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#!/bin/bash ### BEGIN INIT INFO # Provides: iptables_firewall # Required-Start: $local_fs $network # Required-Stop: $local_fs # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: iptables firewall initialisation # Description: Initializes rules for iptables ### END INIT INFO IPTABLES="/sbin/iptables" case "$1" in start) echo "Initializing firewall..." # Logging options. #------------------------------------------------------------------------------ LOG="LOG --log-level debug --log-tcp-sequence --log-tcp-options" LOG="$LOG --log-ip-options" # Defaults for rate limiting #------------------------------------------------------------------------------ RLIMIT="-m limit --limit 3/s --limit-burst 30" # Default policies. #------------------------------------------------------------------------------ # Drop everything by default. $IPTABLES -P INPUT DROP $IPTABLES -P FORWARD DROP $IPTABLES -P OUTPUT DROP # Set the nat/mangle/raw tables' chains to ACCEPT $IPTABLES -t nat -P PREROUTING ACCEPT $IPTABLES -t nat -P OUTPUT ACCEPT $IPTABLES -t nat -P POSTROUTING ACCEPT $IPTABLES -t mangle -P PREROUTING ACCEPT $IPTABLES -t mangle -P INPUT ACCEPT $IPTABLES -t mangle -P FORWARD ACCEPT $IPTABLES -t mangle -P OUTPUT ACCEPT $IPTABLES -t mangle -P POSTROUTING ACCEPT # Cleanup. #------------------------------------------------------------------------------ # Delete all $IPTABLES -F $IPTABLES -t nat -F $IPTABLES -t mangle -F # Delete all $IPTABLES -X $IPTABLES -t nat -X $IPTABLES -t mangle -X # Zero all packets and counters. $IPTABLES -Z $IPTABLES -t nat -Z $IPTABLES -t mangle -Z # Custom user-defined chains. #------------------------------------------------------------------------------ # LOG packets, then ACCEPT. $IPTABLES -N ACCEPTLOG $IPTABLES -A ACCEPTLOG -j $LOG $RLIMIT --log-prefix "FW-ACCEPT " $IPTABLES -A ACCEPTLOG -j ACCEPT # LOG packets, then DROP. $IPTABLES -N DROPLOG $IPTABLES -A DROPLOG -j $LOG $RLIMIT --log-prefix "FW-DROP " $IPTABLES -A DROPLOG -j DROP # LOG packets, then REJECT. # TCP packets are rejected with a TCP reset. $IPTABLES -N REJECTLOG $IPTABLES -A REJECTLOG -j $LOG $RLIMIT --log-prefix "FW-REJECT " $IPTABLES -A REJECTLOG -p tcp -j REJECT --reject-with tcp-reset $IPTABLES -A REJECTLOG -j REJECT # Only allows RELATED ICMP types # (destination-unreachable, time-exceeded, and parameter-problem). # TODO: Rate-limit this traffic? # TODO: Allow fragmentation-needed? # TODO: Test. $IPTABLES -N RELATED_ICMP $IPTABLES -A RELATED_ICMP -p icmp --icmp-type destination-unreachable -j ACCEPT $IPTABLES -A RELATED_ICMP -p icmp --icmp-type time-exceeded -j ACCEPT $IPTABLES -A RELATED_ICMP -p icmp --icmp-type parameter-problem -j ACCEPT $IPTABLES -A RELATED_ICMP -j DROPLOG # Make It Even Harder To Multi-PING $IPTABLES -A INPUT -p icmp -m limit --limit 1/s --limit-burst 2 -j ACCEPT $IPTABLES -A OUTPUT -p icmp -j ACCEPT # Only allow the minimally required/recommended parts of ICMP. Block the rest. #------------------------------------------------------------------------------ # Allow all ESTABLISHED ICMP traffic. $IPTABLES -A INPUT -p icmp -m state --state ESTABLISHED -j ACCEPT $RLIMIT $IPTABLES -A OUTPUT -p icmp -m state --state ESTABLISHED -j ACCEPT $RLIMIT # Allow some parts of the RELATED ICMP traffic, block the rest. $IPTABLES -A INPUT -p icmp -m state --state RELATED -j RELATED_ICMP $RLIMIT $IPTABLES -A OUTPUT -p icmp -m state --state RELATED -j RELATED_ICMP $RLIMIT # Allow incoming ICMP echo requests (ping), but only rate-limited. $IPTABLES -A INPUT -p icmp --icmp-type echo-request -j ACCEPT $RLIMIT # Allow outgoing ICMP echo requests (ping), but only rate-limited. $IPTABLES -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT $RLIMIT # Drop any other ICMP traffic. $IPTABLES -A INPUT -p icmp -j DROPLOG $IPTABLES -A OUTPUT -p icmp -j DROPLOG $IPTABLES -A FORWARD -p icmp -j DROPLOG # Selectively allow certain special types of traffic. #------------------------------------------------------------------------------ # Allow loopback interface to do anything. $IPTABLES -A INPUT -i lo -j ACCEPT $IPTABLES -A OUTPUT -o lo -j ACCEPT # Allow incoming connections related to existing allowed connections. $IPTABLES -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # Allow outgoing connections EXCEPT invalid $IPTABLES -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # Miscellaneous. #------------------------------------------------------------------------------ # Explicitly drop invalid incoming traffic $IPTABLES -A INPUT -m state --state INVALID -j DROP # Drop invalid outgoing traffic, too. $IPTABLES -A OUTPUT -m state --state INVALID -j DROP # If we would use NAT, INVALID packets would pass - BLOCK them anyways $IPTABLES -A FORWARD -m state --state INVALID -j DROP # Erlaube bestimmte ausgehende Anfragen (OUTPUT), blocke den Rest #------------------------------------------------------------------------------ # DNS OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p udp --dport 53 -j ACCEPT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 53 -j ACCEPT # HTTP OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT # HTTPS OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 443 -j ACCEPT # SMTP OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 25 -j ACCEPT # SMTPS OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 465 -j ACCEPT # Erlaube ausgehende "submission" (RFC 2476) Anfragen. $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 587 -j ACCEPT # POP3S OUTPUT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 995 -j ACCEPT # IMAP OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 143 -j ACCEPT # IMAPS OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 993 -j ACCEPT # SSH OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 22 -j ACCEPT # FTP OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 21 -j ACCEPT # SMB OUTPUT #$IPTABLES -A OUTPUT -p udp -m multiport --destination-port 137,138 -d 192.168.1.0/24 -j ACCEPTLOG #$IPTABLES -A OUTPUT -p tcp -m multiport --destination-port 139,445 -d 192.168.1.0/24 -j ACCEPTLOG # NFS OUTPUT #$IPTABLES -A OUTPUT -m state --state NEW -p udp --dport 111 -j ACCEPT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 111 -j ACCEPT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 2049 -j ACCEPT #$IPTABLES -A OUTPUT -m state --state NEW -p udp --dport 2049 -j ACCEPT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 32764:32769 -j ACCEPT #$IPTABLES -A OUTPUT -m state --state NEW -p udp --dport 32764:32769 -j ACCEPT # NTP OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p udp --dport 123 -j ACCEPT # WHOIS OUTPUT $IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 43 -j ACCEPT # CVS OUTPUT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 2401 -j ACCEPT # MySQL OUTPUT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 3306 -j ACCEPT # rsync OUTPUT $IPTABLES -A OUTPUT -p tcp --dport 873 -m state --state NEW -d 192.168.1.0/24 -j ACCEPT # SVN