Free open firewall software for linux

Simple Firewall is a easy tool for administration users and access control. This tool is made for Linux. Using iptables for packet filtering Write in perl Save rules with xml. That can be run in bash shell and web interface via webmin.
Enhancements:
- Perform reconfigure squid conf for all linux distros
- Fix script init for all linux distros
- Add new menu vpn
- Implemet and integrated PPTP VPN Software
- Modified install script

IPCop project implements existing technology, secure programming practices and outstanding new concepts to make it the Linux Distribution for protecting single home computers, to large corporate networks from intrusions and attacks.

Whether for your home, or SOHO, IPCop will scale to fit your needs. IPCop has even been rumoured to be implemented and protecting larger, more complex networks too. See the IPCop MissionStatement for more information on our goals.

Linux Firewall is a robust, well-designed firewall for Linux 2.4 based on netfilter/iptables. The Projectfiles.com Linux Firewall is the swiss army knife of Linux firewall software. Based on the netfilter-iptables tools, the firewall is a single shell executable written in bash with configuration options and basic documentation included in the same file. It is designed for use with all types of systems: workstations, routers, and servers, and includes advanced features for expert users and Internet Service Providers.

Here are some installation tips:

1. Download the latest rc.firewall [wget http://projectfiles.com/firewall/rc.firewall]
2. Edit the options at the beginning of the file with your favorite text editor. The script comes pre-configured to deny all incoming connections. This is suitable for a typical workstation installation. Refer to the configuration page for in depth explanation of available options.
3. Make the script executable [chmod +x ./rc.firewall]
4. Become root [su]
5. Run the script [./rc.firewall]
6. After you verify that the firewall runs without errors, you may want it to be run automatically on boot. To accomplish this, move the script to the appropriate startup script directory for your distribution [/etc/rc.d/ for Slackware, /etc/init.d/ for Gentoo] and add the following lines in your startup scripts at some point after your ethernet interfaces are configured [for example /etc/rc.d/rc.local for Slackware, and /etc/conf.d/local.start for Gentoo].

Slackware
if [ -x /etc/rc.d/rc.firewall ]; then
/etc/rc.d/rc.firewall
fi
Gentoo
if [ -x /etc/init.d/rc.firewall ]; then
/etc/init.d/rc.firewall
fi

See forum for alternate installation methods.
7. If you are using this firewall on a machine to which you do not have physical access, but can reboot remotely (for example a collocated server or a Linux router at a computer illiterate friends house), you might want to think about putting in a short delay between the time the machine boots and the initialization of the firewall. This would give you a chance to log in and disable the firewall [chmod -x] if something goes wrong. A good example might be if you have the script configured to allow you to connect from a specific remote IP address and your address changes. If you choose to implement this idea, it can be done with the following code in rc.local:

if [ -x /etc/rc.d/rc.firewall ]; then
sleep 30 && /etc/rc.d/rc.firewall | logger -t rc.firewall &
echo "Firewall init in 30 seconds. Check syslog for results."
fi

SINUS project is a application which assess the potential of security without obscurity.
The SINUS Firewall is a TCP/IP packet filter for the Linux operating system. It is distributed under the GNU General Public Licence and comes with complete source code, as the Linux operating system does.
The SINUS firewall is a free and easy way to protect your network from the malware of the Internet. It does not guarantee perfect security, however it comes with a wealth of features, including:
Filtering of all header fields in the IP, TCP, UDP, ICMP, IGMP packets.
Intelligent RIP and FTP support.
Easy to understand, text-based configuration.
Graphical management interface for configuration of several firewalls.
Dynamic rules, including counters and time-outs.
Extensive logging, alerting, and counter intelligence.
Prevention of packet and address spoofing - GNU GPL license.
To install the software, you need a Linux 2.0.x based system. We suggest you install a bare-bone system without X or any of the other nifty features which tend to have security holes. You should not install user accounts on the firewall system. Log-ins other than from the console should be forbidden (if you absolutely have to log in remotely, we strongly suggest you install a copy of ssh).
Although the software has been subject to thorough testing, and has been continuously running without crashes for over 12 months, we are confident someone will eventually unconver A BUG in the software. Therefore, it is version "0.1".
Please do not use this software as the sole means to protect your top secret data. This software is intended for:
People who want to study firewalls
People who dont trust their current firewall
People who currently dont have any protection at all (even if there are serious bugs, it cannot get worse, can it?)
Enhancements:
- NEW FEATURES
- user level authentification between firewall and management interface
- compiles and runs on libc6 (glibc2) systems.
- CHANGES
- management interface now written as Java application (JDK 1.1.6)
- detect land attack
- changed name from sf to sifi (SINUS firewall) due to change of maintainer (now Harald Weidner ).
- BUG FIXES
- TCP RST of established connections now pass through the firewall
- fixed a segfault bug in the passive FTP code

