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| | Evolution of the Firewall Industry |
 | | Packet filters do not require client computers to be specifically configured; the packet filters do all of the work. | | | Packet filters cannot restrict what information is passed from internal computers to services on the firewall server. | | | Packet filters are generally faster than other firewall technologies because they perform fewer evaluations. |
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http://www.cisco.com/univercd/cc/td/doc/product/iaabu/centri4/user/scf4ch3.htm
(6515 words)
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| | GeodSoft How-To Harden OpenBSD Using Packet Filter |
| | Firewall software such as IP Filter and its 3.0 replacement, Packet Filter, has traditionally been used to create firewalls on computers with two or more network interfaces. | | | Depending on the OpenBSD version, Packet Filter or IP Filter can also be used as a more flexible and powerful replacement for TCP Wrappers protecting only the computer on which it runs. | | | Packet Filter has a how-to at http://www.inebriated.demon.nl/pf-howto/ Anyone doing an IP Filter firewall should read the "ipf HOWTO" available in several formats at http://www.obfuscation.org/ipf/. |
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http://www.geodsoft.com/howto/harden/OpenBSD/firewall.htm
(7343 words)
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| | Inside the Linux Packet Filter Linux Journal |
| | In that article I provided an overview of the functionality of the packet filter itself; this time, I delve into the depths of the kernel mechanisms that allow the filter to work and share some insights on Linux packet processing internals. | | | Packet reception is first dealt with at the network card's driver level, more precisely in the interrupt service routine. | | | IP header data is trimmed so that the packet is ready to be transferred to the layer 4 protocol. |
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http://www.linuxjournal.com/article.php?sid=4852
(3109 words)
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| | Ethereal Capture Filters |
| | This filter is designed to look at the standard offset into the tcp header (tcp[20]) and match the payload with your filter string. | | | Any of the preceeding filters can be designed with byte offset notation by locating its offset in the appropriate header. | | | Always keep a layout of the headers of interest handy when designing filters with byte offset notation (for example: ip,udp,tcp and icmp). |
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http://home.insight.rr.com/procana
(1337 words)
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| | bpf(4) - Berkeley Packet Filter |
| | Whenever a packet is received by an interface, all file descriptors listening on that interface apply their filter. | | | "i" in the packet, interpreted as a word (n=4), unsigned halfword (n=2), or unsigned byte (n=1). | | | The packet filter will support any link level protocol that has fixed length headers. |
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http://www.gsp.com/cgi-bin/man.cgi?section=4&topic=bpf
(1960 words)
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| | BSD Packet Filter |
| | Interpretation was chosen to make it possible to move packet filters from user space, with the associated context switches and kernel traps, into the kernel, saving that overhead. | | | With several sessions active at the same time, many filters that differ only minimally (in matching the destination port number for example), have to be installed. | | | Therefore, the claim that a stack-based virtual machine is not as suitable as a register-based virtual machine for modern CPUs is not substantiated. |
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http://www.cs.unm.edu/~riesen/prop/node40.html
(462 words)
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| | SINUS Firewall Page |
| | The SINUS Firewall is a TCP/IP packet filter for the Linux operating system. | | | Filtering of all header fields in the IP, TCP, UDP, ICMP, IGMP packets. | | | It is distributed under the GNU General Public Licence and comes with complete source code, as the Linux operating system does. |
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http://www.ifi.unizh.ch/ikm/SINUS/firewall
(336 words)
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| | Burning Void--Infrequently Asked Questions for Sysadmins: Packet Filter vs. Proxy Firewalls |
| | The problem is even greater with UDP; assuming the packet filter permits UDP DNS queries to port 53, the attacker may send UDP packets from port 53 to ports on machines behind the firewall. | | | Filters just look at the protocol level information in the packet. | | | The SPF is supposed to have built-in knowledge about TCP/IP's rules for data flow between the two hosts. |
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http://www.burningvoid.com/iaq/firewall-type.html
(1374 words)
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| | dynamic packet filter - a Whatis.com definition |
