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Topic: Ingress filtering

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	RFC 3704 (rfc3704) - Ingress Filtering for Multihomed Networks
		While this is by no means the only way to implement an ingress filter, it is the one proposed by RFC 2827 [1], and in some sense the most deterministic one.
		However, Ingress Access Lists are typically maintained manually; for example, forgetting to have the list updated at the ISPs if the set of prefixes changes (e.g., as a result of multihoming) might lead to discarding the packets if they do not pass the ingress filter.
		However, unless ingress filtering (or at least, a limited subset of it) has been deployed at every border (towards the customers, peers and upstreams) -- blocking the use of your own addresses as source addresses -- the attackers may be able to circumvent the protections of the infrastructure gear.
	www.faqs.org /rfcs/rfc3704.html (4147 words)

	Encyclopedia: Ingress filtering (Site not responding. Last check: )
		In computer networking, the term Ingress filtering is the process of filtering out packets originating from outside the network, but which have a source address indicating origination from inside the network.
		If ingress filtering is used in an environment where DHCP or BOOTP is used, the network administrator would be well advised to ensure that packets with a source address of 0.0.0.0 and a destination of 255.255.255.255 are allowed to reach the relay agent in routers when appropriate.
		However, unless ingress filtering (or at least, a limited subset of it) has been deployed at every border (towards the customers, peers and upstreams) -- blocking the use of your own addresses as source addresses -- the attackers may be able to circumvent the protections of the infrastructure gear.
	www.nationmaster.com /encyclopedia/Ingress-filtering (526 words)

	[No title] (Site not responding. Last check: )
		The ingress is characterized by a number of relatively narrowband signals 102 of higher amplitude and wideband ingress 104 that is usually lower in amplitude.
		The ingress power that cannot be filtered according to the model will be summed over the bandwidth of the channel at 312 and compared to the anticipated signal power to arrive at a modeled signal to noise ratio of the channel 208 for channel quality assessment.
		The cable modem termination system of claim 22 wherein the spectrum analyzer measures the ingress of a channel that is inactive and the ingress cancellation filter operates on an active channel and is borrowed during periods of inactivity of the active channel for filtering of the inactive channel.
	www.wipo.int /cgi-pct/guest/getbykey5?KEY=03/93936.031113&ELEMENT_SET=DECL (2104 words)

	4th USENIX Symposium on Internet Technologies and Systems — Technical Paper
		Ingress filtering is increasingly deployed at the edge of the network, but its deployment is limited by router resources and operator resources.
		However, ingress filtering is most effective at the edge; deployment in the core, even if it becomes technically feasible, is not completely effective [20].
		Ingress filtering may reduce the number of hosts with this capability, but is unlikely to eliminate all of them.
	www.usenix.org /events/usits03/tech/full_papers/andersen/andersen_html (7750 words)

	Cs3 - Changing IP to Eliminate Source Forgery
		Ingress filtering, the much recommended but little used partial solution to source forgery, is still beneficial in the presence of PEIP.
		Source: forged source address (allowed by a router with ingress filtering misconfigured; failure to delete paths from the packets where this is required is regarded as worse than misconfigured, but actually attacking) Source forgery without use of an intermediary to reply to the forged source address is ignored since this seems comparatively trivial.
		If efforts to enforce ingress filtering meet with success, this sort of attack will become very difficult to execute and will be effectively limited to a small number of slaves.
	www.cs3-inc.com /sf.html (5232 words)

	RFC 2827 (rfc2827) - Network Ingress Filtering: Defeating Denial of Servic
		An additional benefit of implementing this type of filtering is that it enables the originator to be easily traced to it's true source, since the attacker would have to use a valid, and legitimately reachable, source address.
		Ingress filtering will take time to be implemented pervasively and be fully effective, but the extensions to the operating systems can be implemented quickly.
		If ingress filtering is used in an environment where DHCP or BOOTP is used, the network administrator would be well advised to ensure that packets with a source address of 0.0.0.0 and a destination of 255.255.255.255 are allowed to reach the relay agent in routers when appropriate.
	www.faqs.org /rfcs/rfc2827.html (2262 words)