Turtle Firewall is a software which allows you to realize a Linux firewall in a simply and fast way.
Turtle Firewall project is based on Kernel 2.4.x and Iptables. Its way of working is easy to understand: you can define the different firewall elements (zones, hosts, networks) and then set the services you want to enable among the different elements or groups of elements.
You can do this simply editing a XML file or using the comfortable web interface Webmin.
Turtle Firewall is an Open Source project written using the perl language and realeased under GPL version 2.0 by Andrea Frigido (Frisoft).
Main features:
- ZONES, NETWORKS, HOSTS and GROUPS definitions.
- Filter rules definitions based on services.
- New services definitions.
- NAT
- Masquerading

NATting SOHO firewall is a firewall script for iptables.

# Model NATting SOHO firewall for SP article
# by Jay Beale (jay@bastille-linux.org)
#
# Warning: youre going to have to hack this for your own purposes.
#

# Assumptions:
# your internal network is 192.168.1.0/24 on eth1
# your internet IP is 10.0.0.1 on eth0
# your internal network IP on eth1 is 192.168.1.1
#
# Additonally:
# you have another internal network, a DMZ: 192.168.2.0/24 on eth2

$INTERNAL_IP = 192.168.1.1
$INTERNAL_NET = 192.168.1.0/24

$INTERNET = 10.0.0.1

$DMZ = 192.168.2.0/24

# Insert the required kernel modules
modprobe iptable_nat
modprobe ip_conntrack
modprobe ip_conntrack_ftp

# Set default policies for packets going through this firewall box

iptables -t nat -P PREROUTING DROP
iptables -t nat -P POSTROUTING DROP
iptables -P FORWARD DROP

# Set default policies for packet entering this box

iptables -P OUTPUT ALLOW
iptables -P INPUT ALLOW

# Kill spoofed packets

for f in /proc/sys/net/ipv4/conf/*/rp_filter; do
echo 1 > $f
done

# Anything coming from our internal network should have only our addresses!
iptables -A FORWARD -i eth1 -s ! $INTERNAL_NET -j DROP

# Anything coming from the Internet should have a real Internet address
iptables -A FORWARD -i eth0 -s 192.168.0.0/16 -j DROP
iptables -A FORWARD -i eth0 -s 172.16.0.0/12 -j DROP
iptables -A FORWARD -i eth0 -s 10.0.0.0/8 -j DROP

# Note:There are more "reserved" networks, but these are the classical ones.

# Block outgoing network filesharing protocols that arent designed
# to leave the LAN

# SMB / Windows filesharing
iptables -A FORWARD -p tcp --sport 137:139 -j DROP
iptables -A FORWARD -p udp --sport 137:139 -j DROP
# NFS Mount Service (TCP/UDP 635)
iptables -A FORWARD -p tcp --sport 635 -j DROP
iptables -A FORWARD -p udp --sport 635 -j DROP
# NFS (TCP/UDP 2049)
iptables -A FORWARD -p tcp --sport 2049 -j DROP
iptables -A FORWARD -p udp --sport 2049 -j DROP
# Portmapper (TCP/UDP 111)
iptables -A FORWARD -p tcp --sport 111 -j DROP
iptables -A FORWARD -p udp --sport 111 -j DROP