| | This kind of filter would allow an attacker to sneak information past the filter by making the packet look like a reply (which can be done by indicating "reply" in the packet header). | | | With a static packet filter, you would need to permanently allow in replies from all external addresses, assuming that users were free to visit any site on the Internet. | | | By tracking and matching requests and replies, a dynamic packet filter can screen for replies that don't match a request. |
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http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212023,00.html
(269 words)
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| | Feature: Porting The PF Stateful Packet Filter |
| | Packet filter rules assign packets to queues, which saves a separate evaluation of a classification ruleset, and the state engine in pf can use that state entries to assign connections to queues statefully. | | | Daniel demonstrates the power of this merge in his informative paper titled "Prioritizing empty TCP ACKs with pf and ALTQ", offering instructions on how to configure the packet filter to prevent an upload from affecting download throughput, with impressive results. | | | But with 3.3, you can already balance load to multiple uplinks or servers, like a redirection rule that forwards incoming HTTP requests to multiple local web servers, distributing the load according to various schemes (round-robin, source hash, etc.). |
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http://kerneltrap.org/node.php?id=627
(2636 words)
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| | ONLamp.com: OpenBSD PF Developer Interview |
| | What started as a project to safely parse pflogs for generating ASCII logs resulted in security extensions to bpf (berkeley packet filter which is used for capturing packets from the net and reading the pf logs) and privilege separation of pflogd, and tcpdump. | | | CB: I've used PF since 3.0 in an environment where I need to filter thousands of IP addresses individually, and that configuration was not handled very efficiently with early version of PF. | | | An attacker could look at a machine's responses to know it hasn't been rebooting since the last patch came out so it is probably still vulnerable. |
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http://www.onlamp.com/pub/a/bsd/2004/04/15/pf_developers.html
(2509 words)
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| | Packet Filtering |
| | Packet Filtering with iphlpapi.dll, Windows Developer's Journal, Ton Plooy, Windows Developers Journal, October, 2000, Volume 11, Number 10. | | | NDIS-hooking filter drivers intercept or "hook" selected functions exported by the NDIS wrapper. | | | For example, implementation of QOS could be done in a Winsock LSP. |
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http://www.ndis.com/papers/winpktfilter.htm
(1003 words)
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| | Detecting and Resolving Packet Filter Conflicts - Adiseshu, Suri, Parulkar (ResearchIndex) |
| | Packet classification is essential to routers supporting services such as Quality of Service (QoS), Virtual Private Networks (VPNs), and firewalls. | | | A filter conflict occurs when two or more filters overlap, creating an ambiguity in packet classification. | | | Survey Taxonomy of Packet Classification Techniques - Wucse- (2004) |
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http://citeseer.ist.psu.edu/hari00detecting.html
(499 words)
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| | 6 - Networking |
| | Unlike a router, packets transfer through the bridge "invisibly" -- logically, the two network segments appear to be one segment to nodes on either side of the bridge. | | | While it is possible to filter on both, you really need to understand this very well to do it right. | | | Other results could be had by filtering the other interface. |
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http://www.openbsd.org/faq/faq6.html
(7679 words)
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| | Kerio - internet security software from one of the market leaders. |
| | Anti Spam Filter, Router Software Windows Email Spam Filter. | | | Residing on each desktop computer, Kerio Personal Firewall allows advanced users or network administrators to create packet filter rules that block or limit traffic for specific ports, protocols, or IP addresses, adding a level of control and security found in sophisticated network firewalls. | | | Our solutions range from an anti spam filter via email server software, firewall software, intrusion detection software, linux webmail server up to PC router software. |
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http://www.kerio.com
(1210 words)
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| | Linux 2.4 Packet Filtering HOWTO: So What's A Packet Filter? |
| | A packet filter is a piece of software which looks at the header of packets as they pass through, and decides the fate of the entire packet. | | | Make sure you do something intelligent if one of the commands should fail (usually `exec /sbin/sulogin'). | | | 3.1 Why Would I Want to Packet Filter? |
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http://www.iptables.org/documentation/HOWTO/packet-filtering-HOWTO-3.html