	[No title] (Site not responding. Last check: )
		ingress filtering at the MR is the only solution to this.
		But the problem is that the attacker can launch this attack from outside, too if the ingress filtering at the access router of the attacker is not activated.
		The Mobile Router has to perform ingress filtering on packets received from the Mobile Network to ensure that nodes in the Mobile Network do not use the bi-directional tunnel to launch IP spoofing attacks.
	people.nokia.net /vijayd/nemo/issue23.txt (2977 words)

	Wireless Net DesignLine \| How to engineer VoIP on an enterprise WLAN (Site not responding. Last check: )
		More specifically with ingress filtering, the intelligent switch tries to identify the content of the traffic and determine the type of application that is being sent by looking at the port numbers in the TCP/UDP header.
		In relation to priority scheduling, ingress filtering allows the switch to determine if the packet is a voice application or a data application and assign priority accordingly (i.e., higher priority for voice packets and lower priority for data packets).
		Ingress filtering, egress scheduling and rate policing are all requirements for effective traffic engineering in current generation intelligent switching.
	www.wirelessnetdesignline.com /howto/171204182 (2851 words)

	CERT Advisory CA-2001-23 Continued Threat of the "Code Red" Worm
		Ingress filtering manages the flow of traffic as it enters a network under your administrative control.
		Thus, ingress filtering should be performed at the border to prohibit externally initiated inbound connections to non-authortized services.
		With "Code Red," ingress filtering will prevent instances of the worm outside of your network from infecting machines in the local network that are not explicitly authorized to provide public web services.
	www.cert.org /advisories/CA-2001-23.html (1457 words)

	RIPE \| Document Store \| ripe-379 - RIPE "IP Anti-Spoofing" Task Force
		This demonstrates that ingress filtering is definitely not deployed sufficiently.
		Also, there is a widely held belief that ingress filtering only helps when it is universally deployed.
		At RIPE 52 in Istanbul, RIPE established a task force that promotes deployment of ingress filtering at the network edge by raising awareness and provide indirect incentives for deployment.
	www.ripe.net /ripe/docs/ripe-379.html (425 words)

	[No title]
		Becuase of ingress filters, many unidirectional paths may result (packets are dropped when flowing in one direction).
		There should not be problems with the ingress filters, as we always use the source address associated to the given interface when sending packets out.
		However, you still may have problem with ingress filters because each address has been assigned by a different ISP, implying that if ingress filters are in place, each isp will only route those packets that contain the prefix delegated by the particular isp in the source address of the packet.
	www.vpnc.org /ietf-mobike/issue56.txt (1849 words)

	[No title]
		Its presence informs the router that the ingress filtering should be performed on the address in the CAO option rather than on the packet source address.
		The MN needs to set a flag, the filter flag (F), in the CAO to indicate whether or not the CAO or the source address is to be used for ingress filtering.
		If the filter flag is set then the ingress filtering is on the contents of the CAO whilst if it is not set then the ingress filtering is on the source address.
	www.join.uni-muenster.de /drafts/draft-oneill-mipv6-cao-00.txt (6683 words)

	draves-ipngwg-ingress-filtering-00.txt (Site not responding. Last check: )
		IPng Working Group Richard Draves Internet Draft Microsoft Research Document: draft-draves-ipngwg-ingress-filtering-00.txt May 18, 2001 Ingress Filtering, Site Multihoming, and Source Address Selection Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026 [1].
		If the ISP deploys source- address-based ingress filtering, the host will be unable to communicate with the destination.
		Conceivably, the prefix policy configuration could be automatically determined by the intra-site routers, since they have knowledge of Draves Expires December 2001 2 draft-draves-ipngwg-ingress-filtering-00 May 18, 2001 the routing, and distributed to the hosts via a new Router Advertisement option.
	bgp.potaroo.net /ietf/idref/draft-draves-ipngwg-ingress-filtering (1191 words)

