GuardDog is a firewall configuration utility for KDE. GuardDog is aimed at two groups of users. Novice to intermediate users who are not experts in TCP/IP networking and security, and those users who don't want the hastle of dealing with cryptic shell scripts and ipchains parameter. Read more hot
adcfw-log is a tool for analyzing firewall logs in order to extract meaningful information. It is designed to be a standalone script with very few requirements that can generate different kinds of reports, such as fully formatted reports of what had been logged, with summaries by source or destination host, the type of service, or protocol. There are also options to filter the input data by date, host, protocol, service, and so on.
AGT is a powerful console frontend to iptables, supporting nearly all of the iptables extensions. All options can be specified in a configuration file with similar syntax to 'ipf' and 'ipfw'.
Alfandega Firewall Configurator
Alfandega Firewall Configurator is a dialog based interface to simple configure a netfilter firewall. Itīs provides some configuration profiles that adjusts to most common firewall configurations.
Altimate Firewall is a small and easy-to-use firewall, based on a hardened Gentoo system. It has an intuitive and easy-to-use Web interface.
APSEND is a TCP IP/UDP/ICMP packet sender primarily used to test firewalls and other networking aspects.
Arno's IPTABLES Firewall Script
Arno's IPTABLES Firewall Script is a secure stateful firewall for both single and multi-homed machines. It supports NAT and SNAT, port forwarding, ADSL ethernet modems with both static and dynamically assigned IPs, MAC address filtering, stealth port scan detection, DMZ and DMZ-2-LAN forwarding, protection against SYN/ICMP flooding, and extensive user definable logging with rate limiting to prevent log flooding. It features support for all IP protocols and VPNs such as IPSec. and is easy to configure and highly customizable. A filter script that makes your firewall log more readable is also included.
Automatic Firewall is a script that will automatically configure a firewall for you, with no need for manual configuration on your side, no need to tell it the interfaces, ip addresses and which interface is external or internal.
Bandwidth Management Tools
Bandwidth Management Tools is a total bandwidth management solution for Linux and can be used for firewalling, traffic graphing, and shaping. It is not based on any currently-available bandwidth management software and supports packet queues, bursting, complex traffic flow hierarchies, flow groups, traffic logging, and a simple real-time monitoring front-end.
Bifrost Firewall is a firewall management interface to iptables (iptables GUI).
BlockIt is a perl script based on Guardian which looks in the Snort alert file and puts up IPTables rules.
Borderline is a firewall generator. It takes a generic rule specification as input and generated an highly optimized firewall. It features IPv6 rule generation, support for multiple interfaces, and integrated support for network zones.
brandgang offers Http firewall tunneling for Java applets with restricted network access.
CD-ROM Firewall is a Red Hat/Fedora based firewall that boots off a CD-ROM. Utilizing a headless, diskless computer it can provide services such as network address translation (NAT), virtual private network (VPN), ADSL connnectivity, DHCP, DNS, and many more.
clapf is a modular network filter for postfix. It includes a statistical (inverse chi-square) antispam module, the blackhole feature and antivirus support (clamav, AVG Linux, avast!, Kaspersky and Dr.Web) preventing virus infection as well as a cgi and a command line interface to easily train the token database.
cp2fwbuilder helps you to migrate an existing Checkpoint Firewall 1 Installation and its Rulesets to Linux with iptables or *BSD based Firewall.
DAXFi is a Python script that helps configuring the iptables/netfilter firewall included in Linux kernel 2.4.x.
Deception Toolkit is a toolkit designed to give defenders a couple of orders of magnitude advantage over attackers.
Dr.Morena is a tool to confirm the rule configuration of a firewall.
Dwall is an all-purpose firewall tool to generate an iptables firewall out of a simple configuration. It contains about 80 predefined services and comes with a simple 3 zone firewall example.
DynFw for ipchains
constantly checks /var/log/messages for packets denied
by ipchains and responds by temporarily setting up firewallrules that deny any access from the originating IPs
Easwall is an easy to manage firewall script for unix systems based on the iptables security tool.
an easy-to-use GUI for the console firewall script
ebtables is a filtering tool for a bridging firewall. The filtering is focussed on the Link Layer Ethernet frame fields. Apart from filtering, it also gives the ability to alter the Ethernet MAC addresses and implement a brouter.
