Unix security refers to the means of securing a Unix or Unix-like operating system. A secure environment is achieved not only by the design concepts of these operating systems, but also through vigilant user and administrative practices.
iptables is a user-space utility program that allows a system administrator to configure the IP packet filter rules of the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized in different tables, which contain chains of rules for how to treat network traffic packets. Different kernel modules and programs are currently used for different protocols; iptables applies to IPv4, ip6tables to IPv6, arptables to ARP, and ebtables to Ethernet frames.
Netfilter is a framework provided by the Linux kernel that allows various networking-related operations to be implemented in the form of customized handlers. Netfilter offers various functions and operations for packet filtering, network address translation, and port translation, which provide the functionality required for directing packets through a network and prohibiting packets from reaching sensitive locations within a network.
Shorewall is an open source firewall tool for Linux that builds upon the Netfilter (iptables/ipchains) system built into the Linux kernel, making it easier to manage more complex configuration schemes by providing a higher level of abstraction for describing rules using text files.
Linux Virtual Server (LVS) is load balancing software for Linux kernel–based operating systems.
FireHOL is a shell script designed as a wrapper for iptables written to ease the customization of the Linux kernel's firewall netfilter.
Linux IP Firewalling Chains, normally called ipchains, is free software to control the packet filter or firewall capabilities in the 2.2 series of Linux kernels. It superseded ipfirewall, but was replaced by iptables in the 2.4 series. Unlike iptables, ipchains is stateless.
ipfirewall or ipfw is a FreeBSD IP, stateful firewall, packet filter and traffic accounting facility. Its ruleset logic is similar to many other packet filters except IPFilter. ipfw is authored and maintained by FreeBSD volunteer staff members. Its syntax enables use of sophisticated filtering capabilities and thus enables users to satisfy advanced requirements. It can either be used as a loadable kernel module or incorporated into the kernel; use as a loadable kernel module where possible is highly recommended. ipfw was the built-in firewall of Mac OS X until Mac OS X 10.7 Lion in 2011 when it was replaced with the OpenBSD project's PF. Like FreeBSD, ipfw is open source. It is used in many FreeBSD-based firewall products, including m0n0wall and FreeNAS. A port of an early version of ipfw was used since Linux 1.1 as the first implementation of firewall available for Linux, until it was replaced by ipchains. A modern port of ipfw and the dummynet traffic shaper is available for Linux and Microsoft Windows. wipfw is a Windows port of an old (2001) version of ipfw.
Harald Welte (1979), also known as LaForge, is a German programmer.
The Netlink socket family is a Linux kernel interface used for inter-process communication (IPC) between both the kernel and userspace processes, and between different userspace processes, in a way similar to the Unix domain sockets. Similarly to the Unix domain sockets, and unlike INET sockets, Netlink communication cannot traverse host boundaries. However, while the Unix domain sockets use the file system namespace, Netlink processes are usually addressed by process identifiers (PIDs).
NuFW is a software package that extends Netfilter, the Linux kernel-internal packet filtering firewall module. NuFW adds authentication to filtering rules. NuFW is also provided as a hardware firewall, in the EdenWall firewalling appliance. NuFW has been restarted by the FFI and renamed into UFWI.
Sentry Firewall is a free open-source network firewall Linux distribution that was first published in 2001 and has been the subject of multiple magazine reviews. The distribution is particularly notable because it consists solely of a bootable CD-ROM that is designed to be used in a computer with no hard disk. Configuration information is retrieved at boot time by automatically searching on an attached floppy disk drive, USB flash memory drive, or another server on the local network willing to provide the configuration.
Zeroshell is a small open-source Linux distribution for servers and embedded systems which aims to provide network services. Its administration relies on a web-based graphical interface; no shell is needed to administer and configure it. Zeroshell is available as Live CD and CompactFlash images, and VMware virtual machines.
Fail2Ban is an intrusion prevention software framework that protects computer servers from brute-force attacks. Written in the Python programming language, it is able to run on POSIX systems that have an interface to a packet-control system or firewall installed locally, for example, iptables or TCP Wrapper.
Uncomplicated Firewall (UFW) is a program for managing a netfilter firewall designed to be easy to use. It uses a command-line interface consisting of a small number of simple commands, and uses iptables for configuration. UFW is available by default in all Ubuntu installations after 8.04 LTS.
Nimbus is a toolkit that, once installed on a cluster, provides an infrastructure as a service cloud to its client via WSRF-based or Amazon EC2 WSDL web service APIs. Nimbus is free and open-source software, subject to the requirements of the Apache License, version 2.
nftables is a subsystem of the Linux kernel providing filtering and classification of network packets/datagrams/frames. It has been available since Linux kernel 3.13 released on 19 January 2014.
Endian Firewall is an open-source router, firewall and gateway security Linux distribution developed by the South Tyrolean company Endian. The product is available as either free software, commercial software with guaranteed support services, or as a hardware appliance.
firewalld is a firewall management tool for Linux operating systems. It provides firewall features by acting as a front-end for the Linux kernel's netfilter framework. firewalld's current default backend is nftables. Prior to v0.6.0, iptables was the default backend. Through its abstractions firewalld acts as an alternative to nft and iptables command line programs. The name firewalld adheres to the Unix convention of naming system daemons by appending the letter "d".
