Routing Area WG P. Savola
Internet-Draft CSC/FUNET
Intended status: Informational January 16, 2007
Expires: July 20, 2007
Backbone Infrastructure Attacks and Protections
draft-savola-rtgwg-backbone-attacks-03.txt
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Abstract
A number of countermeasures for attacks against service provider
backbone network infrastructure have been specified or proposed, each
of them usually targeting a subset of the problem space. There has
never been a more generic analysis of the actual problems, and which
countermeasures are even necessary (and where). This document tries
to provide that higher-level view.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Threat Model . . . . . . . . . . . . . . . . . . . . . . . 4
2. Attack Vectors . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Lower-layer Attacks . . . . . . . . . . . . . . . . . . . 5
2.2. Generic DoS on the Router . . . . . . . . . . . . . . . . 5
2.3. Generic DoS on a Link . . . . . . . . . . . . . . . . . . 6
2.4. Cryptographic Exhaustion Attacks . . . . . . . . . . . . . 6
2.5. Unauthorized Neighbor or Routing Attacks . . . . . . . . . 6
2.6. TCP RST Attacks . . . . . . . . . . . . . . . . . . . . . 7
2.7. ICMP Attacks . . . . . . . . . . . . . . . . . . . . . . . 7
3. Typical Countermeasures . . . . . . . . . . . . . . . . . . . 7
3.1. Filtering Addresses in Packets . . . . . . . . . . . . . . 7
3.2. Filtering Addresses in Routing Updates . . . . . . . . . . 8
3.3. GTSM . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.4. TCP-MD5 and Other Custom Authentication . . . . . . . . . 9
3.5. IPsec and IKE . . . . . . . . . . . . . . . . . . . . . . 9
4. Protocol Analysis . . . . . . . . . . . . . . . . . . . . . . 9
4.1. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. BFD . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4. BGP . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.5. Multicast Protocols (PIM, MSDP) . . . . . . . . . . . . . 11
5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . . 14
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . . . . . . . 16
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1. Introduction
A number of countermeasures for attacks against service provider
backbone network infrastructure have been specified or proposed, each
of them usually targeting a subset of the problem space. There has
never been a more generic analysis of the actual problems, and which
countermeasures are even necessary (and where). This document tries
to provide that higher-level view.
The scope of this document are backbone infrastructures and the
critical protocols that are required to function for legitimate
traffic to be correctly forwarded through the network. As such,
other important services or applications required by infrastructure
elements such as RADIUS, NTP, remote access, syslog, SNMP, and DNS
are out of scope. All such components should be adequately protected
through appropriate measures, the most important of which are proper
address and route filtering and restricting authorized access.
Additionally, the network might run additional routing protocols that
are not described in this memo, such as (G)MPLS, RSVP-TE or LDP.
1.1. Abbreviations
We exclude the common abbreviations such as TCP, ICMP and DNS.
BGP Border Gateway Protocol
BFD Bidirectional Forwarding Detection
DoS Denial of Service
DSCP DiffServ Code Point
GTSM Generalized TTL Security Mechanism
IGP Interior Gateway Protocol
IKE Internet Key Exchange
IRR Internet Routing Registry
IS-IS Integrated System - Integrated System (routing protocol)
LDP Label Distribution Protocol
(G)MPLS (Generalized) Multi-Protocol Label Switching
MSDP Multicast Source Discovery Protocol
NTP Network Time Protocol
OSPF Open Shortest Path First
PIM Protocol Independent Multicast
RADIUS Remote Authentication Dial-In User Service
RSVP-TE Resource Reservation Protocol - Traffic Engineering
SNMP Simple Network Management Protocol
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1.2. Assumptions
This document assumes that the service provider is doing at least
some form of address filtering at its border devices, i.e., by
ensuring that only the infrastructure nodes can use infrastructure
source IP addresses to talk to the other nodes in the infrastructure.
So, for example, if a router sees an IP packet coming from a source
address assigned to another router in the backbone, it can be sure
the packet has been originated inside the backbone (assuming the
physical security or nodes in the backbone have not been subverted).