	RFC2827 (Site not responding. Last check: )
		RFC 2827 Network Ingress Filtering May 2000 In response to this threat, most operating system vendors have modified their software to allow the targeted servers to sustain attacks with very high connection attempt rates.
		RFC 2827 Network Ingress Filtering May 2000 Mobile IP, as defined in [6], is specifically affected by ingress traffic filtering.
		RFC 2827 Network Ingress Filtering May 2000 The filtering could also, in practice, block a disgruntled employee from anonymous attacks.
	rfc.net /rfc2827.html (2316 words)

	RE: Source addresses, DDoS prevention and ingress filtering (Site not responding. Last check: )
		Right now the topological assumption is the norm and this is enforced with the fact that ingress filtering may or may not be on at any given point in the network.
		IMO, the fact that the filtering may or may not be on at any part of an IPv4 network is understandable due to the existing deployed base of routing products.
		Mandating source filtering for topological correctness on the first hop is a strawman proposal.
	www.research.att.com /lists/ietf-itrace/2001/03/msg00034.html (1538 words)

	MISSING TITLE
		Filtering of this nature has the potential to break some types of "special" services.
		Ingress traffic filtering at the periphery of Internet connected networks will reduce the effectiveness of source address spoofing denial of service attacks.
		The primary intent of this document is to inherently increase security practices and awareness for the Internet community as a whole; as more Internet Providers and corporate network administrators implement ingress filtering, the opportunity for an attacker to use forged source addresses as an attack methodology will significantly lessen.
	xml.resource.org /public/rfc/xml/rfc2267.xml (2080 words)

	[saag] Home Address Option in MIPv6 (Site not responding. Last check: )
		I suspect that it also depends on whether one views ingress filtering as an architecturally sensible strategy or a kludge to work around hosts that take action based on the source address of packets without any means of authentication.
		If one accepts ingress filtering as a reasonable strategy, then it seems that the Home Address option does make these attacks easier if the Home Address carried in the option is used for access control checks.
		Egress filtering has a different motivation, which is for an organization to avoid being a source of forged packets.
	bs.mit.edu /pipermail/saag/2001q4/000278.html (479 words)

	RFC 2267 - Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing. P. ...
		RFC 2267 Network Ingress Filtering January 1998 Similar attacks have been attempted using UDP and ICMP flooding.
		RFC 2267 Network Ingress Filtering January 1998 As mentioned previously, while ingress traffic filtering drastically reduces the success of source address spoofing, it does not preclude an attacker using a forged source address of another host within the permitted prefix filter range.
		RFC 2267 Network Ingress Filtering January 1998 when the source is more likely to be "valid." By reducing the number and frequency of attacks in the Internet as a whole, there will be more resources for tracking the attacks which ultimately do occur.
	rfc.sunsite.dk /rfc/rfc2267.html (2364 words)

	Ingress Filtering (Site not responding. Last check: )
		This means that filters will be installed to prevent traffic sourced from customer networks not registered for routing with AAPT from entering the AAPT network and will thus prevent this traffic from entering the networks of our peers and providers via AAPT.
		Once the ingress filters are deployed packets sourced from networks not registered with AAPT will be rejected.
		These filters will allow AAPT to ensure that customers are only able to inject traffic into the AAPT network which is identifiable back to the customer and thus allow us to readily identify the source of any "denial-of-service" attacks being initiated through a customer link and improving the overall network integrity.
	info.connect.com.au /docs/permconnections/ingress.html (475 words)

	Source addresses, DDoS prevention and ingress filtering (Site not responding. Last check: )
		One point that has came up several times, in various forms, in the DDoS discussion is the idea of mandating some sort of source address filtering, ingress filter, PRF of whatever it is called.
		First, those that believe in ingress filtering would perhaps be happy with the recorded packet path information.
		Second, those not believing in ingress filtering would be happy, too, since packets would not have to be dropped.
	www.research.att.com:9000 /lists/ietf-itrace/2001/03/msg00033.html (1199 words)

