Free to reject software for linux

UTIN Firewall script project is a script for Linux 2.4.x and iptables.

###########
# Configuration options, these will speed you up getting this script to
# work with your own setup.

#
# your LANs IP range and localhost IP. /24 means to only use the first 24
# bits of the 32 bit IP adress. the same as netmask 255.255.255.0
#
# INET_IP is used by me to allow myself to do anything to myself, might
# be a security risc but sometimes I want this. If you dont have a static
# IP, I suggest not using this option at all for now but its still
# enabled per default and will add some really nifty security bugs for all
# those who skips reading the documentation=)

LAN_IP="192.168.0.2"
LAN_BCAST_ADRESS="192.168.0.255"
LAN_IFACE="eth1"

LO_IFACE="lo"
LO_IP="127.0.0.1"

INET_IP="194.236.50.155"
INET_IFACE="eth0"

IPTABLES="/usr/local/sbin/iptables"

#########
# Load all required IPTables modules
#

#
# Needed to initially load modules
#
/sbin/depmod -a

#
# Adds some iptables targets like LOG, REJECT and MASQUARADE.
#
/sbin/modprobe ipt_LOG
#/sbin/modprobe ipt_REJECT
/sbin/modprobe ipt_MASQUERADE

#
# Support for owner matching
#
#/sbin/modprobe ipt_owner

#
# Support for connection tracking of FTP and IRC.
#
#/sbin/modprobe ip_conntrack_ftp
#/sbin/modprobe ip_conntrack_irc

#
# Enable ip_forward, this is critical since it is turned off as defaul in
# Linux.
#

echo "1" > /proc/sys/net/ipv4/ip_forward

#
# Dynamic IP users:
#
#echo "1" > /proc/sys/net/ipv4/ip_dynaddr

#
# Enable simple IP Forwarding and Network Address Translation
#

$IPTABLES -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source $INET_IP

#
# Set default policies for the INPUT, FORWARD and OUTPUT chains
#

$IPTABLES -P INPUT DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -P FORWARD DROP

#
# bad_tcp_packets chain
#
# Take care of bad TCP packets that we dont want.
#

$IPTABLES -N bad_tcp_packets
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j LOG
--log-prefix "New not syn:"
$IPTABLES -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP

#
# Do some checks for obviously spoofed IPs
#

$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 192.168.0.0/16 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 10.0.0.0/8 -j DROP
$IPTABLES -A bad_tcp_packets -i $INET_IFACE -s 172.16.0.0/12 -j DROP
$IPTABLES -A bad_tcp_packets -i $LAN_IFACE ! -s 192.168.0.0/16 -j DROP

#
# Bad TCP packets we dont want
#

$IPTABLES -A FORWARD -p tcp -j bad_tcp_packets

#
# Accept the packets we actually want to forward between interfaces.
#

$IPTABLES -A FORWARD -p tcp --dport 21 -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -p tcp --dport 80 -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -p tcp --dport 110 -i $LAN_IFACE -j ACCEPT

$IPTABLES -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG
--log-level DEBUG --log-prefix "IPT FORWARD packet died: "


#
# Create separate chains for ICMP, TCP and UDP to traverse
#

$IPTABLES -N icmp_packets
$IPTABLES -N tcp_packets
$IPTABLES -N udpincoming_packets

#
# The allowed chain for TCP connections
#

$IPTABLES -N allowed
$IPTABLES -A allowed -p TCP --syn -j ACCEPT
$IPTABLES -A allowed -p TCP -m state --state ESTABLISHED,RELATED
-j ACCEPT
$IPTABLES -A allowed -p TCP -j DROP

#
# ICMP rules
#

# Changed rules totally
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 8 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 --icmp-type 11 -j ACCEPT

#
# TCP rules
#

$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 21 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 22 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 80 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 --dport 113 -j allowed

#
# UDP ports
#

$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 53 -j ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 123 -j ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 2074 -j ACCEPT
$IPTABLES -A udpincoming_packets -p UDP -s 0/0 --source-port 4000 -j ACCEPT

#
# INPUT chain
#
# Bad TCP packets we dont want
#

$IPTABLES -A INPUT -p tcp -j bad_tcp_packets

#
# Rules for incoming packets from anywhere
#

$IPTABLES -A INPUT -p ICMP -j icmp_packets
$IPTABLES -A INPUT -p TCP -j tcp_packets
$IPTABLES -A INPUT -p UDP -j udpincoming_packets

