3 ### Utility functions for firewall scripts
5 ### (c) 2008 Mark Wooding
8 ###----- Licensing notice ---------------------------------------------------
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18 ### GNU General Public License for more details.
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22 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
25 ###--------------------------------------------------------------------------
26 ### Utility functions.
28 ## doit COMMAND ARGS...
30 ## If debugging, print the COMMAND and ARGS. If serious, execute them.
33 if [ "$FW_DEBUG" ]; then echo "* $*"; fi
34 if ! [ "$FW_NOACT" ]; then "$@"; fi
39 ## If debugging, print the MESSAGE.
42 if [ "$FW_DEBUG" ]; then echo "$*"; fi
45 ## defport NAME NUMBER
47 ## Define $port_NAME to be NUMBER.
50 eval port_$name=$number
54 ###--------------------------------------------------------------------------
55 ### Basic chain constructions.
57 ## ip46tables ARGS ...
59 ## Do the same thing for `iptables' and `ip6tables'.
66 ## clearchain CHAIN CHAIN ...
68 ## Ensure that the named chains exist and are empty.
73 *:*) table=${chain%:*} chain=${chain#*:} ;;
76 run ip46tables -t $table -N $chain
80 ## errorchain CHAIN ACTION ARGS ...
82 ## Make a chain which logs a message and then invokes some other action,
83 ## typically REJECT. Log messages are prefixed by `fw: CHAIN'.
88 *:*) table=${chain%:*} chain=${chain#*:} ;;
91 clearchain $table:$chain
92 run ip46tables -t $table -A $chain -j LOG \
93 -m limit --limit 3/minute --limit-burst 10 \
94 --log-prefix "fw: $chain " --log-level notice
95 run ip46tables -t $table -A $chain -j "$@"
99 ###--------------------------------------------------------------------------
100 ### Basic option setting.
102 ## setopt OPTION VALUE
107 opt=$1; shift; val=$*
108 run sysctl -q net/ipv4/$opt="$val"
111 ## setdevopt OPTION VALUE
113 ## Set an IP interface-level sysctl.
116 opt=$1; shift; val=$*
117 for i in /proc/sys/net/ipv4/conf/*; do
119 run sysctl -q net/ipv4/conf/${i#/proc/sys/net/ipv4/conf/}/$opt="$val"
124 ###--------------------------------------------------------------------------
125 ### Packet filter construction.
129 ## Add connection tracking to CHAIN, and allow obvious stuff.
133 run ip46tables -A $chain -p tcp -m state \
134 --state ESTABLISHED,RELATED -j ACCEPT
135 run ip46tables -A $chain -p tcp ! --syn -g bad-tcp
140 ## Add standard IP filtering rules to the CHAIN.
145 ## Pass fragments through, assuming that the eventual destination will sort
146 ## things out properly. Except for TCP, that is, which should never be
148 run iptables -A $chain -p tcp -f -g tcp-fragment
149 run iptables -A $chain -f -j ACCEPT
150 run ip6tables -A $chain -p tcp -g tcp-fragment \
151 -m ipv6header --soft --header frag
152 run ip6tables -A $chain -j ACCEPT \
153 -m frag ! --fragfirst
156 ## allowservices CHAIN PROTO SERVICE ...
158 ## Add rules to allow the SERVICES on the CHAIN.
161 chain=$1 proto=$2; shift 2
168 left=${svc%:*} right=${svc#*:}
169 case $left in *[!0-9]*) eval left=\$port_$left ;; esac
170 case $right in *[!0-9]*) eval right=\$port_$right ;; esac
175 case $svc in *[!0-9]*) eval svc=\$port_$svc ;; esac
179 *: | :* | "" | *[!0-9:]*)
180 echo >&2 "Bad service name"
184 count=$(( $count + $n ))
185 if [ $count -gt 15 ]; then
186 run ip46tables -A $chain -p $proto -m multiport -j ACCEPT \
187 --destination-ports ${list#,}
196 run ip46tables -A $chain -p $proto -m multiport -j ACCEPT \
197 --destination-ports ${list#,}
200 run ip46tables -A $chain -p $proto -j ACCEPT \
201 --destination-port ${list#,}
206 ## ntpclient CHAIN NTPSERVER ...
208 ## Add rules to CHAIN to allow NTP with NTPSERVERs.
213 run iptables -A $chain -s $ntp -j ACCEPT \
214 -p udp --source-port 123 --destination-port 123
220 ## Add rules to allow CHAIN to be a DNS resolver.
225 run ip46tables -A $chain -j ACCEPT \
226 -m state --state ESTABLISHED \
227 -p $p --source-port 53
231 ## openports CHAIN [MIN MAX]
233 ## Add rules to CHAIN to allow the open ports.
