policy() {
    _status 'setting policies...'

    # default policy: user-defined
    local policy="${config[policy]^^}" arg

    # get argument policy
    for arg in $@; do
        [[ "${arg^^}" =~ (ACCEPT|DROP) ]] && policy="${arg^^}" && continue
    done
 
    # set policies
    _tbchain policy $policy $@
   
    _status 'done setting policies.'
}

# INTERNAL FUNCS ---------------------------------------------------------------

# returns a full path to a profile, starting from an ambiguous path/profile
# argument
_getprofile() {
    [[ "$1" =~ ^(/|./|../).* ]] && $_readlink -f "$1" || $_readlink -f "${script[directory]}/$1"
}

# process a command in some table(s) and chain(s)
_tbchain() {
    local -A tables
    local action="$1" arg table chain chainarg
    shift

    # get arguments
    for arg in $@; do
        [[ "${arg^^}" =~ (FILTER|NAT|MANGLE|RAW) ]] && {
            while IFS='' read -rd',' table; do
                tables[$table]=''
            done <<< "${arg,,},"
            continue
        }
        [[ "${arg^^}" =~ (INPUT|OUTPUT|FORWARD|PREROUTING|POSTROUTING) ]] && chainarg="${arg^^}" && continue
    done

    # default tables: all tables
    (( ! "${#tables[@]}" )) && tables=([filter]='' [nat]='' [mangle]='' [raw]='')
   
    # default chains: all chains
    [[ ! "$chainarg" ]] && chainarg="INPUT OUTPUT FORWARD PREROUTING POSTROUTING"

    # ensure that chains are defined only at tables where they exist
    for table in ${!tables[@]}; do
        while read chain; do
            [[ "$chainarg" =~ ($chain) ]] && tables[$table]="$chain ${tables[$table]}"
        done< <($_iptables -L -t $table | $_sed -n 's/^Chain \(.*\) (.*$/\1/p')
    done
   
    # apply actions on selected tables and chains
    for table in ${!tables[@]}; do
        for chain in ${tables[$table]}; do
            case $action in
                policy)
                    # note that $policy is local to policy() but we inherit as
                    # in this case we're its child! that puzzled me for a while
                    # morale: beware with locals inheritance!!!
                    _info "$table $chain $policy"
                    $_iptables -t $table -P $chain $policy
                    ;;
                flush)
                    _info "$table $chain"
                    $_iptables -t $table -F $chain
                    ;;
                zero)
                    _info "$table $chain"
                    $_iptables -t $table -Z $chain
                    ;;
                user)
                    _info "$table"
                    $_iptables -t $table -X
                    continue 2
                    ;;
            esac
        done
    done
}

_msg() {
    # for 3.6 this function will get a complete rewrite
    # stdin probably will be the only input for message text, and $@
    # will be just for parameters (as god intended ??) hehe
    # proper management/options for stream redir, colors, escapes, etc
    # will be stuff put in place here

    # use params for messages with header
    (( $# )) && {
        echo -e "${script[name]} (${script[pid]}): $@"
        return
    }

    # read messages from stdin
    local stuff
    while read stuff; do
        echo -e "$stuff"
    done
}

# calls exposed functions internally via lookup table
_call() {
    local command="$1"
    shift
    ${calltable[$command]} $@
}

_init() {
    # used in eval expansions
    local macro

    # shortcut functions for messages:
    # visibility is determined @rt by config[verbosity] + script[verb_override]
    # non overridable levels include an exit with corresponding errlevel
    local verbosity level=0
    for verbosity in ${script[verb_levels]}; do
        IFS="" read -d '' macro <<MACRO
        _$verbosity() {
            (( \${config[verbosity]} + $level > ${script[verb_override]} || $level > ${script[verb_override]} )) &&  _msg <<< "${verbosity}: \"\$@\"";
            $( (( $level > ${script[verb_override]} )) && echo "exit $(( level - ${script[verb_override]} ));" )
        }
MACRO
        eval "$macro"
        (( level++ ))
    done

    # globals with validated full path to external programs:
    # we include "which" too for the case the user lefts it misconfigured
    local program path
    macro=''
    for program in ${script[external_programs]}; do
        path="$( ${config[which]} "$program" )"
        [[ ! -x "$path" ]] && _fatal "\"$program\" could not be found or is not executable. Aborting."

        # sanitize varname and spaces in path, push expr into to the macro
        # for varname rules see bash manual, DEFINITIONS section, "name" paragraph
        macro="_${program//@([![:alnum:]])/_}=\"${path// /\ }\"; $macro"
    done
    eval "$macro"

    # find functions named after pattern ${script[cmd_prefix]}. An optional
    # index can be used before the last character of the pattern to aid the
    # help system to sort the commands for presentation.

    # would liked a single datastruct (ie ordered hash) to contain sorted funcs
    # along with the mappings of command<->realfunc, but couldn't do it, so the
    # options were RT overhead at _call() and/or string manips (even) weirder
    # than these below

    # alternatively I could decouple user-cmd/help hinting from funcnames and
    # just use pure hashes. Less nice, less "automatic", IMO...
    # trades: (space|static|verbose config) vs (cpu|dynamic|verbose code)
    # hope for suggestions
    local index command function
    while IFS=" " read index command function; do
        # lookup table mapping cmd names to functions
        calltable[$command]="$function"

        # sorted list of functions exposed as user commands
        # the conditional handles intermixed indexed/non-indexed commands
        (( 10#$index )) && script[valid_commands]="$command${script[valid_commands]:+ ${script[valid_commands]}}" \
                        || script[valid_commands]="${script[valid_commands]:+${script[valid_commands]} }$command"

    done< <(declare -F | $_sed -nr "s/.*(${script[cmd_prefix]%%?}([0-9]*)${script[cmd_prefix]: -1}(.*))/0\2 \3 \1/p" | $_sort -rg)

    # get the script directory
    script[directory]="$($_readlink -f "${0%/*}")"
}

# START ------------------------------------------------------------------------

# initial stuff
_init

# command loop
while IFS="\n" read command; do
    case "$command" in
        "") _msg <<< 'try with ?' ;;
        \?) _msg <<< "valid commands: ${script[valid_commands]}" ;;
        @(${script[valid_commands]// /|})?(+([[:space:]])*)) _call $command ;;
        *) _error "invalid command: $command\\\nto see available commands: ${script[name]} ?" ;;
    esac
done <<< "$@"


Thor_2.0 11-05-2011 01:40 PM

Hey there!

Thanks for this thread! This is stuff I can learn something from :D

Juako 11-05-2011 03:25 PM

Tanks man! glad you like it :)

TB0ne 11-05-2011 04:42 PM

Agree with Thor 2.0...thanks very much for sharing. Good work.

Juako 11-05-2011 07:19 PM

Quote:

Originally Posted by TB0ne (Post 4516810)
Agree with Thor 2.0...thanks very much for sharing. Good work.

Thanks a lot! Is good to know it's valuable to you fellows


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