(714 words)
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| | 8.1. Packet Filter Rules |
| | The protocol is specified by a designated number in the IP packet header. | | | More complex combinations of filtering rules can be defined thanks to these features. | | | These facts should be considered during packet filter definition. |
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http://www.kerio.com/manual/kpf/en/ch08s01.html
(1722 words)
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| | Packet Filter Software |
| | Network Sn software, web browsing software, http analyzer software, packet sniffer software, web monitor software, web sniffer software, http sniffer software, | | | An explorer-like interface displays the file details, including information such as version numbers, and can be both filtered and sorted by any attribute. | | | The displayed files can also be recursive, where files in sub-folders are also shown in the list. |
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http://www.cutedownloads.com/two/packet-filter.htm
(316 words)
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| | Linux 2.4 Packet Filtering HOWTO: Advice on Packet Filter Design |
| | Route verification is where a packet which comes from an unexpected interface is dropped: for example, if your internal network has addresses 10.1.1.0/24, and a packet with that source address comes in your external interface, it will be dropped. | | | Common wisdom in the computer security arena is to block everything, then open up holes as neccessary. | | | ppp0 -m limit -j LOG --log-prefix "Bad packet not from ppp0:" # iptables -A no-conns-from-ppp0 -j DROP # iptables -A INPUT -j no-conns-from-ppp0 # iptables -A FORWARD -j no-conns-from-ppp0 |
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http://www.kazoolug.org/presentations/20020129/packet/netfilter-11.html
(416 words)
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| | Daemon News '200207' : '"HOWTO: Transparent Packet Filtering with OpenBSD "' |
| | This example assumes your two network interfaces are named fxp0 and fxp1. | | | These methods will prove invaluable as you develop more complex rulesets and enable more sophisticated logging. | | | More information and ruleset examples can be found in the |
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http://ezine.daemonnews.org/200207/transpfobsd.html
(957 words)
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| | Microsoft Internet Security & Acceleration Server (ISA) 2000 - Apply an IP packet filter to a server |
| | In the console tree of ISA Management, click IP Packet Filters. | | | To open ISA Management, click Start, point to Programs, point to Microsoft ISA Server, and then click ISA Management. | | | Microsoft Internet Security and Acceleration Server (ISA) 2000 - Apply an IP packet filter to a server |
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http://www.microsoft.com/resources/documentation/isa/2000/enterprise/proddocs/en-us/isadocs/m_p_h_ipapplyserv.mspx
(148 words)
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| | IP Filter - TCP/IP Firewall/NAT Software |
| | the first 128 bytes of the packet (including headers) | | | provide packet header details to a user program for authentication | | | ipresend - reads in a data file of saved IP packets (ie snoop/tcpdump/etherfind output) and sends it back across the network. |
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http://coombs.anu.edu.au/~avalon/ip-filter.html
(754 words)
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| | freshmeat.net: Project details for fairly fast packet filter |
| | The fairly fast packet filter (FFPF) is an approach to network packet processing that adds many new features to existing filtering solutions like BPF. | | | By providing both a richer programming language and explicit extensibility, it is also considerably more flexible than existing approaches. | | | freshmeat.net: Project details for fairly fast packet filter |
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http://freshmeat.net/projects/ffpf
(205 words)
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| | How To Enable DHCP Client IP Packet Filter. |
| | Current project is to develop a practical how to manual for the ISA Server and Windows 2000 OS Server/Professional. | | | On Local Computer tab select the option that applies to you. | | | On Remote Computer tab select the option that applies to you. |
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http://www.isaserver.org/pages/article_p.asp?id=336
(110 words)
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| | Sys Admin > IPTables/NetFilter — Linux’s Next-Generation Stateful Packet Filter |
| | The IPTables/NetFilter application is considered to be the fourth generation of Linux packet filtering implementations. | | | One of the goals of NetFilter was to provide a single, dedicated packet filter/mangler infrastructure that users and developers could deploy as an add-on built around the Linux kernel. | | | Paul “Rusty” Russell and Michael Neuling made some significant modifications to the 2.2 Linux kernel, and Russell added the user tool ipchains for controlling filtering rules for this kernel. |