# Block incoming syslog, lpr, rsh, rexec...
iptables -A FORWARD -i eth0 -p udp --dport syslog -j DROP
iptables -A FORWARD -i eth0 -p tcp --dport 515 -j DROP
iptables -A FORWARD -i eth0 -p tcp --dport 514 -j DROP
iptables -A FORWARD -i eth0 -p tcp --dport 512 -j DROP

###
# Transparently proxy all web-surfing through Squid box

$SQUID = 192.168.1.2:8080
$SQUIDSSL = 192.168.1.2:443
iptables -t nat -A PREROUTING -i eth1 -tcp --dport 80 -j DNAT --to $SQUID
iptables -t nat -A PREROUTING -i eth1 -tcp --dport 443 -j DNAT --to $SQUIDSSL

# Transparently forward all outgoing mail to a relay host

$SMTP = 192.168.1.3
iptables -t nat -A PREROUTING -i eth1 -tcp --dport 25 -j DNAT --to $SMTP

# Transparently redirect web connections from outside to the DMZ web
# server

$DMZ_WEB = 192.168.2.2
iptables -t nat -A PREROUTING -i eth0 -d 192.168.1.1 -dport 80 -j DNAT --to $DMZ_WEB

# Source NAT to get Internet traffic through
iptables -t nat -A POSTROUTING -o eth1 -j SNAT --to $INTERNET


# Activate the forwarding!
echo 1 >/proc/sys/net/ipv4/ip_forward

redWall is a bootable CD-ROM Firewall. redWall Firewalls goal is to provide a feature rich firewall solution, with the main goal, to provide a webinterface for all the logfiles generated!
Main features:
- Configuration is currenty stored on a floppy/USB Memory Stick/Harddrive or sent by email (see todo !)
- Due the fact, that most reporting functionality is done via mysql (except for the squid reports), its possible to use the cd as a Mangagement/Logging Console for other firewalls running in your environment using the same cd! Take snort for instance.. you can have 10 firewalls :) running snort, reporting back to the main database on the management/Logging system, in order to have a central "overview" of all your firewalls... Using the SAME CD !! Its all up to you how you configure your firewall and/or Management box !
- based on redhat 9.0
- bridging support
- Mail Virusscanning, spamfiltering and gateway functionality
- /etc is writable (tmpfs) feeded by the configuration medium
- /var is writable (ramdisk or harddisk) (you are not going to run squid on a ramdisk... arent you ?)
- The cd will (at least it should) detect all your network cards (using kudzu) during the initial boot
- During the initial boot, you can setup some basic things like IP Address, Services to start (all disabled by default) and so on
Enhancements:
- A whole lot of new features have been added.
- vuurmuur has been installed again.
- The initial setup has been rewritten to be like a step-by-step configuration.
- A webmin module for openvpn has been added.
- A comprehensive reverse proxy called vultureng has been added.
- Major bugfixes have been applied.

Old Laptop As Firewall is a single, 1440kb floppy Linux with 16-bit PCMCIA support and PPP for using a Pentium I/II laptop to firewall a dial-up connection.
The floppy is msdos-formatted and uses Syslinux to boot into a 4MB ramdisk with a Minix version 2 filesystem. The system was compiled with uClibc 0.9.28.
Main features:
- 2.4.34 non-modular kernel, compressed with lzma
- uClibc 0.9.28
- busybox 1.4.1
- pcmcia-cs 3.2.8
- pppd 2.4.4b1
- iptables 1.3.7
- dnsmasq 2.35
- 100 kb free on the floppy to add more programs!
Version restrictions:
- OLAF has not been tested with more than one computer behind
- the firewall (I only have two boxes to work with.)
- The supplied chat script probably wont work for many people.
- There currently isnt any support for local timezones.
- The Windows and Mac support is lacking; I dont have
- either OS to work with.
Enhancements:
- The file permissions in /etc/* were changed from 0600 to 0644 on all plain text files except gshadow, shadow, and ppp/pap-secrets.
- The file permissions on /bin/busybox were changed from 0700 to 0755.
- The original permissions were too strict for dnsmasq, which runs as user nobody and couldnt access /etc/hosts.