NOTE: many SP networks do not fulfill this assumption, often due to
(1) legacy equipment which is not capable of line-rate filtering,
and/or (2) very large network with hundreds or even thousands of
devices is considered just too big to guard at the borders (and
sometimes can't be broken down to several smaller ones). Analysis of
this document does not and will not intend to cover these networks as
the problem space is substantially different and other approaches are
warranted. For example, [I-D.zinin-rtg-dos] suggested an alternative
and provides good analysis; cryptographic protection of all the
control traffic may be an option if "all bets are off".
This requirement can be satisfied by applying ingress filtering at
all the ISP borders [RFC2827][RFC3704] for example, using feasible
path strict uRPF towards customers and ingress access lists towards
peers and upstreams. However, just filtering the infrastructure IP
addresses used as source addresses from the outside is also
sufficient. Some may even implement this by blocking access to the
infrastructure destination addresses at the border, but this document
doesn't describe this approach as that has a number of other issues.
Current operational practices are described in
[I-D.ietf-opsec-current-practices]. Various filtering capabilities
have been discussed at more length in [I-D.ietf-opsec-filter-caps].
1.3. Threat Model
In the context of this document, threats are assumed to come from
external sources, either from customers or other networks. The
typical attacks are either meant to cause some form of denial of
service or simply cause collateral damage, such as:
o DoS attacks directed at infrastructure (e.g., TCP RSTs, ICMP
attacks),
o Collateral damage from DoS and other attacks directed at someone
else but causing harm to infrastructure or service (e.g., too much
traffic exceeds forwarding or control processor capacity), or
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o Hijacking attacks (e.g., unauthorized routing advertisement,
access control attempt with a spoofed address).
Other possible attack vectors but which are considered out of scope
include:
o ISP's systems being compromised through unauthorized access,
system vulnerability, etc.,
o Inside attacks (e.g., compromised personnel),
o Lower-layer attacks as described in Section 2.1.
While not perfect solutions, these can all be mitigated to some
degree by controls and automatic configuration audits. As such the
first order priority problems typically come from external sources.
2. Attack Vectors
This Section describes the most obvious attack vectors. Many of
these are also described in [RFC4732].
2.1. Lower-layer Attacks
If an attacker has access to a (physical) link, it can obviously
cause downtime for the link. In many cases the downtime is not a
critical threat, as it can be quickly noticed, traffic rerouted, and
the problem fixed. Some ISPs are more concerned about other forms of
attacks: insertion of eavesdropping or man-in-the-middle devices.
Fortunately, installing such would require downtime, and insertion
could be noticeable, e.g., as an unscheduled issue gets fixed on its
own.
However, a lower-layer attack is not specific to routing protocols.
An attacker could just violate integrity or confidentiality of
regular packets, instead of tampering with routing. As such, if a
lower-layer attack is deemed a concern, full protection for all the
traffic should be provided and therefore this threat is not addressed
in this document.
2.2. Generic DoS on the Router
A typical attack is to overload a router using various techniques,
e.g., by sending traffic exceeding the router's forwarding capacity,
sending special transit packets that go through a "slow-path"
processing (such functions may also come with problems of their own
[BLOCKED]), or by sending some packets directed at the router itself
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(e.g., to exceed the input queue for CPU processing).
Many of these techniques can be mitigated using implementation-
specific rate-limiting mechanisms, so they are not addressed further
in this memo. However, protocol designers should be advised to avoid
any designs that require noticing and processing any special packets
from the transit traffic (e.g., messages marked with router alert
option).
2.3. Generic DoS on a Link
Overloading the capacity of a link is often more difficult to prevent
than a router DoS. Traffic is typically not automatically rerouted
and even if it was, doing so could make the issue worse unless there
is ample spare capacity.
Mitigation methods include monitoring the usage status of links,
prioritizing or deprioritizing certain kinds of traffic using DSCPs,
or devising some form of rate-limiters.
2.4. Cryptographic Exhaustion Attacks
A special form of DoS are attacks which target a protocol that uses
cryptographic mechanisms, for example TCP-MD5 or IPsec. The attacker
sends valid protocol messages with cryptographic signatures or other
properties to the router, which is forced to perform cryptographic
validation of the message. If the cryptographic operations are
computationally expensive, the attack might succeed easier than with
other generic DoS mechanisms. Cryptographic protocols employing
primitives such as stateless cookies, puzzles or return routability
are typically more resistant to this kind of attacks.
