Internet Engineering Task Force Curtis Villamizar
INTERNET-DRAFT UUNET
draft-ietf-rps-auth-03 Cengiz Alaettinoglu
ISI
David M. Meyer
Cisco
Sandy Murphy
TIS
April 22, 1999
Routing Policy System Security
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.
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Copyright (C) The Internet Society (April 22, 1999). All Rights Re-
served.
Abstract
The RIPE database specifications and RPSL language define languages
used as the basis for representing information in a routing policy
system. A repository for routing policy system information is known
as a routing registry. A routing registry provides a means of ex-
INTERNET-DRAFT Routing Policy System Security April 22, 1999
changing information needed to address many issues on importance to
the operation of the Internet. The implementation and deployment of
a routing policy system must maintain some degree of integrity to be
of any operational use. This document addresses the need to assure
integrity of the data by providing an authentication and authorization
model.
1 Overview
The Internet Routing Registry (IRR) has evolved to meet a need for
Internet-wide coordination. This need was described in RFC-1787, an
informational RFC prepared on behalf of the IAB [16]. The following
summary appears in Section 7 of RFC-1787.
While ensuring Internet-wide coordination may be more and more
difficult, as the Internet continues to grow, stability and con-
sistency of the Internet-wide routing could significantly benefit
if the information about routing requirements of various organi-
zations could be shared across organizational boundaries. Such
information could be used in a wide variety of situations ranging
from troubleshooting to detecting and eliminating conflicting
routing requirements. The scale of the Internet implies that the
information should be distributed. Work is currently underway to
establish depositories of this information (Routing Registries),
as well as to develop tools that analyze, as well as utilize this
information.
A routing registry must maintain some degree of integrity to be of
any use. The degree of integrity required depends on the usage of the
routing policy system.
An initial intended usage of routing policy systems such as the RIPE
database had been in an advisory capacity, documenting the intended
routing policies for the purpose of debugging. In this role a very
weak form of authentication was deemed sufficient.
The IRR is increasingly used for purposes that have a stronger re-
quirement for data integrity and security. This document addresses
issues of data integrity and security that is consistent with the
usage of the IRR and which avoids compromising data integrity and se-
curity even if the IRR is distributed among less trusted repositories.
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2 Background
An early routing policy system used in the NSFNET, the policy routing
database (PRDB), provided a means of determining who was authorized
to announce specific prefixes to the NSFNET backbone. The need for
a policy database was recognized as far back as 1989 [6, 4]. By 1991
the database was in place [5]. Authentication was accomplished by
requiring confirmation and was a manually intensive process. This
solved the problem for the NSFNET, but was oriented toward holding the
routing policy of a single organization.
The problem since has become more difficult. New requirements have
emerged.
1. There is a need to represent the routing policies of many organiza-
tions.
2. CIDR and overlapping prefixes and the increasing complexity of
routing policies and the needs of aggregation have introduced new
requirements.
3. There is a need to assure integrity of the data and delegate au-
thority for the data representing specifically allocated resources
to multiple persons or organizations.
4. There is a need to assure integrity of the data and distribute the
storage of data subsets to multiple repositories.
The RIPE effort specificly focused on the first issue and needs of the
European community. Its predecessor, the PRDB, addressed the needs of
a single organization, the NSF. The RIPE database formats as described
in [2] were the basis of the original IRR.
Routing protocols themselves provide no assurance that the origination
of a route is legitimate and can actually reach the stated destina-
tion. The nature of CIDR allows more specific prefixes to override
less specific prefixes [9, 17 , 8]. Even with signed route origina-
tion, there is no way to determine if a more specific prefix is legit-
imate and should override a less specific route announcement without a
means of determining who is authorized to announce specific prefixes.
Failing to do so places no assurance of integrity of global routing
information and leaves an opportunity for a very effective form of
denial of service attack.
The Routing Policy System Language (RPSL) [1, 13 ] was a fairly sub-
stantial evolutionary step in the data representation which was
largely targeted at addressing the second group of needs. The PRDB
accommodated CIDR in 1993 [12] and the RIPE database accommodated the
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entry of CIDR prefixes from inception, but RPSL provides many needed
improvements including explicit support for aggregation.
This document addresses the third group of needs identified above.
While the current implementation supporting weak authentication
doesn't guarantee integrity of the data, it does provide extensive
mechanisms to make sure that all involved parties get notified when
a change is made to the database, whether the change was malicious
or intended. This provides inadequate protection against additions.
Since the software is increasingly used to configure the major parts
of the Internet infrastructure, it is not considered to be adequate
anymore to know about and have the ability roll back unintended
changes. Therefore, more active security mechanism need to be de-
veloped to prevent such problems before they happen.