237 [ $# -eq 0 ] && set -- $open_port_min $open_port_max
238 run ip46tables -A $chain -p tcp -g interesting --destination-port $1:$2
239 run ip46tables -A $chain -p udp -g interesting --destination-port $1:$2
243 ###--------------------------------------------------------------------------
244 ### Packet classification.
246 ## defbitfield NAME WIDTH
248 ## Defines MASK_NAME and BIT_NAME symbolic constants for dealing with
249 ## bitfields: x << BIT_NAME yields the value x in the correct position, and
250 ## ff & MASK_NAME extracts the corresponding value.
254 eval MASK_$name=$(( (1 << $width) - 1 << $bitindex ))
255 eval BIT_$name=$bitindex
256 bitindex=$(( $bitindex + $width ))
259 ## Define the layout of the bitfield.
265 ## defnetclass NAME FORWARD-TO...
267 ## Defines a netclass called NAME, which is allowed to forward to the
268 ## FORWARD-TO netclasses.
270 ## For each netclass, constants from_NAME and to_NAME are defined as the
271 ## appropriate values in the FROM and TO fields (i.e., not including any mask
274 ## This function also establishes mangle chains mark-from-NAME and
275 ## mark-to-NAME for applying the appropriate mark bits to the packet.
277 ## Because it needs to resolve forward references, netclasses must be defined
278 ## in a two-pass manner, using a loop of the form
280 ## for pass in 1 2; do netclassindex=0; ...; done
288 ## Pass 1. Establish the from_NAME and to_NAME constants, and the
289 ## netclass's mask bit.
290 eval from_$name=$(( $netclassindex << $BIT_FROM ))
291 eval to_$name=$(( $netclassindex << $BIT_TO ))
292 eval _mask_$name=$(( 1 << ($netclassindex + $BIT_MASK) ))
297 ## Pass 2. Compute the actual from and to values. We're a little bit
298 ## clever during source classification, and set the TO field to
299 ## all-bits-one, so that destination classification needs only a single
301 from=$(( ($netclassindex << $BIT_FROM) + (0xf << $BIT_TO) ))
303 eval bit=\$_mask_$net
304 from=$(( $from + $bit ))
306 to=$(( ($netclassindex << $BIT_TO) + \
307 (0xf << $BIT_FROM) + \
308 (1 << ($netclassindex + $BIT_MASK)) ))
309 trace "from $name --> set $(printf %x $from)"
310 trace " to $name --> and $(printf %x $from)"
312 ## Now establish the mark-from-NAME and mark-to-NAME chains.
313 clearchain mangle:mark-from-$name mangle:mark-to-$name
314 run ip46tables -t mangle -A mark-from-$name -j MARK --set-mark $from
315 run ip46tables -t mangle -A mark-to-$name -j MARK --and-mark $to
318 netclassindex=$(( $netclassindex + 1 ))
321 ## defiface NAME NETCLASS:NETWORK/MASK...
323 ## Declares a network interface NAME and associates with it a number of
324 ## reachable networks. During source classification, a packet arriving on
325 ## interface NAME from an address in NETWORK/MASK is classified as coming
326 ## from to NETCLASS. During destination classification, all packets going to
327 ## NETWORK/MASK are classified as going to NETCLASS, regardless of interface
328 ## (which is good, because the outgoing interface hasn't been determined
331 ## As a special case, the NETWORK/MASK can be the string `default', which
332 ## indicates that all addresses not matched elsewhere should be considered.
342 clearchain mangle:in-$name
343 run ip46tables -t mangle -A in-classify -i $name -g in-$name
348 netclass=${item%:*} addr=${item#*:}
352 defaultclass=$netclass
353 run ip46tables -t mangle -A out-classify -g mark-to-$netclass
356 run ip6tables -t mangle -A in-$name -s $addr -g mark-from-$netclass
357 run ip6tables -t mangle -A out-classify -d $addr -g mark-to-$netclass
358 allnets6="$allnets6 $name:$addr"
361 run iptables -t mangle -A in-$name -s $addr -g mark-from-$netclass
362 run iptables -t mangle -A out-classify -d $addr -g mark-to-$netclass
363 allnets="$allnets $name:$addr"
369 ## defvpn IFACE CLASS NET HOST:ADDR ...
371 ## Defines a VPN interface. If the interface has the form `ROOT+' (i.e., a
372 ## netfilter wildcard) then define a separate interface ROOTHOST routing to
373 ## ADDR; otherwise just write a blanket rule allowing the whole NET. All
374 ## addresses concerned are put in the named CLASS.
377 iface=$1 class=$2 net=$3; shift 3
382 name=${host%%:*} addr=${host#*:}
383 defiface $root$name $class:$addr
387 defiface $iface $class:$net
393 ###----- That's all, folks --------------------------------------------------