Pare-feu iptables openwrt IPV4

Note : iptables est remplacé maintenant par nftables

Voir aussi :

LibreCMC

OPNsense

Pour ICMP voir icmp.txt

TODO : Copie sur git

#!/bin/sh # # rc.icmp Advanced ICMP Filtering with iptables # # Version Hx: $Id: rc.icmp,v 1.00 2003/01/28 09:04:10 david Exp $ # $Id: rc.icmp,v 1.01 2013/09/07 16:59:38 david Exp $ # ################################################################ # # # Internet Control Message Protocol (ICMP), documented in RFC # # 792, is a required protocol tightly integrated with IP. ICMP # # messages, delivered in IP packets, are used for out-of-band # # messages related to network operation or misoperation. Since # # ICMP relies on IP, packet delivery is unreliable (as # # opposed to TCP). # # # # ICMP functions typically include : # # - Announce network errors # # - Announce network congestion (source quench) # # - Assist troubleshooting (ping) # # - Announce timeouts (traceroute) # # # # Be cautious; blocking ICMP can have unpredictable results. # # You may find that your TCP/IP connectivity may break. # # # # A good resource for ICMP filtering can be found at: # # www.oregontechsupport.com/articles/ICMP_Scanning_v3.0.pdf # # # # Netfilter (iptables) can implement the ICMP Extension by # # name (e.g., "host unreachable"), numeric type (e.g., "3"), # # or a numeric type and code separated by a "/" (e.g., "3/3"). # ################################################################ ################################################################ # ICMP echo-reply (type 0) # # # # Ping scanning is typically used to determine which hosts on # # a network are up. Typically this is done by sending ICMP # # ECHO request packets to the target host. # ################################################################ iptables -A OUTPUT -p icmp --icmp-type 0 -j ACCEPT iptables -A INPUT -p icmp --icmp-type 0 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 0 -j ACCEPT ################################################################ # ICMP types 1-2 are unassigned # ################################################################ ################################################################ # ICMP destination-unreachable (type 3) # # # # Filtering "fragmentation-needed" traffic is a BAD idea. # # # # Codes # # 0 network-unreachable # # 1 host-unreachable # # 2 protocol-unreachable # # 3 port-unreachable # # 4 fragmentation-needed # # 5 source-route-failed # # 6 network-unknown # # 7 host-unknown # # 8 Source Host Isolated # # 9 network-prohibited # # 10 host-prohibited # # 11 TOS-network-unreachable # # 12 TOS-host-unreachable # # 13 communication-prohibited [RFC1812] # # 14 host-precedence-violation [RFC1812] # # 15 precedence-cutoff [RFC1812] # ################################################################ iptables -A INPUT -p icmp --icmp-type 3/4 -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type 3/4 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 3/4 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 3/3 -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type 3/3 -j ACCEPT iptables -A INPUT -p icmp --icmp-type 3/3 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 3/1 -j ACCEPT iptables -A INPUT -p icmp --icmp-type 3/1 -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type 3/1 -j ACCEPT ################################################################ # ICMP Source Quench (type 4) # # # # This is detailed in RFC 792. Filtering this type of # # traffic is generally considered a BAD idea. # ################################################################ iptables -A INPUT -p icmp --icmp-type 4 -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type 4 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 4 -j ACCEPT ################################################################ # ICMP Redirect (type 5) # # # # Codes # # 0 Redirect Datagram for the Network (or subnet) # # 1 Redirect Datagram for the Host # # 2 Redirect Datagram for the Type of Service and Network # # 3 Redirect Datagram for the Type of Service and Host # ################################################################ if [ -f /proc/sys/net/ipv4/conf/all/accept_redirects ]; then echo " Kernel ignores all ICMP redirects" echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects fi ################################################################ # ICMP Alternate Host Address (type 6) # # ICMP Unassigned (type 7) # ################################################################ ################################################################ # ICMP Echo Request (type 8) # ################################################################ iptables -A INPUT -p icmp --icmp-type 8 -m limit --limit 2/s -j ACCEPT iptables -A INPUT -p icmp --icmp-type 8 -j LOG --log-prefix "ICMP/in/8 Excessive: " iptables -A INPUT -p icmp --icmp-type 8 -j DROP iptables -A OUTPUT -p icmp --icmp-type 8 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 8 -j ACCEPT if [ -f /proc/sys/net/ipv4/icmp_echo_ignore_all ]; then echo " Kernel answers ICMP Echo requests" echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all fi ################################################################ # Prevention: Smurf IP Denial-of-Service Attacks # # # # See http://www.cert.org/advisories/CA-1998-01.html # ################################################################ if [ -f /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts ]; then echo " Kernel ignores ICMP Echo requests sent to broadcast/multicast addresses" echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts fi ################################################################ # ICMP Router Advertisement (type 9) # # ICMP Router Solicitation (type 10) # # # # These are described in RFC 1256. # ################################################################ ################################################################ # ICMP Time Exceeded (type 11) # # # # Codes # # 0 Time to Live exceeded in Transit # # 1 Fragment Reassembly Time Exceeded # ################################################################ iptables -A INPUT -p icmp --icmp-type 11 -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type 11 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 11 -j ACCEPT ################################################################ # ICMP Parameter Problem (type 12) # # # # Codes # # 0 Pointer indicates the error # # 1 Missing a Required Option [RFC1108] # # 2 Bad Length # ################################################################ iptables -A INPUT -p icmp --icmp-type 12 -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type 12 -j ACCEPT iptables -A FORWARD -p icmp --icmp-type 12 -j ACCEPT ################################################################ # ICMP Timestamp (type 13) # # ICMP Timestamp Reply (type 14) # # ICMP Information Request (type 15) # # ICMP Information Reply (type 16) # # ICMP Address Mask Request (type 17) # # ICMP Address Mask Reply (type 18) # # ICMP Reserved (types 19-29) # # ICMP Traceroute (type 30) # # ICMP Datagram Conversion Error (type 31) # ################################################################ ################################################################ # ICMP bogus error responses # # # # Sometimes you will come across routers that send out invalid # # responses to broadcast frames. This is a violation of RFC # # 1122, "Requirements for Internet Hosts -- Communication # # Layers". As a result, these events are logged by the kernel. # # To avoid filling up your logfile with unnecessary clutter, # # you can tell the kernel not to issue these warnings. # ################################################################ if [ -f /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses ]; then echo " Kernel ignores bogus responses to broadcast frames" echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses fi ################################################################ # ICMP Catch-all # # # # There are many more ICMP types than this, but most aren't # # implemented in large-scale (yet). We can safely say that # # anything not specifically allowed above should be blocked. # ################################################################ iptables -A INPUT -p icmp -m limit -j LOG --log-prefix "ICMP/IN: " iptables -A OUTPUT -p icmp -m limit -j LOG --log-prefix "ICMP/OUT: " iptables -A FORWARD -p icmp -m limit -j LOG --log-prefix "ICMP/FWD: " iptables -A INPUT -p icmp -j DROP iptables -A OUTPUT -p icmp -j DROP iptables -A FORWARD -p icmp -j DROP ################################################################ # This document was lovingly handcrafted on a Dell Latitude # # C400 laptop running Slackware Linux 8.1, in case anyone # # asks. # ################################################################ # This work is licensed under a Creative # Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License, # available at http://creativecommons.org/licenses/by-nc-nd/3.0/