Endoshield is a fully configurable easy to use firewall, which will run under the 2.2 Linux kernel (ipchains), or the 2.4 Linux Kernel (iptables). It is aimed at home users who have no knowledge of how to make their own firewalls.
EtherDam is a firewall configuration engine that relies on iptables. It presents firewall configuration as a somewhat simpler scripting language that's still flexible enough for most purposes.
(commercial) fCluster is a multi-threaded client/server redundancy application for your Linux firewall solution. fCluster is designed for the production environment with features that include: dynamic firewall synchronization, support for both ipchains and netfilter, user definable polling intervals and fail-over sequence, and email notification of a system failure.
FERM is a tool to maintain complex firewalls, without having the trouble to rewrite the complex rules over and over again. FERM allows the entire firewall rule set to be stored in a separate file, and to be loaded with one command.
FIAIF is an Intelligent Firewall: provides a highly customizable script for setting up an iptables based firewall. Unlike many other scripts, FIAIF can be truly customized allowing multiple interfaces (or rather zones)
FieryFilter is an interactive desktop firewall for Linux. FF will ask you everytime a new network connection is made if you want to allow or deny it. In future versions you will be able to generate rules from connections and thus minimize the amount of questions you are asked.
Fire-Waller reads your syslog against packet filter rows and creates HTML output of the found rows.
fireflier is a firewall tool, which is built on top of the iptables framework. You can create rules based on single incoming network packets or simply allow/deny single packets to pass. client-server, ssl, timeouting rules, filtering by application.
FireGate is a Linux IPtables script for use as a firewall and NAT/masquerade router for home networks or SOHO applications. It shares access to a single internet connection from multiple workstations, and can optionally forward all inbound HTTP, SMTP or other requests to internal servers (as opposed to a DMZ).
FireHOL is a Linux iptables firewall generator. It's goal is to be extremely abstracted so that the administrators can design firewalls of any complexity without the need to know all the details about protocols, sockets, ports, etc. Read more
Firetable is an IPtables firewall script for Linux. It has no graphical interface, and all the configuration is done via configuration files. This makes Firetable ideal for servers.
Firetero is a firewall for a single computer. Features include: Easy to use: default configuration allows all client programs (browse web, send email...) but denies access to your computer from the Internet, uses iptables syntax: no new language to learn, leverage your existing skills, uses standard /etc/init.d script and keeps configuration in standard place /etc/firetero, and creates human readable firewall (for example, ?iptables -L? output is readable).
Firewall is a set of scripts (firewall, fwup and fwdown) that implement an ipchains firewall and various forms of network address and port translation. All you have to do is read the policy file and edit it to reflect your topology and filtering policy.
Firewall Builder consists of object-oriented GUI and set of policy compilers for various firewall platforms. In Firewall Builder, firewall policy is a set of rules, each rule consists of abstract objects which represent real network objects and services (hosts, routers, firewalls, networks, protocols). Firewall Builder helps user maintain database of objects and allows policy editing using simple drag-and-drop operations.
Firewall Monitor allows you to monitor ipchains/iptables output in realtime. It supports both logging to a file/stdout and/or to tcpdump format capture logs. It also supports security features such as running non-root, and chrooting itself.
Firewall/SOSDG is a Linux Netfilter firewall designed to be simple and effective. Features include NAT support, port forwarding, basic routing/forwarding of packets, and ipv6 firewalling support.
fk is a free software replacement for the TIS fwtk.
flex-fw is a small and fast front-end for the Linux iptables utility
The Firewall Tester (FTester) is a tool designed for testing firewalls filtering policies and Intrusion Detection System (IDS) capabilities.
The tool consists of two perl scripts, a packet injector (ftest) and the listening sniffer (ftestd). The first script injects custom packets, defined in ftest.conf, with a signature in the data part while the sniffer listens for such marked packets.
a module to configure the Linux kernel packet filtering firewall using higher level abstraction than rules on input, output and forward chains. It supports masquerading and accounting as well
fwknop implements network access controls (via iptables) based on a flexible port knocking mini-language, but with a twist; it combines port knocking and passive operating system fingerprinting to make it possible to do things like only allow, say, Linux-2.4/2.6 systems to connect to your SSH daemon.