Some implementation-specific mitigation techniques (rate-limiting
etc.) have been deployed. Protocol design should take these attacks
into account.
2.5. Unauthorized Neighbor or Routing Attacks
Unauthorized nodes can obtain a routing protocol adjacency on links
where an IGP has been enabled by misconfiguration, or where
authentication is not used. This may result in many different kinds
of attacks, for example traffic redirection [RFC4593].
At least in theory, while it may not be possible to establish an
adjacency from outside the link, it may be possible to inject packets
as if the adjacency had been established (e.g., OSPF in Section 4.1.2
of [I-D.ietf-rpsec-ospf-vuln]).
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Protocols such as BGP and MSDP that process routing information from
untrusted, external sources may also be attacked, for example by an
unauthorized advertisement of a prefix.
Special care needs to be made to ensure that unauthorized neighbors
are prevented (e.g., by regular configuration audits and OSPF
protocol filtering at borders). On the other hand, routing attack
threats from valid neighbors can be slightly mitigated via
appropriate route filtering.
2.6. TCP RST Attacks
TCP sessions can be closed by attackers that can send a TCP RST
packet with guessed spoofed endpoint identifiers and a sufficiently
close sequence number. The attacks and defenses have been described
at length in [I-D.ietf-tcpm-tcp-antispoof]. One particular approach
is modifying the TCP state machine [I-D.ietf-tcpm-tcpsecure].
2.7. ICMP Attacks
A slightly newer attack is employing ICMP by sending an ICMP type
that indicates a hard error condition. ICMP errors must be
propagated to the upper layer, and most applications heed the errors
as they should by closing a connection or session. ICMP attacks and
defenses against TCP have been extensively described in
[I-D.ietf-tcpm-icmp-attacks]. Most TCP stacks have since then been
fixed [CVE].
It is also possible to execute ICMP attacks against other protocols
such as UDP or IPsec, but the impact and whether/how these protocols
demultiplex received errors have not been extensively studied. IPsec
is protected by ICMP attacks through a number of assumptions (e.g.,
that only ICMP errors from the end-point are accepted) or manual
configuration.
3. Typical Countermeasures
This Section describes some of the most common countermeasures
applied today. This just introduces the techniques; the afforded
protection is analyzed in Section 4 in the context of each protocol.
3.1. Filtering Addresses in Packets
As described in the first section, this document assumes that the
internal infrastructure is secure from spoofed messages that purport
to come from inside the infrastructure. More fine-grained, router-
specific filters are sometimes deployed as well.
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It is possible to hide the infrastructure by using private or non-
advertised addressing, but this has numerous drawbacks such as
breaking address filtering and traceroute, not protecting from the
ISP's customers that use a default route, etc. so this document
doesn't recommend doing so.
In addition, it may also make sense to ensure that egress packets
have the ISP's own source addresses and/or that ingress packets
arrive with either multicast/broadcast or ISP's own destination
addresses. These ensure that in case your own filtering fails, no
bad traffic leaks out and prevent certain classes of abuse from peers
(e.g., stealing transit by static routing).
3.2. Filtering Addresses in Routing Updates
Similar principles as used in address filtering can be used to
mitigate routing attacks. Specifically, reject any equal or more
specific incoming routing advertisements to the ISP's address space
unless explicitly authorized. Further, monitor the filtered prefixes
and use public services (such as RIPE's MyASN [MYASN]) to monitor the
correctness of advertisements globally.
As with address filtering, such routing advertisements might still be
processed by other networks, but at least these steps prevent
hijacking inside the ISP's own network and allow monitoring of most
unauthorized attempts.
It may also make sense to filter out in a similar fashion the
advertisements or more specifics of IX peering blocks where the ISP
connects to. These could be advertised by an attacker to mess up
forwarding next-hops.
In addition, especially in regions where the operational practice is
to keep Internet Routing Registry (IRR) in sync, it may be possible
to restrict the prefixes accepted from a peer or a customer to an
automatically generated list. In any case, many operators define a
maximum prefix limit per peer (which typically resets the session if
exceeded) to prevent misconfiguration (e.g., unintentional
deaggregation) or overload attacks.