OUTPUT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 3690 -j ACCEPT # Mumble OUTPUT #$IPTABLES -A OUTPUT -m state --state NEW -p tcp --dport 64738 -j ACCEPT #$IPTABLES -A OUTPUT -m state --state NEW -p udp --dport 64738 -j ACCEPT # Erlaube bestimmte eingehende Anfragen (INPUT), blocke den Rest #------------------------------------------------------------------------------ # DNS INPUT #$IPTABLES -A INPUT -m state --state NEW -p udp --dport 53 -j ACCEPT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 53 -j ACCEPT # HTTP INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT # HTTPS INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 443 -j ACCEPT # Webmin, INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 10000 -j ACCEPT # POP3 INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 110 -j ACCEPT # IMAP4 INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 143 -j ACCEPT # POP3S INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 995 -j ACCEPT # SMTP INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 25 -j ACCEPT # SSH INPUT $IPTABLES -A INPUT -m state --state NEW -p tcp --dport 22 -j ACCEPT # FTP INPUT #modprobe ip_conntrack_ftp #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 21 -j ACCEPT # FTPS INPUT (ebenfalls FTP erlauben) # Port-Range ist konfigurationsabhaengig (s. /etc/proftpd/proftpd.conf, PassivePorts) #$IPTABLES -A INPUT -p tcp --sport 1024: --dport 52500:52510 -m state --state NEW -j ACCEPT #$IPTABLES -A OUTPUT -p tcp --sport 52500:52510 --dport 1024: -m state --state NEW -j ACCEPT # SMB INPUT #$IPTABLES -A INPUT -p udp -m multiport --destination-port 137,138 -s 192.168.1.0/24 -j ACCEPTLOG #$IPTABLES -A INPUT -p tcp -m multiport --destination-port 139,445 -s 192.168.1.0/24 -j ACCEPTLOG # NFS INPUT # Achtung: Erfordert Rekonfiguration der Dienste (s. https://wiki.debian.org/SecuringNFS) #$IPTABLES -A INPUT -p udp -m multiport --dport 111 -s 192.168.1.0/24 -j ACCEPT #$IPTABLES -A INPUT -p tcp -m multiport --dport 111 -s 192.168.1.0/24 -j ACCEPT #$IPTABLES -A INPUT -p udp -m multiport --dport 2049 -s 192.168.1.0/24 -j ACCEPT #$IPTABLES -A INPUT -p tcp -m multiport --dport 2049 -s 192.168.1.0/24 -j ACCEPT #$IPTABLES -A INPUT -p udp -m multiport --dport 32764:32769 -s 192.168.1.0/24 -j ACCEPT #$IPTABLES -A INPUT -p tcp -m multiport --dport 32764:32769 -s 192.168.1.0/24 -j ACCEPT # Mumble INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 64738 -j ACCEPT #$IPTABLES -A INPUT -m state --state NEW -p udp --dport 64738 -j ACCEPT # MySQL INPUT #$IPTABLES -A INPUT -m state --state NEW -p tcp --dport 3306 -j ACCEPT # rsync INPUT (pruefen) #$IPTABLES -A INPUT -p tcp --dport 873 -m state --state NEW,ESTABLISHED -s 192.168.1.0/24 -j ACCEPT # DHCP INPUT #$IPTABLES -A INPUT -p udp --dport 67 -J ACCEPTLOG # Explicitly log and reject everything else. #------------------------------------------------------------------------------ # Use REJECT instead of REJECTLOG if you don't need/want logging. $IPTABLES -A INPUT -j REJECT $IPTABLES -A OUTPUT -j REJECT $IPTABLES -A FORWARD -j REJECT # Exit gracefully. #------------------------------------------------------------------------------ echo "Firewall initialized and active." ;; stop) echo "Flushing iptables rules..." sleep 1 iptables -F iptables -X iptables -t nat -F iptables -t nat -X iptables -t mangle -F iptables -t mangle -X iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT echo "Firewall stopped." ;; *) echo "Usage: /etc/init.d/iptables_init {start|stop}" exit 2 esac exit 0 |