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http://www.samag.com/documents/s=1769/sam0112a/0112a.htm
(816 words)
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| | Network Packet Analyzer over Ethernet and WLAN |
| | Javvin Packet Analyzer is competitive in features and performance with other tools that are priced multiple times higher...simply try it. | | | Decodes packet headers for the often used TCP/IP protocols and applications | | | Order Network Packet Analyzer now and get a free copy of Javvin's Map of Communication Protocols. |
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http://www.javvin.com/packet.html
(950 words)
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| | Fairly Fast Packet Filter - overview |
| | The fairly fast packet filter (FFPF) is an approach to network packet processing that adds many new features to existing filtering solutions like BPF. | | | By providing both access to richer programming languages and explicit extensibility, it is also considerably more flexible than existing approaches. | | | FFPF is made possible with funding from the EU Scampi research initiative into network monitoring |
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http://ffpf.sourceforge.net
(269 words)
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| | IT Observer - Understanding OpenBSD's Packet Filter |
| | Packet Filter is the excellent firewall software made by the OpenBSD team. | | | The concept of "last matching rule wins" is critical to developing a PF ruleset. | | | Even if a packet matches a rule PF will continue evaluating as it may match another rule. |
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http://www.ebcvg.com/news.php?id=1942
(308 words)
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| | Sys Admin > v13, i03: Monitoring Net Traffic with OpenBSD's Packet Filter |
| | However, as I was setting up tighter security on my OpenBSD machine, I noticed that the Packet Filtering firewall software could give me statistics on named rules. | | | This would be easy to solve if I controlled the upstream router for the box, but I don't. | | | In the filtering section of my /etc/pf.conf file, the last dozen rules look like: |
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http://www.samag.com/documents/s=9053/sam0403j/0403j.htm
(755 words)
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| | pfflowd - NetFlow probe for OpenBSD pf packet filter |
| | OpenBSD's PF stateful packet filter will count bytes and packets for flows it tracks statefully. | | | The pfsync interface has been in constant development since it was introduced into OpenBSD. | | | Reusing the kernel's packet filtering system has a number of advantages. |
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http://www.mindrot.org/pfflowd.html
(693 words)
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| | Securing Small Networks with OpenBSD |
| | Since its introduction in OpenBSD 3.0, it has become an advanced tool for networking and security. | | | Since its introduction in OpenBSD 3.0, it's become an advanced tool for networking and security. | | | OpenBSD switched from using IPFilter as its default firewall to PF, or Packet Filter, as the new default. |
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http://www.onlamp.com/pub/ct/58
(561 words)
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| | filtergen, a packet filter compiler |
| | "filtergen" (the package formerly known as "filter") is a packet filter generator. | | | You can discuss both packages on the fk mailing list. | | | It compiles a fairly high-level description language into iptables, ipchains or ipfilter rules (and has bits of support for Cisco IOS access-lists). |
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http://hairy.beasts.org/filter
(189 words)
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| | OpenBSD firewall using pf |
| | As opposed to queueing disciplines, traffic conditioners handle incoming packets at an input interface. | | | All the machines on the private network should be configured to use the address of the private interface of the OpenBSD box as the default gateway. | | | One noticable difference is OpenBSD pf doesn't support IP Filter ``keep frags'' syntax. |
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http://www.muine.org/~hoang/openpf.html
(1761 words)
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| | PACKET FILTER TO WATCH RIP PACKETS |
| | This is on of the protocols the PortMaster uses to learn dynamic routing information. | | | RIP is a routing protocol that uses udp/520 to transmit routing information between hosts. | | | A packet filter to watch the RIP updates can be useful in debugging routing problems. |
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http://www.portmasters.com/tech/technotes/300/303006.html
(66 words)
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| | Chapter 8. Advanced Packet Filter |
| | Rules for packet filter can be defined as follows: | | | The packet filter allows for definition of advanced rules for specific network communication. | | | Connection Alert (unknown traffic detection)); if the Create an advanced filter rule option is checked, a packet filter rule will be created instead of a standard rule. |