A separate document will be needed to address the fourth group of
needs.
3 Implicit Policy Assumptions
The authorization model encodes certain policies for allocation of
address numbers, AS numbers, and for the announcement of routes. Im-
plicit to the authorization model are a very limited number of policy
assumptions.
1. Address numbers are allocated hierarchically. The IANA delegates
portions of the address space to the regional registries (currently
ARIN, APNIC and RIPE), which in turn delegate address space to
their members, who can assign addresses to their customers.
2. AS numbers are allocated either singly or in small blocks by reg-
istries. Registries are allocated blocks of AS numbers, thereby
making the allocation hierarchical.
3. Routes should only be announced with the consent of the holder of
the origin AS number of the announcement and with the consent of
the holder of the address space.
4. AS numbers and IP address registries may be different entities from
routing registries.
For subsets of any of these three allocation spaces, network ad-
dresses, AS numbers, and routes, these restrictions may be loosened
or disabled by specifying a very weak authorization method or an
authentication method of ``none''. However, even when no authenti-
cation mechanism is used, all involved parties can be notified about
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the changes that occurred through use of the existing ``notify'' at-
tribute.
4 Scope of Security Coverage
This document is intended only to provide an authentication and au-
thorization model to insure the integrety of the policy data in a reg-
istry. Only authetication and authorization of additions, deletions,
and changes to the database are within the scope of this document.
Authentication and authorization of database queries is explicitly
out of scope. Mutual authentication of queries, that is authenticat-
ing both the origin of the query and the repository from which query
results are obtained, is also out of scope.
5 Organization of this Document
Familiarity with RIPE-181 [2] and RPSL [1] is assumed throughout this
document. Goals are described in Section 6. Section 7 through Sec-
tion 9 provide descriptions of the changes and discussion. Section 10
provides a concise summary of data formats and semantics. Appendix B
through Appendix D provide additional technical discussion, examples,
and deployment considerations.
Goals and Requirements Section 6 provides a more detailed descrip-
tion of the issues and identifies specific problems that need to
be solved, some of which require a degree of cooperation in the
Internet community.
Data Representation Section 7 provides some characteristics of RPSL
and formats for external representations of information.
Authentication Model Section 8 describes current practice, proposes
additional authentication methods, and describes the extension
mechanism if additional methods are needed in the future.
Authorization Model Section 9 describes the means of determining
whether a transaction contains the authorization needed to add,
modify, or delete specific data objects, based on stated authenti-
cation requirements in related data objects.
Data Format Summaries Section 10 provides a concise reference to
the data formats and steps in transaction processing.
Technical Discussion Section B contains some discussion of techni-
cal tradeoffs.
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Common Operational Cases Section C provides some examples drawn
from past operational experience with the IRR.
Deployment Considerations Section D describes some deployment is-
sues and discusses possible means of resolution.
6 Goals and Requirements
The Internet is an open network. This openness and the large scale of
the Internet can present operational problems. Technical weaknesses
that allow misconfiguration or errant operation in part of the network
to propagate globally or which provide potentials for simple denial
of service attacks should be eliminated to the extent that it is prac-
tical. The integrity of routing information is critical in assuring
that traffic goes where it is supposed to.
An accidental misconfiguration can direct traffic toward routers that
cannot reach a destination for which they are advertising reachabil-
ity. This is commonly caused by misconfigured static routes though
there are numerous other potential causes. Static routes are often
used to provide constant apparent reachability to single homed desti-
nations. Some of the largest ISPs literally have thousands of static
routes in their networks. These are often entered manually by op-
erators. Mistyping can divert traffic from a completely unrelated
destination to a router with no actual reachability to the advertised
destination. This can happen and does happen somewhat regularly. In
addition, implementation bugs or severe misconfigurations that result
in the loss of BGP AS path information or alteration of prefix length
can result in the advertisement of large sets of routes. Though con-
siderably more rare, on a few occasions where this has occurred the
results were catastrophic.
Where there is the potential for an accidental misconfiguration in
a remote part of the Internet affecting the global Internet there is
also the potential for malice. For example, it has been demonstrated
by accident that multiple hour outages at a major institution can be
caused by a laptop and a dial account if proper precautions are not
taken. The dial account need not be with the same provider used by
the major institution.
The potential for error is increased by the CIDR preference for more
specific routes [8]. If an institution advertises a single route of
a given length and a distant router advertises a more specific router
covering critical hosts, the more specific route, if accepted at all,
is preferred regardless of administrative weighting or any routing
protocol attributes.