GajShield SecureGate Firewall
(commercial) GajShield SecureGate is an ICSA certified firewall that provides virus protection, bandwidth management, policy based routing, URL filtering, and a VPN gateway. Its features include stateful packet inspection, deep packet filtering, content filtering, virus detection for HTTP traffic, transparent SMTP and POP3 virus scanning, and IPSec and PPTP VPN tunneling. It blocks spyware, adware, and other malicious applications from entering an organization. It has comprehensive reporting, multi-role administration, and is easy to manage. The virus scanning policy can be defined on a per rule basis.
gfcc is a GTK+ application which can control Linux firewall policies and rules, based on ipchains package.
GfXChains is an ipchains based graphic interface to set firewall policy on a 2.2.x kernel Linux Box.
gnome-lokkit is a user friendly firewall configuration tool for Red Hat Linux. It needs internationalisation and non RH support yet.
GNU Phantom.Security is a computer-controlled security system. Using the software and a simple circuit board (diagram included) that you build, you can create a good basic security system that is computer controlled.
gShield is an iptables firewall for use with the modern series of the Linux kernel. It is easily configurable, and supports a wide range of features. It features: multiple NATs, configurable public service access, access control lists, routable protection, port-forwarding, transparent proxies, and more.
gShieldConf is a small program to edit the gShield configuration files. It is written using the gtk toolkit.
Gtk-IPTables is a gtk-based frontend for iptables written in C.
Gufw is an easy, intuitive, way to manage your Ubuntu firewall powered by ufw.
HardWall Firewall is an iptables script that does the following:- Port Forwarding, Packet Filtering, Statefull Packet Inspection, Port Redirection, Masqurade, SNAT, DNAT, NAT & Bridging - Functions as both a Workstation and IP Forwarding Firewall
The Horatio system is a firewall authentication tool. The horatio server uses syslog to log the actions it takes, including log-ins, log-outs, web accesses, rollcalls, and process starts and stops. The firewall uses Linux ipchains. HTTPS support is provided using OpenSSL, and the Perl modules IO::Socket::SSL, Net::SSLeay, and HTTP::Daemon::SSL. The firewall and host list management scripts are written in Bash.
IDMS Firewall is an easy to use firewall configuration script, featuring statefull connection tracking, bandwidth limiting and bandwidth logging
(commercial) InJoy Firewall is a flexible multi-platform (Linux, Windows 2K/XP, OS/2) firewall for businesses of any size. It offers security, preconfigured policy templates, complete IPSec VPN support, gateway capabilities, intuitive management, access control, many documented deployment examples, and comprehensive documentation.
IP-Array is a Linux iptables firewall script written in bash. It allows the creation of precise, stateful rules, while remaining easy to configure. It supports VPN, traffic shaping (creation of custom HTB and SFQ qdiscs, classes, and filters), multiple LANs, DMZ, NAT, logging, MAC address matching, packet marking, syslog logging, and various sysctl settings.
Ip6wall is a firewall script for ip6tables. It features support for IPV6-mapped LANs, forwarding, port forwarding, configurable outgoing filtering, configurable public service access, access control lists, and more.
IPchains Firewalling Webmin Module
IPchains Firewalling Webmin Module allows you to easily maintain a firewall based on ipchains with the Webmin look and feel. It has three modes: Newbie: select one of five security levels, Template: Define from a table with protocols and directions what should be allowed to pass your firewall, Expert: Have the real ipchains experience by having every parameter under control. This edits a script file which all ipchains rules.
ipfreeze manages the rules insertion in the running kernel and launches ipfreeze.pl. This perl script listens on the netlink device for packets that are passed by the firewall (QUEUE target). If a packet is sent, ipfreeze get the source IP and insert a new rule in the firewall that will destroy every packets coming from that IP.
ipfwadm2ipchains is a script designed to convert ipfwadm rulesets into ipchains rulesets.
ipkungfu is an iptables-based Linux firewall. The primary design goals are security, ease of use, and performance, in that order.
ipmenu is a user interface to Netfilter/iptables, allowing you to edit firewall rules.
ipmkchains reads in a set of rule files, computes the differences between those rules and the rules that are currently in use, and executes the necessary commands to make the
rules in use match the rules from the file.
ips-qos is a flexible firewall and traffic shaping tool. It works on Fedora Core, CentOS, Debian, Ubuntu, Slackware, Mandriva, PLD, and SUSE. It was intended to give administrators more control over a shared Internet connection. It includes ips, a flexible and easy-to-use configurable firewall with the ability to control access to the Internet (or selected services) from a LAN. It also includes qos, a traffic shaping tool that measures and controls the traffic load for every computer in a LAN.
ipset-bash-completion is programmable completion code for the bash shell, to support the ipset program. It allows you to interactively retrieve and complete options, commands, set names, types, and members.