#
# Rules for special networks not part of the Internet
#

$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LO_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LAN_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $INET_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -d $INET_IP -m state --state ESTABLISHED,RELATED
-j ACCEPT
$IPTABLES -A INPUT -m limit --limit 3/minute --limit-burst 3
-j LOG --log-level DEBUG --log-prefix "IPT INPUT packet died: "

#
# OUTPUT chain
#
#
# Bad TCP packets we dont want
#

$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets


$IPTABLES -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $INET_IP -j ACCEPT
$IPTABLES -A OUTPUT -m limit --limit 3/minute --limit-burst 3
-j LOG --log-level DEBUG --log-prefix "IPT OUTPUT packet died: "

NAT iptables firewall script is an iptables firewall script.

This script is meant to be run once per boot the rules will be double added if you try to run it twice if you need to add another rule during runtime, change the -A to a -I to add it to the top of the list of rules if you use -A it will go at the end after the reject rule.

Sample:

# interface definitions
BAD_IFACE=eth0

DMZ_IFACE=eth1
DMZ_ADDR=x.x.x.96/28

GOOD_IFACE=eth2
GOOD_ADDR=192.168.1.0/24

MASQ_SERVER=x.x.x.98
FTP_SERVER=x.x.x.100
MAIL_SERVER=x.x.x.99
MAIL_SERVER_INTERNAL=192.168.1.3

# testing
#set -x

ip route del x.x.x.96/28 dev $BAD_IFACE
ip route del x.x.x.96/28 dev $DMZ_IFACE
ip route add x.x.x.97 dev $BAD_IFACE
ip route add x.x.x.96/28 dev $DMZ_IFACE

# we need proxy arp for the dmz network
echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp
echo 1 > /proc/sys/net/ipv4/conf/eth1/proxy_arp

# turn on ip forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward

# turn on antispoofing protection
for f in /proc/sys/net/ipv4/conf/*/rp_filter; do echo 1 > $f; done

# flush all rules in the filter table
#iptables -F

# flush built in rules
iptables -F INPUT
iptables -F OUTPUT
iptables -F FORWARD

# deny everything for now
iptables -A INPUT -j DROP
iptables -A FORWARD -j DROP
iptables -A OUTPUT -j DROP

# make the chains to define packet directions
# bad is the internet, dmz is our dmz, good is our masqed network
iptables -N good-dmz
iptables -N bad-dmz
iptables -N good-bad
iptables -N dmz-good
iptables -N dmz-bad
iptables -N bad-good

iptables -N icmp-acc

# accept related packets
iptables -A FORWARD -m state --state INVALID -j DROP
iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT

# internal client masqing
iptables -t nat -A POSTROUTING -s $GOOD_ADDR -o $BAD_IFACE -j SNAT --to $MASQ_SERVER
# mail server masqing
iptables -t nat -A PREROUTING -p tcp -d $MAIL_SERVER --dport smtp -j DNAT --to $MAIL_SERVER_INTERNAL:25
iptables -t nat -A PREROUTING -p tcp -d $MAIL_SERVER --dport http -j DNAT --to $MAIL_SERVER_INTERNAL:80
iptables -t nat -A PREROUTING -p tcp -d $MAIL_SERVER --dport https -j DNAT --to $MAIL_SERVER_INTERNAL:443
# to allow the above to work you need something like
# iptables -A bad-good -p tcp --dport smtp -d $MAIL_SERVER_INTERNAL -j ACCEPT

# set which addresses jump to which chains
iptables -A FORWARD -s $GOOD_ADDR -o $DMZ_IFACE -j good-dmz
iptables -A FORWARD -s $GOOD_ADDR -o $BAD_IFACE -j good-bad

iptables -A FORWARD -s $DMZ_ADDR -i $DMZ_IFACE -o $BAD_IFACE -j dmz-bad
iptables -A FORWARD -s $DMZ_ADDR -i $DMZ_IFACE -o $GOOD_IFACE -j dmz-good

iptables -A FORWARD -o $DMZ_IFACE -j bad-dmz
iptables -A FORWARD -o $GOOD_IFACE -j bad-good