3.3. GTSM
GTSM [I-D.ietf-rtgwg-rfc3682bis] is a technique where the sender of a
packet sets the TTL/Hop Count to 255 and the receiver verifies it's
still 255 (or some other preconfigured value). GTSM can be used to
protect from off-link attacks (especially spoofing). This applies
when GTSM-enabled control traffic is inside a single link: any
packets coming from outside the link can summarily be discarded as
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they have a TTL/Hop Count smaller than 255.
The open issue at the moment is how GTSM handles TCP RSTs. I.e.,
should it require that RSTs for a GTSM-enabled session should be sent
with TTL=255 and verified to come with TTL=255 (or a configured
value)? Some implementations already send out all packets with
TTL=255, but receipt verification is not performed. Is there a
sensible transition plan or need to make a change if any? Note that
this has only limited impact on GTSM's security as other TCP RST
mitigation techniques still apply.
NOTE IN DRAFT: the following paragraph should be removed in a future
revision, to be placed to the GTSMbis draft.
We suggest that the GTSM spec is amended so that TCP RSTs relating to
a GTSM-enabled protocol port MUST be sent with TTL=255. The
recipient's behaviour SHOULD be configurable, and it is RECOMMENDED
that the default be to discard messages where TTL is not 255 (or 255-
TrustRadius).
3.4. TCP-MD5 and Other Custom Authentication
At least BGP, MSDP, and LDP are able to use the TCP-MD5 signature
option to verify the authenticity of control packets. TCP-MD5 uses
manually configured static keys, and changing them must be a
coordinated event to prevent session reset. Due to the operational
cost of re-keying, the solution is sub-optimal in cases where (rather
paranoid) security procedures require (e.g., after an employee leaves
the organization) that the keys must be easily and often changeable.
Using TCP-MD5 and other similar authentication mechanisms (e.g., for
IGPs or BFD) also opens an attack vector for cryptographic exhaustion
attacks unless implementations have appropriate mechanisms to
throttle or otherwise manage heavy cryptographic operations.
3.5. IPsec and IKE
IPsec and IKE have been proposed as a more comprehensive
countermeasure, but these protocols also require a lot of heavyweight
protocol machinery, lots of configuration, and cryptographic
processing. Vendors have also expressed difficulty in applying IPsec
to control traffic protection.
4. Protocol Analysis
This Section briefly discusses the protocol-specific attack
properties below.
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ICMP attacks apply to all the IP protocols at least to some degree.
There is no reasonable way to appropriately protect from these
attacks by operative methods such as filtering: the vendors should
implement countermeasures described in [I-D.ietf-tcpm-icmp-attacks]
to mitigate these attacks.
4.1. OSPF
OSPF attacks have already been analyzed [I-D.ietf-rpsec-ospf-vuln].
In this context the most important of them are preventing (1)
misconfiguration and unauthorized neighbors, and (2) off-path
directed attacks as described in Section 4.1.2 of
[I-D.ietf-rpsec-ospf-vuln].
The former requires configuration change procedures and regular
audits of OSPF configuration, and disabling OSPF adjacencies on
customer-facing links, or adding authentication when there are
multiple routers. The latter requires using OSPF authentication,
dropping all OSPF traffic at all the borders, or moving to another,
less vulnerable protocol (e.g., IS-IS).
OSPF is also used to some degree with provider-provisioned VPNs by
the customers. In such scenarios, strict route filtering needs to be
applied to ensure only the valid prefixes are accepted.
4.2. IS-IS
Routing IP with IS-IS has gained popularity in the backbone networks
lately. As IS-IS does not use IP as its control protocol, external
attackers cannot attack IS-IS in the same way as they can attack
OSPF. Hence it is sufficient to prevent misconfiguration and
unauthorized neighbors, using similar countermeasures as with OSPF:
configuration change procedures and regular configuration audits and
disabling IS-IS adjacencies on customer-facing links, or adding
authentication when there are multiple routers.
4.3. BFD
Bidirectional Forwarding Detection (BFD) detects faults in the
forwarding path between two endpoints. As a generic mechanism, it
can be applied to a number of protocols (e.g., OSPF, IS-IS, BGP,
MPLS, or static routes).
When BFD is in use for a single-hop scenario, it uses GTSM to protect
from off-link attackers. Authentication can also be used for example
on untrusted links.