IPShutter lets you firewall off ports such as ssh, and selectively enable access with a one-time password. For example, if you want to log into the server from a friend's house, you pull out a list of one-time passwords and point the web browser at a URL that contains one password.
ipt_ACCOUNT is a high performance local network accounting system written for the Linux netfilter/iptables system.
Ipt_fw is a firewall for Linux based on iptables. It is designed for client systems. Ipt_fw outputs a shell script containing iptables commands, so inspection of the settings it creates is easy.
ipt_sysrq is an iptables target that allows you to do the same as the magic sysrq key on a keyboard does, but over the network.
iptables is an enhancement on ipchains, and is used to control packet filtering, Network Address Translation (masquerading, portforwarding, transparent proxying), and special effects. Read more
iptables-control is a fast and easy iptables filter configurator It features a step-by-step interactive configurator script, a TCP/UDP ports configurator, LAN settings for routing and masquerading, and ICMP filtering.
iptables-p2p is an iptables match module capable of matching various peer-to-peer networks by examining the application-layer protocol.
isinglass-hzd is a firewall setup script designed to protect dial-up users. It protects a user's system against security holes in programs user may not even know are running.
ITVal is an analysis tool for evaluating iptables firewall systems which provides an easy way for a system administrator to verify that his firewall provides the protection he thinks it does. ITVal can analyze multiple NAT'd firewalls connected serially
kfirewall is a small GUI application witch allows you to handle ipchains or ipfwadm rules.
KMyFirewall is an IPTables based firewall configuration tool for the KDE Desktop Environment running on Linux based systems.
Knetfilter is a KDE application designed to manage the netfilter functionalities that come with the kernels 2.4 and later.
KnutWall is an advanced iptables firewall. You don't need any prior iptables experience to set up KnutWall. All the configuration is done from a separate configuration file where you select what network interfaces to use, what ports to open, etc.
levy is a perl script which generates a basic iptables rulesets based on a given external interface and a set of ports to open. Its design is to save folks some time in creating a skeleton ruleset to work from, though it can construct a fully functional firewall with NAT support.
links2world Firewall is a very simple tool writen in C, that helps you generate iptables rules for Linux 2.4.x and newer kernels. Released under GNU General Public License, it is very easy to configure and designed to run on hosts with one or more network interfaces.
Linux IP Firewalling Chains
Linux IP Firewalling Chains is an update to (and hopefully an improvement upon) the 2.0 Linux Firewalling code, for the 2.2 Linux kernel.
LinuxMagic VPN Firewall
LinuxMagic VPN Firewall is a firewall kit that uses built-in 128 Bit Encryption, IPSEC-compatible VPN standards, and a 'no-write' design.
LutelWall is a Linux IPtables shell script written in bash for use as a stateful firewall and NAT/masquerade router for single or multiple subnets networks. It shares access to a internet connection from multiple workstations.
Mason is a tool that interactively builds a firewall using Linux' ipfwadm or ipchains firewalling. You leave mason running on the firewall machine while you are making all the kinds of connections that you want the firewall to support (and want it to block).
mmtcpfwd is a secure TCP/IP port forwarder superserver intended for linux firewalls.
MultiGate provides an easy and integrated solution designed to secure and protect networks. MultiGate contains SecurityPlugins that allow quick installation, configuration and operation of various Open Source security modules designed to enhance security and protection capabilities of the gateway.
myfw is a firewall based on iptables snipets (modules). It helps you to build your iptables firewall.
netfico is a complete Linux/netfilter (iptables) firewall and gateway configuration tool. It takes over the complete process of brining upi the network interfaces, configuring VLANs, setting IP addresses, setting routes and configure the netfilter/iptables rules.
netfilter is a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. A registered callback function is then called back for every packet that traverses the respective hook within the network stack. Read more
Netfilter2html is a script developed in AWK for filtering netfilter/iptables logs to generate HTML reports.