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http://www.kerio.com/manual/kpf/en/ch08.html
(159 words)
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| | Application Layer Packet Classifier for Linux |
| | It complements existing classifiers that match on IP address, port numbers and so on. | | | Netfilter that identifies packets based on application layer data. | | | To download, see our Sourceforge project page (but read the HOWTO first). |
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http://l7-filter.sourceforge.net
(377 words)
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| | Remote pf (packet filter) control daemon |
| | Basic installation instructions can be found in the README file. | | | I might continue to work on this later. | | | Project has been put on hold, since to many changes are happening in the pf(4) code for me to keep up. |
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http://www.insecure.dk/rpfcd
(190 words)
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| | Klexus Search Engine: packet filter (10) |
| | ] PF: The OpenBSD Packet Filter Table of Contents Configuration Lists and Macros Tables Options Scrub Queueing Network Addres... | | | LinkFerret Network Monitor provides true promiscuous 802.11b monitoring via the use of custom drivers developed for Cisco and... | | | pfstat pfstat is a small utility that collects packet filter statistics and produces graphs like those shown below (ADSL 512/... |
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http://www.klexus.com/packet_filter
(177 words)
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| | March 2004 - Proxy vs. Packet Filter ... |
| | The technology is so commonplace that packet filtering is built into $99 SOHO devices. | | | Proxy-based firewalls can easily do all kinds of application-layer validity checking, antivirus scanning and content filtering, as well as granular access control, because they are truly aware of the application data flow. | | | Proxy firewall vendors, sensitive to their performance constraints, have added packet filtering where appropriate. |
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http://infosecuritymag.techtarget.com/ss/0,295796,sid6_iss346_art662,00.html
(468 words)
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| | 602LAN SUITE - Advanced software firewall security with packet filter |
| | Packet filtering on the device level provides the best performance and security. | | | The firewall acts as a packet filter between two or more network devices (e.g. | | | Since the firewall is integrated, no other application or hardware is required to secure your network! |
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http://www.software602.com/products/ls/firewall.html
(268 words)
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| |
| | Definition: packet filter |
| | packet filter: A type of firewall in which each packet is examined and either allowed to pass through or is rejected, based on local security policy. |
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http://www.atis.org/tg2k/_packet_filter.html
(63 words)
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| | DPF: fast, flexible packet demultiplexing |
| | We present a new packet-filter system, DPF (Dynamic Packet Filter), that provides both the traditional flexibility of packet filters~\cite{mogul:packet-filter} and the speed of hand-crafted demultiplexing routines~\cite{clark:analysis}. | | | DPF filters run 10--50 times faster than the fastest packet-filter numbers reported in the literature. | | | DPF's performance is either equivalent to or, when it can exploit runtime information, superior to hand-coded demultiplexors. |
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http://pdos.csail.mit.edu/~engler/dpf.html
(141 words)
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| |
| | The Tech Encyclopedia |
| | Most viewed terms: contract management, manufacturing software, network security, SSL, encrypted email, spam filter, help desk software, web conferencing, security consulting, CISA | | | If you would like to submit an entry, please reply to the email address below. | | | If you have comments or additions that you wish to make, please |
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http://www.Tech-Encyclopedia.com
(106 words)
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| | benzedrine.cx - Mailing list |
| | If delivery to your subscribed address fails with a permanent error (like 'user unknown') or temporarily for several days (DNS problems, mailbox over quota) or otherwise generates repeated bounces (mail forwarding problems), it will get unsubscribed automatically. | | | Messages appearing to be spam are bounced and need to be manually approved. | | | In case you managed to upset the spam filter with your distinguished choice of words (as can happen in the heat of a decent flame war ;) you can resend the message with the word spamassassinexception anywhere in the body, and it shall pass. |
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http://www.benzedrine.cx/mailinglist.html
(317 words)
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