############################################################################### # The MIT License # # Copyright 2012-2014 Jakub Jirutka . # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the "Software"), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in # all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN # THE SOFTWARE. # ############################################################################### # # Basic ip6tables/IPv6 template for an ordinary servers # # This file is in iptables-restore format. See the man pages for # ip6tables-restore(8) and ip6tables-save(8). # # The following is a set of firewall rules that should be applicable to Linux # servers running within departments. It is intended to provide a useful # starting point from which to devise a comprehensive firewall policy for # a host. # # Parts 1 and 3 of these rules are the same for each host, whilst part 2 can be # populated with rules specific to particular hosts. # # This template is based on http://jdem.cz/v64a3 from University of Leicester. # # For the newest version go to https://gist.github.com/jirutka/3742890. # # @author Jakub Jirutka # @version 1.3.1 # @date 2014-01-28 # ############################################################################### # 1. COMMON HEADER # # # # This section is a generic header that should be suitable for most hosts. # ############################################################################### *filter # Base policy :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] # Don't attempt to firewall internal traffic on the loopback device. -A INPUT -i lo -j ACCEPT # Continue connections that are already established or related to an established # connection. -A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT # Drop non-conforming packets, such as malformed headers, etc. -A INPUT -m conntrack --ctstate INVALID -j DROP # Block remote packets claiming to be from a loopback address. -A INPUT -s ::1/128 ! -i lo -j DROP # Chain for preventing SSH brute-force attacks. # Permits 10 new connections within 5 minutes from a single host then drops # incomming connections from that host. Beyond a burst of 100 connections we # log at up 1 attempt per second to prevent filling of logs. -N SSHBRUTE -A SSHBRUTE -m recent --name SSH --set -A SSHBRUTE -m recent --name SSH --update --seconds 300 --hitcount 10 -m limit --limit 1/second --limit-burst 100 -j LOG --log-prefix "ip6tables[SSH-brute]: " -A SSHBRUTE -m recent --name SSH --update --seconds 300 --hitcount 10 -j DROP -A SSHBRUTE -j ACCEPT # Chain for preventing ping flooding - up to 6 pings per second from a single # source, again with log limiting. Also prevents us from ICMP REPLY flooding # some victim when replying to ICMP ECHO from a spoofed source. -N ICMPFLOOD -A ICMPFLOOD -m recent --set --name ICMP --rsource -A ICMPFLOOD -m recent --update --seconds 1 --hitcount 6 --name ICMP --rsource --rttl -m limit --limit 1/sec --limit-burst 1 -j LOG --log-prefix "ip6tables[ICMP-flood]: " -A ICMPFLOOD -m recent --update --seconds 1 --hitcount 6 --name ICMP --rsource --rttl -j DROP -A ICMPFLOOD -j ACCEPT ############################################################################### # 2. HOST SPECIFIC RULES # # # # This section is a good place to enable your host-specific services. # ############################################################################### # Accept HTTP and HTTPS #-A INPUT -p tcp -m multiport --dports 80,443 --syn -m conntrack --ctstate NEW -j ACCEPT ############################################################################### # 3. GENERAL RULES # # # # This section contains general rules that should be suitable for most hosts. # ############################################################################### # Accept worldwide access to SSH and use SSHBRUTE chain for preventing # brute-force attacks. -A INPUT -p tcp --dport 22 --syn -m conntrack --ctstate NEW -j SSHBRUTE # Permit needed ICMP packet types for IPv6 per RFC 4890. -A INPUT -p ipv6-icmp --icmpv6-type 1 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 2 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 3 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 4 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 133 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 134 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 135 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 136 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 137 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 141 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 142 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 130 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 131 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 132 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 143 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 148 -j ACCEPT -A INPUT -p ipv6-icmp --icmpv6-type 149 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 151 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 152 -j ACCEPT -A INPUT -s fe80::/10 -p ipv6-icmp --icmpv6-type 153 -j ACCEPT # Permit IMCP echo requests (ping) and use ICMPFLOOD chain for preventing ping # flooding. -A INPUT -p ipv6-icmp --icmpv6-type 128 -j ICMPFLOOD # Do not log packets that are going to ports used by SMB # (Samba / Windows Sharing). -A INPUT -p udp -m multiport --dports 135,445 -j DROP -A INPUT -p udp --dport 137:139 -j DROP -A INPUT -p udp --sport 137 --dport 1024:65535 -j DROP -A INPUT -p tcp -m multiport --dports 135,139,445 -j DROP # Do not log packets that are going to port used by UPnP protocol. -A INPUT -p udp --dport 1900 -j DROP # Do not log late replies from nameservers. -A INPUT -p udp --sport 53 -j DROP # Good practise is to explicately reject AUTH traffic so that it fails fast. -A INPUT -p tcp --dport 113 --syn -m conntrack --ctstate NEW -j REJECT --reject-with tcp-reset # Prevent DOS by filling log files. -A INPUT -m limit --limit 1/second --limit-burst 100 -j LOG --log-prefix "ip6tables[DOS]: " COMMIT