NetSecL-Firewall is an iptables script that protects against stealth scans, port scans, OS fingerprints, and other types of scanning.
NetSPoC is a tool for security managment of large computer networks with different security domains. It generates configuration files for packet filters controlling the borders of security domains.
nfacct is a command line utility used to create, retrieve, and delete Netfilter accounting objects.
Open Edgewize (previously Sphirewall) is a highly flexible firewall/router that provides user based management, application layer filtering, and everything else you would expect from a enterprise grade firewall.
Pachyderm-fw is a graphical firewall management software for Ipchains. Based on MySQL & PHP. Easy to use, powerful, lots of configuration abilities etc.
packet2sql converts any text file/log file which contains ipchains packet logs into a stream of SQL inserts which can be used as the base for a firewall-analyzing database application.
Packetflow Firewall Generator
PacketFlow Firewall Generator is an XML-based firewall generator. It takes an XML configuration file that defines the firewall policy and generates a list of iptables commands to implement this policy. It is primarily intended for use on dedicated firewalls, but it can be used in other scenarios. It makes dealing with many interfaces easy. PacketFlow works on the concept of interface "security levels." New connections are allowed to flow down hill from interfaces with a high security level to interfaces with a low security level. This approach tends to make rule sets much shorter, even with many interfaces. Access lists allow you to override the default behavior of the security levels. Access lists are defined between interfaces. There is also support for incoming, outgoing, and wildcard access lists. Wildcard access lists allow you to easily allow new connections to a particular service from any interface.
pasmal is a TCP/IP packet authentication system. When it receives a sequence of ICMP or TCP packets to any port (open/closed), it will issue a command on the server.
PCX Firewall is a perl script which works with several configuration files to generate 3 shell scripts (startfw, stopfw, and restartfw) which actually do the real work of the firewall.
PMFirewall is an Ipchains Firewall and Masquerading Configuration Utility for Linux. It was designed to allow a beginner to build a custom firewall with little or no ipchains experience.
Portsmith is an application-based firewall that is designed to interact with authorized users, and offers an easy-to-use browser driven interface. Portsmith's unique features include its core logic and its interface. Its logic specifies that ports are kept in a closed position until an authorized user logs into the Portsmith interface and triggers them open. When opened, the ports are only accessible from the authorized user's current IP address.
Pyroman is a firewall config tool for complex networks. By using iptables-restore, it's much faster than other tools in configuring the firewall, the configuration is simple, and it has accurate error reporting and offers rollback of changes.
Quarantine firewall is yet another firewall that has masquerade, type-of-service, and traffic shaping features.
quicktables is an iptables firewall and firewall / nat (gateway) script generator. it was created to provide a secure set of iptables rules quickly, while still maintaining vew requirements (sh and ifconfig pretty much). quicktables will ask you to answer a small handful of questions, and generates your very own personalized firewall or script.
rcf is an ipchains-based firewall with extensive support for network services (IPSec, VTUN, NFS, SMB, Napster, Proxies, etc.), masquerading, port forwarding (including network games), and IP accounting.
rChains is a detailed, custom, ipchains ruleset that implements many features including, most noteably, per host bandwidth monitoring via MRTG and CGI log reports.
Regular Expression, Arbitrary Protocol, Opensource Filtering Firewall: an arbitrary protocol proxy. That is to say, the same proxy may be used to control any TCP/IP based protocol - the behavior of the proxy is fully specified by its configuration files
redir is a port redirector, used to forward incoming connections to somewhere else.
redWall Firewall is a bootable CD-ROM Firewall. It's goal is to provide a feature rich firewall solution, with the main goal, to provide a webinterface for all the logfiles generated.
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.
ROPE is a "match module" for Linux IpTables that allows packets to be matched using highly flexible rules, written in a simple purpose-designed scripting language. It was written initially to provide support for the next phase of the P2PWall project for controlling various styles of peer-to-peer application traffic, but is much broader than this in it's possible uses. See the Basics page for a tutorial-style overview.
rTables is a detailed, custom, iptables ruleset that is currently made up of a few simple bash scripts.