# drop anything that doesnt fit these
iptables -A FORWARD -j LOG --log-prefix "chain-jump "
iptables -A FORWARD -j DROP

# icmp acceptance
iptables -A icmp-acc -p icmp --icmp-type destination-unreachable -j ACCEPT
iptables -A icmp-acc -p icmp --icmp-type source-quench -j ACCEPT
iptables -A icmp-acc -p icmp --icmp-type time-exceeded -j ACCEPT
iptables -A icmp-acc -p icmp --icmp-type echo-request -j ACCEPT
iptables -A icmp-acc -p icmp --icmp-type echo-reply -j ACCEPT
# iptables -A icmp-acc -j LOG --log-prefix "icmp-acc "
iptables -A icmp-acc -j DROP

# from internal to dmz
iptables -A good-dmz -p tcp --dport smtp -j ACCEPT
iptables -A good-dmz -p tcp --dport pop3 -j ACCEPT
iptables -A good-dmz -p udp --dport domain -j ACCEPT
iptables -A good-dmz -p tcp --dport domain -j ACCEPT
iptables -A good-dmz -p tcp --dport www -j ACCEPT
iptables -A good-dmz -p tcp --dport https -j ACCEPT
iptables -A good-dmz -p tcp --dport ssh -j ACCEPT
iptables -A good-dmz -p tcp --dport telnet -j ACCEPT
iptables -A good-dmz -p tcp --dport auth -j ACCEPT
iptables -A good-dmz -p tcp --dport ftp -j ACCEPT
iptables -A good-dmz -p tcp --dport 1521 -j ACCEPT
iptables -A good-dmz -p icmp -j icmp-acc
iptables -A good-dmz -j LOG --log-prefix "good-dmz "
iptables -A good-dmz -j DROP

# from external to dmz
iptables -A bad-dmz -p tcp --dport smtp -j ACCEPT
iptables -A bad-dmz -p udp --dport domain -j ACCEPT
iptables -A bad-dmz -p tcp --dport domain -j ACCEPT
iptables -A bad-dmz -p tcp --dport www -j ACCEPT
iptables -A bad-dmz -p tcp --dport https -j ACCEPT
iptables -A bad-dmz -p tcp --dport ssh -j ACCEPT
iptables -A bad-dmz -p tcp -d $FTP_SERVER --dport ftp -j ACCEPT
iptables -A bad-dmz -p icmp -j icmp-acc
iptables -A bad-dmz -j LOG --log-prefix "bad-dmz "
iptables -A bad-dmz -j DROP

# from internal to external
iptables -A good-bad -j ACCEPT
# iptables -t nat -A POSTROUTING -o $BAD_IFACE -j SNAT --to $MASQ_SERVER
#iptables -A good-bad -p tcp -j MASQ
#iptables -A good-bad -p udp -j MASQ
#iptables -A good-bad -p icmp -j MASQ
#ipchains -A good-bad -p tcp --dport www -j MASQ
#ipchains -A good-bad -p tcp --dport ssh -j MASQ
#ipchains -A good-bad -p udp --dport 33434:33500 -j MASQ
#ipchains -A good-bad -p tcp --dport ftp -j MASQ
#ipchains -A good-bad -p icmp --icmp-type ping -j MASQ
#ipchains -A good-bad -j REJECT -l

# from dmz to internal
# iptables -A dmz-good -p tcp ! --syn --sport smtp -j ACCEPT
iptables -A dmz-good -p tcp --dport smtp -j ACCEPT
iptables -A dmz-good -p tcp --sport smtp -j ACCEPT
iptables -A dmz-good -p udp --sport domain -j ACCEPT
iptables -A dmz-good -p tcp ! --syn --sport domain -j ACCEPT
iptables -A dmz-good -p tcp ! --syn --sport www -j ACCEPT
iptables -A dmz-good -p tcp ! --syn --sport ssh -j ACCEPT
iptables -A dmz-good -p tcp -d 192.168.1.34 --dport smtp -j ACCEPT
iptables -A dmz-good -p icmp -j icmp-acc
iptables -A dmz-good -j LOG --log-prefix "dmz-good "
iptables -A dmz-good -j DROP