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4.4. BGP
Internal BGP sessions run between loopback addresses. There is no
need to run TCP-MD5 for outsider protection as address filtering will
avoid TCP RST attacks.
External BGP sessions may run multi-hop between loopback addresses or
single-hop between interface addresses. The latter case is much more
common and easier to protect and applying GTSM provides first-order
resistance to off-link attackers.
In any case, assuming address filtering, the session can only be
reset by the peer, or by attacks from the direction of the peer's
network (e.g., through lack of peer's border filtering). One can
therefore question the necessity of further protection as the peer
can only shoot itself in the foot by killing the BGP session or
allowing the BGP session be killed through negligence.
There is one exception to the above: if the customer is multihomed
through multiple ISPs and the addresses used for the peering session
are from the customer's address block. In such scenarios, using each
ISP's respective addresses for the peering link might be the simplest
approach.
If the link is not trusted (e.g., in some large Ethernet-based
Internet Exchange points), it may also be desirable to ensure that
peers are not able to reset others' sessions, so a mechanism like
TCP-MD5 may be appropriate. One should note that the security
requirements are not necessarily very high as the attacker should
already be easily traceable on a single link, and thus re-keying may
not be worth the trouble.
As BGP processes data heard from external sources, the routing data
can be modified in numerous ways, e.g., to create arbitrarily complex
advertisements using path attributes to crash naive BGP
implementations. These and many other BGP attacks are described in
[RFC4272]. Techniques described in Section 3.2 can mitigate the
attack vectors to some degree, but a more comprehensive solution to
securing routing data is needed.
4.5. Multicast Protocols (PIM, MSDP)
Multicast routing is typically achieved by PIM-SM
[I-D.ietf-mboned-routingarch]. MSDP is used for IPv4 source
discovery. Multicast routing protocol threats have been analyzed
separately in [RFC4609] (backbone perspective) and
[I-D.ietf-pim-lasthop-threats] (last-hop perspective).
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In summary, most of the multicast threats pertain to overloading
control processors via too much state. Implementation-specific rate-
limiters can help in mitigating the risk. If resetting MSDP sessions
is a concern, TCP-MD5 option similar to BGP can be used. Address
filtering can be applied in particular in PIM Unicast-Register
message decapsulation; other messages use multicast and already
employ reverse path forwarding checks.
5. Summary
IGPs require a great deal of care to ensure that they are not enabled
on links where they shouldn't be. Preventing external OSPF attacks
also requires OSPF authentication everywhere or filtering OSPF
packets at the edges.
ICMP attacks are able to cause a great deal of harm to almost all the
protocols, including IPsec, and there is little to do to mitigate the
risk except to implement enhanced ICMP payload verification/
processing techniques. More study of the impact on connectionless
protocols and IPsec should be conducted.
With border address filtering in place, internal sessions are
reasonably safe. With additional GTSM protection, external private
interconnection links are also reasonably safe, as the session can
only be reset by the neighbor or due to lack of filtering, someone
through the neighbor's network. TCP-MD5 protection is most
appropriate for Internet Exchange points with multiple neighbors or
multihop eBGP sessions, but it's worth remembering that the security
requirements for the solution are not very high as the attackers have
very strict topological restrictions.
IPsec and IKE are obviously an option for heavy-weight protection,
but impractical (yet) due to configuration complexity and processing
overhead. Simplifications in configuration, implementation, and
cryptographic hardware offloading might help the situation for the
cases where the use of heavier protection (e.g., possibly Internet
Exchange points) could be warranted.
6. IANA Considerations
This memo makes no request to IANA.
7. Acknowledgements
George Jones suggested improvements to the initial version of this
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draft. Further feedback was received from Sean P. Turner, Seo Boon
NG, Warren Kumari, Hank Nussbacher, Jonathan Trostle, Iljitsch van
Beijnum, and Barry Greene.
8. Security Considerations
This document does not define a protocol but rather describes and
analyzes the security properties and countermeasures in existing
service provider backbone network infrastructures.
The most important issues that should be noted are its security
assumptions:
o We require at least certain degree of address filtering at
borders, or else all bets are off. This assumption is notably NOT
satisfied by a number of networks.
o The main concern is an external attack (from customers or some
other network); lower-layer attacks are not considered a
particular concern for routing protocols.
o Generic DoS attacks against routers can be mitigated using
implementation-specific measures.