Sanewall is a firewall builder for Linux which uses an elegant language abstracted to just the right level. This makes it powerful as well as easy to use, audit, and understand. It allows you to create very readable configurations even for complex stateful firewalls.
The Seattle firewall is an ipchains based firewall that can be used on a dedicated masquerading firewall machine (including LRP), a multi-function masquerade gateway/server or on a standalone Linux system.
Securepoint Firewall Server SB
(commercial) Securepoint Firewall Server SB is a high-performance, commercial-grade application designed to offer full protection for network assets.
SekHost is an iptables control script with a very flexible configuration and packet prioritization features.
ShellTer is an iptables-based firewall. What sets it apart from the rest is that it has built-in SSH brute force protection. It is easy to configure and has an interactive CLI installer. Read more
Shoreline Firewall is an iptables based firewall that can be used on a dedicated firewall system, a multi-function masquerade gateway/server or on a standalone Linux system. Read more
Simple Firewall is an easy tool for administration users and access control using iptables for packet filtering.
SlackFire (SF) is an iptables script with a number of configuration files. SF is aimed to protect a (Slackware) Linux machine or a LAN with SF being used on the router/gateway with a stateful firewall.
SMCRoute is a command line tool to manipulate the multicast routes of the Linux kernel. It can be used as an alternative to dynamic multicast routers like 'mrouted' in situations where static multicast routes should be maintained and/or no proper IGMP signaling exists.
Sopeq is a stealh ingress and egress filtering firewall for IPTables with an easy to configure rules file. Sopeq can be used to configure even the slightest details of IPTables with just a minor change in the rules file.
SRFirewall is a simple, but powerful netfilter/iptables firewall script for Linux systems.
SunGazer Packetfilter is a small and simple tool to set up firewall rules. It works with iptables and is easy to use and configure.
The Doorman guards the door of a server, manipulating firewall rules to admit only recognized parties. Allows Silent Running - a server with all ports CLOSED. Linux-BSD-OSX server & client; C source & docs + Windows client binary. GPL.
theWall is a collection of PicoBSD configuration trees and prebuild binaries for various platforms that provides NAT and firewall services for a small network.
TuxGuardian is an application-based firewall that allows the implementation of access control policies in order to identify and control every application that tries to access the network.
Currently, UFW provides only a command-line interface (CLI) for user interaction--the ufw command.
UIF is used to generate optimized iptables packet filter rules, using a simple description file specified by the user.
Ufw stands for Uncomplicated Firewall, and is program for managing a netfilter firewall. It provides a command line interface and aims to be uncomplicated and easy to use.
Untangle's Firewall filters traffic based on IP address, protocol and ports and allows administrators to: designate which systems and services (http, ftp, etc.) are publicly available, create a DMZ and perform NAT (with Router), and run as a transparent bridge to complement existing hardware. Read more
vt-ng detects virus and worm like activity based on communication patterns. It can be used to detect infected hosts within your internal network and stop the spread of malware.
Vuurmuur is a powerful firewall manager built on top of iptables that works with Linux kernels 2.4 and 2.6. Read more
The goal of the WallFire project is to build a very general and modular firewalling application based on Netfilter or any kind of low-level framework.
Wfconvert is a firewalling tool which imports/translates rules from/to any supported firewalling language.
Wflogs is a firewall log analysis tool. It can be used to produce a log summary report in plain text, HTML and XML, or even to translate a log file into another firewall log format.
(commercial) Wolverine Firewall and VPN Server - Wolverine is Wolverine Firewall is a commercial grade firewall and VPN solution, designed for use by any size organization. Offering a stateful packet inspection, IPSEC and PPTP VPN services in a very small foot-print while requiring a minimal amount of hardware to operate, Wolverine offers very cost effective solution for network perimeter defense.
XFwall is a graphical firewall software for Linux aimed at corporate users. The software has been adopted by private and governmental companies in Brazil. XFwall can be used with client, servers, and (mainly) gateway machines.
Xtables2 is an effort to do gradual improvements and modernize the packet filter, with input from especially the user community itself.
YAFIG is a LAMP-based firewall rule generator that creates shell scripts for use with Linux netfilter/iptables.
Zorp is a new-generation proxy firewall suite to finetune proxy decisions (with its built in script language), fully analyze complex protocols (like SSH with several forwarded TCP connections), and utilize outband authentication techniques.