# from dmz to external
iptables -A dmz-bad -p tcp --dport smtp -j ACCEPT
iptables -A dmz-bad -p tcp --sport smtp -j ACCEPT
iptables -A dmz-bad -p udp --dport domain -j ACCEPT
iptables -A dmz-bad -p tcp --dport domain -j ACCEPT
iptables -A dmz-bad -p tcp --dport www -j ACCEPT
iptables -A dmz-bad -p tcp --dport https -j ACCEPT
iptables -A dmz-bad -p tcp --dport ssh -j ACCEPT
iptables -A dmz-bad -p tcp --dport ftp -j ACCEPT
iptables -A dmz-bad -p tcp --dport whois -j ACCEPT
iptables -A dmz-bad -p tcp --dport telnet -j ACCEPT
iptables -A dmz-bad -p udp --dport ntp -j ACCEPT
# ipchains -A good-bad -p udp --dport 33434:33500 -j MASQ
iptables -A dmz-bad -p icmp -j icmp-acc
iptables -A dmz-bad -j LOG --log-prefix "dmz-bad "
iptables -A dmz-bad -j DROP

# from external to internal
iptables -A bad-good -p tcp --dport smtp -d $MAIL_SERVER_INTERNAL -j ACCEPT
iptables -A bad-good -p tcp --dport http -d $MAIL_SERVER_INTERNAL -j ACCEPT
iptables -A bad-good -p tcp --dport https -d $MAIL_SERVER_INTERNAL -j ACCEPT
iptables -A bad-good -j LOG --log-prefix "bad-good "
iptables -A bad-good -j REJECT

# rules for this machine itself
iptables -N bad-if
iptables -N dmz-if
iptables -N good-if

# set up the jumps to each chain
iptables -A INPUT -i $BAD_IFACE -j bad-if
iptables -A INPUT -i $DMZ_IFACE -j dmz-if
iptables -A INPUT -i $GOOD_IFACE -j good-if

# external iface
iptables -A bad-if -p icmp -j icmp-acc
iptables -A bad-if -j ACCEPT
#ipchains -A bad-if -i ! ppp0 -j DENY -l
#ipchains -A bad-if -p TCP --dport 61000:65095 -j ACCEPT
#ipchains -A bad-if -p UDP --dport 61000:65095 -j ACCEPT
#ipchains -A bad-if -p ICMP --icmp-type pong -j ACCEPT
#ipchains -A bad-if -j icmp-acc
#ipchains -A bad-if -j DENY

# dmz iface
iptables -A bad-if -p icmp -j icmp-acc
iptables -A dmz-if -j ACCEPT

# internal iface
iptables -A good-if -p tcp --dport ssh -j ACCEPT
iptables -A good-if -p ICMP --icmp-type ping -j ACCEPT
iptables -A good-if -p ICMP --icmp-type pong -j ACCEPT
iptables -A good-if -j icmp-acc
iptables -A good-if -j DROP


# remove the complete blocks
iptables -D INPUT 1
iptables -D FORWARD 1
iptables -D OUTPUT 1

Scam-protect is a milter which restricts the use of your domain address in emails. The aim is to protect your users from phishing by rejecting mail purporting to be from your domain. It is not meant as a replacement for SPF or SenderID.
Main features:
- Reject mail with your domain name in the mail from envelope
- Reject mail with your domain name in the From header
Performance
Scam-protect milter was designed to be light-weight and use minimal resources.
Whitelist
Scam-protect has a configurable whitelist of IP addresses or a range of IP addresses (CIDR). This feature can be used to allow which hosts can use your domain name in email addresses..
Accept mail from users
Users should configure their mail clients (MS Outlook, Eudora, Mozilla Thunderbird) to use the port 587 (MSA) instead of the SMTP port to send mail through the mail server running Scam-protect.
Scam-protect will accept mail if the connection was authenticated through SMTP AUTH.

Return-RST is a firewalling tool for Linux 2.2.xx systems using IPCHAINS. It uses the netlink device to capture packets and sends TCP RST packets in response to TCP connection requests.

Normal IPCHAINS only allows you to drop packets, or reject packets with an ICMP error message. With Return-RST, you can make it look like there is no server listening, rather than giving away that theyre being filtered to the attacker.

Return-RST was written to overcome the lack of an ipchains policy that can return a RESET packet when denying a TCP connection. The DENY policy just drops the packet, and the REJECT policy sends back an ICMP message. Either policy will pull an attacker off to the fact theyre being filtered.

On the other hand, an RST in response to a TCP SYN packet is what happens when there is no server listening on a port - this program allows you to return this error, so attackers will think that there is no server available.

sipscreen project is a Linux iptables QUEUE target handler written in perl for screening incoming SIP phone calls.

