Commit | Line | Data |
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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 | |
33 | done | |
34 | ||
35 | ## Certainly don't allow ping to broadcast addresses. | |
36 | run iptables -A check-icmp -g forbidden \ | |
37 | -p icmp --icmp-type echo-request \ | |
38 | -m addrtype --dst-type BROADCAST | |
39 | ||
40 | m4_divert(58)m4_dnl | |
41 | ## Other ICMP is basically benign, we claim. | |
42 | run iptables -A check-icmp -j ACCEPT | |
43 | ||
44 | ## Done. | |
45 | for i in INPUT FORWARD; do | |
46 | run iptables -A $i -p icmp -j check-icmp | |
47 | done | |
48 | ||
49 | m4_divert(-1) | |
50 | ###----- That's all, folks -------------------------------------------------- |