	Egress filtering (Site not responding. Last check: )
		If you've been around routers and firewalls for any amount of time, you're probably familiar with the concept of ingress filtering -- the application of a firewall rulebase to inbound traffic.
		Ingress filtering allows you to control the traffic that enters your network and restrict activity to legitimate purposes.
		As with any security control, exceptions to the standard egress filtering policy may be necessary depending upon your organization's unique needs.
	searchsecurity.techtarget.com /tip/1,289483,sid14_gci883409,00.html (582 words)

	[No title]
		Adding such a filter would then result in a denial of service to Ferguson & Senie Best Current Practice [Page 3] RFC 2827 Network Ingress Filtering May 2000 legitimate, non-hostile end-systems.
		Ferguson & Senie Best Current Practice [Page 4] RFC 2827 Network Ingress Filtering May 2000 In response to this threat, most operating system vendors have modified their software to allow the targeted servers to sustain attacks with very high connection attempt rates.
		Ferguson & Senie Best Current Practice [Page 6] RFC 2827 Network Ingress Filtering May 2000 Mobile IP, as defined in [6], is specifically affected by ingress traffic filtering.
	www.ietf.org /rfc/rfc2827.txt (2310 words)

	ingress filtering
		The result of course is that spammers and other bad guys can try to attack your systems with forged source IP addresses.
		MCI does not currently source filter address space at it's ingress points.
		Addresses sourced from non-routable or invalid addresses are not blocked or filtered.
	www.merit.edu /mail.archives/nanog/1998-05/msg00722.html (177 words)

	Web Security With Ingress Filtering - igvita.com
		Ingress vs. Egress data integrity policy debate is a long standing one, so let me try to sway you to the ingress side.
		Blacklists, as their name implies, attempt to remove elements which are known to cause problems: script, onclick, style, etc. However, this is a poor strategy because it amounts to a catch up game - you’re never sure that you caught every malicious element out there.
		Reasons 1 and 3 for ingress filtering: (1) you input once, but output many times (it’s efficient); (3) output directly from the database, means simpler code and less worries.
	www.igvita.com /blog/2007/04/27/web-security-with-ingress-filtering (1827 words)

	[No title]
		Network Working Group P. Ferguson Request for Comments: 2267 Cisco Systems, Inc. Category: Informational D. Senie BlazeNet, Inc. January 1998 Network Ingress Filtering: Defeating Denial of Service Attacks which employ IP Source Address Spoofing Status of this Memo This memo provides information for the Internet community.
		In other words, the ingress filter on "router 2" above would check: IF packet's source address from within 9.0.0.0/8 THEN forward as appropriate IF packet's source address is anything else THEN deny packet Network administrators should log information on packets which are dropped.
		Ferguson & Senie Informational [Page 6] RFC 2267 Network Ingress Filtering January 1998 As mentioned previously, while ingress traffic filtering drastically reduces the success of source address spoofing, it does not preclude an attacker using a forged source address of another host within the permitted prefix filter range.
	www.isi.edu /in-notes/rfc2267.txt (2261 words)

	CERT Advisory CA-2003-04 MS-SQL Server Worm
		Thus, ingress filtering should be performed at the border to prohibit externally initiated inbound traffic to non-authorized services.
		In the case of this worm, employing ingress and egress filtering can help prevent compromised systems on your network from attacking systems elsewhere.
		Blocking UDP datagrams with both source or destination ports 1434 from entering or leaving your network reduces the risk of external infected systems communicating with infected hosts inside your network.
	www.cert.org /advisories/CA-2003-04.html (900 words)

	CERT Advisory CA-2002-03 Multiple Vulnerabilities in Many Implementations of the Simple Network Management Protocol ...
		As a temporary measure, it may be possible to limit the scope of these vulnerabilities by blocking access to SNMP services at the network perimeter.
		For SNMP, ingress filtering of the following ports can prevent attackers outside of your network from impacting vulnerable devices in the local network that are not explicitly authorized to provide public SNMP services.
		However, it may have detrimental effects on network performance due to the increased load imposed by the filtering, so careful consideration is required before implementation.
	www.cert.org /advisories/CA-2002-03.html (12010 words)

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