If you have a network configuration similar to mine, with a Vonage or other Voice-over-IP adapter located behind a Linux gateway, you may find sipscreen useful for programmatically accepting or rejecting inbound calls, based on the caller ID information, the time of day, or any other clever algorithm you can think of.

BFBTester is great for doing quick, proactive, security checks of binary programs. BFBTester will perform checks for single and multiple argument command line overflows and environment variable overflows. Versions 2.0-BETA and higher can also watch for
tempfile creation activity to alert the user of any programs using unsafe tempfile names.

The basic syntax for making BFBTester to run is:

bfbtester [-htv] [-d level ] [-r rejects] [-o out-file]
[-x max-execs] -asme file [file2 file3 ...]
Must specify one or more of the following tests:
-s Single Argument Test
-m Multiple Argument Test
-e Environment Variable Test
-a Selects all tests
Options:
-h Print this message
-t Enable tempfile monitoring
-v Print version string
-d level Set debug level (default = 0, max = 2)
-r rejects Comma separated list of binaries to skip
-o out-file Output to out-file rather than stdout
-x max-execs Set maximum executables to run in parallel (default = 250)
file. Specific binary or a directory of binaries to test

You must specify at least one test to run and you must specify either a binary or a directory.

Python SRS Library is a Python implementation of the Sender Rewriting Scheme. Python SRS Library is a fairly direct translation of the draft implementation in Perl by Shevek. It includes a test suite, which currently checks four levels of forwarding and subsequent reversal for the Guarded, DB, and Reversible implementations.
This package includes scripts to be used as sendmail program maps. See sendmail integration for an explanation and instructions on incorporating SRS into sendmail.cf, substituting envfrom2srs.py and srs2envtol.py for the perl scripts. Even simpler, use the supplied sendmail m4 hack with sendmail.mc.
SRS.Daemon.Daemon() provides a simple socket daemon suitable for use with the Exim mailer.
RPM now includes a sendmail socketmap daemon. The program map is no longer recommended. It is slow and a security risk. Prior to socketmaps, it was all that was available for a custom map. Socketmap is available in sendmail 8.13.
For best results, use with Python milter to reject unsigned recipients.
Sendmail integration
Add the following lines to your /etc/mail/sendmail.mc (RedHat / Fedora) after any MAILER():
dnl #
dnl # File listing domains we do not SRS encode for when sending to
dnl #
define(`NO_SRS_FILE,`/etc/mail/no-srs-mailers)dnl
dnl #
dnl # Uncomment the following if you do not wish to SRS encode mail from
dnl # local domains. Only non-local domains need to be SRS encoded to
dnl # satisfy SPF. But encoding all outgoing mail can detect bounce forgeries.
dnl #
dnl define(`NO_SRS_FROM_LOCAL)dnl
dnl #
HACK(`pysrs,`/var/run/milter/pysrs)dnl
If you cannot install a version of sendmail with socketmap support, then the original program map is still available as HACK(pysrsprog).
NO_SRS_FILE is the path of a file containing the recipient MTAs for which you wont do SRS (typically, primary MXes for which you are secondary). Just leave this away, if you are secondary for nobody. The no-srs-mailers file is a simple text file which has one recipient MTA per line.
The argument to pysrs is the socket where the socketmap daemon is listening. This must match /etc/mail/pysrs.cfg or the default of /var/run/milter/pysrs.
NO_SRS_FROM_LOCAL : if this is set (define line present), then no SRS is done if sender is local (i.e. his domain is in /etc/mail/local-host-names)
The argument to pysrsprog is the domain that your SRS addresses bear (i.e. if your SRS addresses are srs0=mumble-jumble-toto@mydomain.com, then the argument is mydomain.com). This overrides fwdomain in /etc/mail/pysrs.cfg.
Enhancements:
- This release supports signing mode.

mod_bwshare is a bandwidth throttling and monitoring per client IP address.

The mod_bwshare module accepts or rejects HTTP requests from each client IP address based on past downloads by that client IP address.

If the HTTP clients download rate exceeds specified levels, the reponse to the HTTP client is an HTML warning message.

A human browser will see a warning message indicating how long to wait.

Automatic rampant downloaders will download large numbers of useless warning messages.

The original motivation for mod_bwshare was to prevent automatic download of all 900 MBytes of material on one of my web sites which was connected to a 33k modem, which would have taken several days if it had succeeded.