There are a number of actions for network operators in order to
protect the network (e.g., filtering OSPF packets at the edges or
auditing IGP configurations). There are also lessons to be learned
for protocol designers (e.g., OSPF external attacks, ICMP attacks
against non-TCP, use of GTSM). Many of the issues listed also depend
on vendors to implement effective, vendor-specific rate-limiting
techniques.
9. References
9.1. Normative References
[I-D.ietf-opsec-current-practices]
Kaeo, M., "Operational Security Current Practices",
draft-ietf-opsec-current-practices-07 (work in progress),
August 2006.
[I-D.ietf-rpsec-ospf-vuln]
Jones, E. and O. Moigne, "OSPF Security Vulnerabilities
Analysis", draft-ietf-rpsec-ospf-vuln-02 (work in
progress), June 2006.
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[I-D.ietf-rtgwg-rfc3682bis]
Gill, V., "The Generalized TTL Security Mechanism (GTSM)",
draft-ietf-rtgwg-rfc3682bis-08 (work in progress),
December 2006.
[I-D.ietf-tcpm-icmp-attacks]
Gont, F., "ICMP attacks against TCP",
draft-ietf-tcpm-icmp-attacks-01 (work in progress),
October 2006.
[I-D.ietf-tcpm-tcp-antispoof]
Touch, J., "Defending TCP Against Spoofing Attacks",
draft-ietf-tcpm-tcp-antispoof-05 (work in progress),
October 2006.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, May 2000.
[RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed
Networks", BCP 84, RFC 3704, March 2004.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis",
RFC 4272, January 2006.
[RFC4593] Barbir, A., Murphy, S., and Y. Yang, "Generic Threats to
Routing Protocols", RFC 4593, October 2006.
[RFC4609] Savola, P., Lehtonen, R., and D. Meyer, "Protocol
Independent Multicast - Sparse Mode (PIM-SM) Multicast
Routing Security Issues and Enhancements", RFC 4609,
October 2006.
9.2. Informative References
[BLOCKED] Cisco Systems, "Cisco Security Advisory: Cisco IOS
Interface Blocked by IPv4 Packets", 2004, <http://
www.cisco.com/warp/public/707/
cisco-sa-20030717-blocked.shtml>.
[CVE] CVE-2004-0790, "Multiple TCP/IP and ICMP implementations
allow remote attackers to cause a denial of service (reset
TCP connections) via spoofed ICMP error messages, aka the
"blind connection-reset attack."", 2004, <http://
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-0790>.
[I-D.ietf-mboned-routingarch]
Savola, P., "Overview of the Internet Multicast Routing
Savola Expires July 20, 2007 [Page 14]
Internet-Draft Attacks Against Backbone January 2007
Architecture", draft-ietf-mboned-routingarch-07 (work in
progress), November 2006.
[I-D.ietf-opsec-filter-caps]
Morrow, C., "Filtering and Rate Limiting Capabilities for
IP Network Infrastructure",
draft-ietf-opsec-filter-caps-04 (work in progress),
September 2006.
[I-D.ietf-pim-lasthop-threats]
Savola, P. and J. Lingard, "Last-hop Threats to Protocol
Independent Multicast (PIM)",
draft-ietf-pim-lasthop-threats-00 (work in progress),
October 2006.
[I-D.ietf-tcpm-tcpsecure]
Ramaiah, A., "Improving TCP's Robustness to Blind In-
Window Attacks", draft-ietf-tcpm-tcpsecure-06 (work in
progress), November 2006.
[I-D.zinin-rtg-dos]
Zinin, A., "Protecting Internet Routing Infrastructure
from Outsider DoS Attacks", draft-zinin-rtg-dos-02 (work
in progress), May 2005.
[MYASN] RIPE NCC, "MyASn System",
<http://www.ris.ripe.net/myasn.html>.
[RFC4732] Handley, M., Rescorla, E., and IAB, "Internet Denial-of-
Service Considerations", RFC 4732, December 2006.
Author's Address
Pekka Savola
CSC/FUNET
Espoo
Finland
Email: psavola@funet.fi
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Internet-Draft Attacks Against Backbone January 2007
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