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775bd287 | 1 | ### -*-sh-*- |
bfdc045d MW |
2 | ### |
3 | ### ICMP filtering for firewall scripts | |
4 | ### | |
5 | ### (c) 2008 Mark Wooding | |
6 | ### | |
7 | ||
8 | ###----- Licensing notice --------------------------------------------------- | |
9 | ### | |
10 | ### This program is free software; you can redistribute it and/or modify | |
11 | ### it under the terms of the GNU General Public License as published by | |
12 | ### the Free Software Foundation; either version 2 of the License, or | |
13 | ### (at your option) any later version. | |
14 | ### | |
15 | ### This program is distributed in the hope that it will be useful, | |
16 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ### GNU General Public License for more details. | |
19 | ### | |
20 | ### You should have received a copy of the GNU General Public License | |
21 | ### along with this program; if not, write to the Free Software Foundation, | |
22 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
23 | ||
24 | m4_divert(50)m4_dnl | |
25 | ###-------------------------------------------------------------------------- | |
26 | ### ICMP filtering. | |
27 | ||
28 | clearchain check-icmp | |
29 | ||
30 | ## Ping needs inspecting on a host-by-host basis. | |
31 | for type in echo-request echo-reply; do | |
32 | run iptables -A check-icmp -p icmp --icmp-type $type -j RETURN | |
8b021091 | 33 | run ip6tables -A check-icmp -p icmpv6 --icmpv6-type $type -j RETURN |
bfdc045d MW |
34 | done |
35 | ||
8b021091 MW |
36 | ## Certainly don't allow ping to broadcast or multicast addresses. |
37 | case $forward in | |
38 | 1) | |
39 | run iptables -A FORWARD -g forbidden \ | |
40 | -p icmp --icmp-type echo-request \ | |
41 | -m addrtype --dst-type BROADCAST | |
42 | run iptables -A FORWARD -g forbidden \ | |
43 | -p icmp --icmp-type echo-request \ | |
44 | -d 224.0.0.0/8 | |
45 | run ip6tables -A FORWARD -g forbidden \ | |
46 | -p icmpv6 --icmpv6-type echo-request \ | |
47 | -d ff00::/16 | |
48 | ;; | |
49 | esac | |
bfdc045d MW |
50 | |
51 | m4_divert(58)m4_dnl | |
52 | ## Other ICMP is basically benign, we claim. | |
8b021091 | 53 | run ip46tables -A check-icmp -j ACCEPT |
bfdc045d MW |
54 | |
55 | ## Done. | |
f0033e07 | 56 | for i in $inchains; do run ip46tables -A $i -p icmp -j check-icmp; done |
bfdc045d MW |
57 | |
58 | m4_divert(-1) | |
59 | ###----- That's all, folks -------------------------------------------------- |