#!/bin/sh # # /etc/rc.d/rc.firewall: An example of a semi-STRONG IPFWADM firewall ruleset PATH=/sbin:/bin:/usr/sbin:/usr/bin if [ $# -lt 1 ];then set ppp0; fi iface=$1 shift echo Interface: $iface local=192.168.1 export DEBUG_IPFWADM=1 # testing, wait a bit then clear all firewall rules. # uncomment following lines if you want the firewall to automatically # disable after 10 minutes. # (sleep 600; \ # ipfwadm -I -f; \ # ipfwadm -I -p accept; \ # ipfwadm -O -f; \ # ipfwadm -O -p accept; \ # ipfwadm -F -f; \ # ipfwadm -F -p accept; \ # ) & # Load all required IP MASQ modules # # NOTE: Only load the IP MASQ modules you need. All current IP MASQ modules # are shown below but are commented from loading. # Needed to initially load modules # /sbin/depmod -a # Supports the proper masquerading of FTP file transfers using the PORT method # /sbin/modprobe ip_masq_ftp # Supports the masquerading of RealAudio over UDP. Without this module, # RealAudio WILL function but in TCP mode. This can cause a reduction # in sound quality # /sbin/modprobe ip_masq_raudio # Supports the masquerading of IRC DCC file transfers # #/sbin/modprobe ip_masq_irc # Supports the masquerading of Quake and QuakeWorld by default. This modules is # for for multiple users behind the Linux MASQ server. If you are going to # play Quake I, II, and III, use the second example. # # NOTE: If you get ERRORs loading the QUAKE module, you are running an old # ----- kernel that has bugs in it. Please upgrade to the newest kernel. # #Quake I / QuakeWorld (ports 26000 and 27000) #/sbin/modprobe ip_masq_quake # #Quake I/II/III / QuakeWorld (ports 26000, 27000, 27910, 27960) #/sbin/modprobe ip_masq_quake 26000,27000,27910,27960 # Supports the masquerading of the CuSeeme video conferencing software # #/sbin/modprobe ip_masq_cuseeme #Supports the masquerading of the VDO-live video conferencing software # #/sbin/modprobe ip_masq_vdolive #CRITICAL: Enable IP forwarding since it is disabled by default since # # Redhat Users: you may try changing the options in /etc/sysconfig/network from: # # FORWARD_IPV4=false # to # FORWARD_IPV4=true # echo "1" > /proc/sys/net/ipv4/ip_forward #CRITICAL: Enable automatic IP defragmenting since it is disabled by default # in 2.2.x kernels # # This used to be a compile-time option but the behavior was changed # in 2.2.12 # echo "1" > /proc/sys/net/ipv4/ip_always_defrag # Dynamic IP users: # # If you get your IP address dynamically from SLIP, PPP, or DHCP, enable this # following option. This enables dynamic-ip address hacking in IP MASQ, # making the life with Diald and similar programs much easier. # #echo "1" > /proc/sys/net/ipv4/ip_dynaddr # Specify your Static IP address here. # # If you have a DYNAMIC IP address, you need to make this ruleset understand # your IP address everytime you get a new IP. To do this, enable the # following one-line script. (Please note that the different single and # double quote characters MATTER). # # # DHCP users: # ----------- # If you get your TCP/IP address via DHCP, **you will need ** to enable the # #ed out command below underneath the PPP section AND replace the word # "ppp0" with the name of your EXTERNAL Internet connection (eth0, eth1, # etc). It should be also noted that the DHCP server can change IP # addresses on you. To fix this, users should configure their DHCP client # to re-run the firewall ruleset everytime the DHCP lease is renewed. # # NOTE #1: Some DHCP clients like the older version of "pump" (the newer # versions have been fixed) did NOT have the ability to run # scripts after a lease-renew. Because of this, you need to # replace it with something like "dhcpcd" or "dhclient". # # NOTE #2: The syntax for "dhcpcd" has changed in recent versions. # # Older versions used syntax like: # dhcpcd -c /etc/rc.d/rc.firewall eth0 # # Newer versions use syntax like: # dhcpcd eth0 /etc/rc.d/rc.firewall # # NOTE #3: For Pump users, put the following line in /etc/pump.conf: # # script /etc/rc.d/rc.firewall # # PPP users: # ---------- # If you aren't already aware, the /etc/ppp/ip-up script is always run when # a PPP connection comes up. Because of this, we can make the ruleset go # and get the new PPP IP address and update the strong firewall ruleset. # # If the /etc/ppp/ip-up file already exists, you should edit it and add a line # containing "/etc/rc.d/rc.firewall" near the end of the file. # # If you don't already have a /etc/ppp/ip-up sccript, you need to create the # following link to run the /etc/rc.d/rc.firewall script. # # ln -s /etc/rc.d/rc.firewall /etc/ppp/ip-up # # * You then want to enable the #ed out shell command below * # # # PPP and DHCP Users: # ------------------- # Remove the # on the line below and place a # in front of the line after that. # ppp_ip="`/sbin/ifconfig $iface | grep 'inet addr' | awk '{print $2}' | sed -e 's/.*://'`" # #ppp_ip="your.static.PPP.address" # MASQ timeouts # # 2 hrs timeout for TCP session timeouts # 10 sec timeout for traffic after the TCP/IP "FIN" packet is received # 60 sec timeout for UDP traffic (MASQ'ed ICQ users must enable a 30sec firewall timeout in ICQ itself) # /sbin/ipfwadm -M -s 7200 10 60 ############################################################################# # Incoming, flush and set default policy of reject. Actually the default policy # is irrelevant because there is a catch all rule with deny and log. # /sbin/ipfwadm -I -f /sbin/ipfwadm -I -p reject # local interface, local machines, going anywhere is valid # /sbin/ipfwadm -I -a accept -V $local.1 -S $local.0/24 -D 0.0.0.0/0 # remote interface, claiming to be local machines, IP spoofing, get lost # /sbin/ipfwadm -I -a reject -W $iface -S $local.0/24 -D 0.0.0.0/0 -o # remote interface, any source, going to permanent PPP address is valid # /sbin/ipfwadm -I -a accept -W $iface -S 0.0.0.0/0 -D $ppp_ip/32 # loopback interface is valid. # /sbin/ipfwadm -I -a accept -W lo -S 0.0.0.0/0 -D 0.0.0.0/0 # catch all rule, all other incoming is denied and logged. pity there is no # log option on the policy but this does the job instead. # /sbin/ipfwadm -I -a reject -S 0.0.0.0/0 -D 0.0.0.0/0 -o ############################################################################# # Outgoing, flush and set default policy of reject. Actually the default policy # is irrelevant because there is a catch all rule with deny and log. # /sbin/ipfwadm -O -f /sbin/ipfwadm -O -p reject # local interface, any source going to local net is valid # /sbin/ipfwadm -O -a accept -V $local.1 -S 0.0.0.0/0 -D $local.0/24 # outgoing to local net on remote interface, stuffed routing, deny # /sbin/ipfwadm -O -a reject -W $iface -S 0.0.0.0/0 -D $local.0/24 -o # outgoing from local net on remote interface, stuffed masquerading, deny # /sbin/ipfwadm -O -a reject -W $iface -S $local.0/24 -D 0.0.0.0/0 -o # outgoing from local net on remote interface, stuffed masquerading, deny # /sbin/ipfwadm -O -a reject -W $iface -S 0.0.0.0/0 -D $local.0/24 -o # anything else outgoing on remote interface is valid # /sbin/ipfwadm -O -a accept -W $iface -S $ppp_ip/32 -D 0.0.0.0/0 # loopback interface is valid. # /sbin/ipfwadm -O -a accept -W lo -S 0.0.0.0/0 -D 0.0.0.0/0 # catch all rule, all other outgoing is denied and logged. pity there is no # log option on the policy but this does the job instead. # /sbin/ipfwadm -O -a reject -S 0.0.0.0/0 -D 0.0.0.0/0 -o ############################################################################# # Forwarding, flush and set default policy of deny. Actually the default policy # is irrelevant because there is a catch all rule with deny and log. # /sbin/ipfwadm -F -f /sbin/ipfwadm -F -p deny # Masquerade from local net on local interface to anywhere. # /sbin/ipfwadm -F -a masquerade -W ppp0 -S $local.0/24 -D 0.0.0.0/0 # # catch all rule, all other forwarding is denied and logged. pity there is no # log option on the policy but this does the job instead. # /sbin/ipfwadm -F -a reject -S 0.0.0.0/0 -D 0.0.0.0/0 -o #End of file.