There is a need to provide some form of checks on whether a route ad-
vertisement is valid. Today checks are typically made against the
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border AS advertising the route. This prevents accepting routes from
the set of border AS that could not legitimately advertise the route.
Theses checks rely on the use of information registered in the IRR
to generate lists of prefixes that could be advertised by a specific
border AS. Checks can also be made against the origin AS. If policy
information were sufficiently populated, checks could be made against
the entire AS path, but this is not yet feasible.
The use of a routing registry can also make it more difficult for pre-
fixes to be used without authorization such as unallocated prefixes or
prefixes allocated to another party.
In summary, some of the problems being addressed are:
o Localizing the impact of accidental misconfiguration made by Inter-
net Providers to that provider's networks only.
o Eliminating the potential for an Internet provider's customer to
use malicious misconfiguration of routing as a denial of service
attack if the provider router filters their customers. Localizing
the denial of service to that Internet provider only if the immedi-
ate Internet service provider does not route filter their customers
but other providers route filter the route exchange at the inter-
provider peering.
o Eliminating the unauthorized use of address space.
If the data within a routing registry is critical, then the ability
to change the data must be controlled. Centralized authorities can
provide control but centralization can lead to scaling problems (and
is politically distasteful).
Address allocation and name allocation is already delegated. Since
delegation can be to outside registries it is at least somewhat dis-
tributed [11]. Autonomous System (AS) numbers are allocated by the
same authorities. It makes sense to delegate the routing number space
in a manner similar to the address allocation and AS number alloca-
tion. The need for this delegation of authority to numerous reg-
istries increases the difficulty of maintaining the integrity of the
body of information as a whole.
As a first step, the database can be somewhat centrally administered
with authority granted to many parties to change the information.
This is the case with the current IRR. There are a very small number
of well trusted repositories and a very large number of parties au-
thorized to make changes. Control must be exercised over who can make
changes and what changes they can make. The distinction of who vs
what separates authentication from authorization.
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o Authentication is the means to determine who is attempting to make
a change.
o Authorization is the determination of whether a transaction pass-
ing a specific authentication check is allowed to perform a given
operation.
Different portions of the database will require different methods of
authentication. Some applications will require authentication based
on strong encryption. In other cases software supporting strong en-
cryption may not be necessary or may not be legally available. For
this reason multiple authentication methods must be supported, se-
lected on a per object basis through the specification of authen-
tication methods in the maintainer object ``auth'' attribute. The
authentication methods may range from very weak data integrity checks
to cryptographicly strong signatures. The authorization model must
insure that the use of weak integrity checks in parts of the database
does not compromise the overall integrity of the database.
Additional requirements are placed on the authorization model if the
database is widely distributed with delegations made to parties that
may not be trustworthy or whose security practices may be lacking.
This problem must be addressed in the authorization model in order to
enable later evolution to a more distributed routing registry.
Autonomous system numbers can be delegated in blocks and subdelegated
as needed and then individual AS numbers assigned. Address alloca-
tion is a simple numeric hierarchy. Route allocation is somewhat
more complicated. The key attributes in a route object (key with re-
gard to making it unique) contains both an address prefix and an AS
number, known as the origin AS. The addition of a route object must
be validated against both the authorization criteria for the AS and
the address prefix. Route objects may exist for the same prefix with
multiple origin AS values due to a common multihoming practice that
does not require a unique origin AS. There is often no correlation be-
tween the origin AS of a prefix and the origin AS of overlapping more
specific prefixes.
There are numerous operational cases that must be accommodated. Some
of the more common are listed below. These are explored in greater
detail in Appendix C with discussion of technical tradeoffs in Ap-
pendix B.
o simple hierarchical address allocation and route allocation
o aggregation and multihomed more specific routes
o provider independent addresses and multiple origin AS
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o changing Internet service providers
o renumbering grace periods
The authorization model must accommodate a variety of policies regard-
ing the allocation of address space and cannot mandate the use of any
one model. There is no standardization of address allocation policies
though guidelines do exist [11, 18 ]. Whether authorization allows the
recovery of address space must be selectable on a per object basis and
may differ in parts of the database. This issue is discussed further
in Appendix B.
7 Data Representation
RPSL provides a complete description of the contents of a routing
repository [1]. Many RPSL data objects remain unchanged from the RIPE
and RPSL references the RIPE-181 specification as recorded in RFC-1786
[2]. RPSL provides external data representation. Data may be stored
differently internal to a routing registry.
Some database object types or database attributes must be added to
RPSL to record the delegation of authority and to improve the authen-
tication and authorization mechanisms. These additions are very few
and are described in Section 8 and Section 9.
Some form of encapsulation must be used to exchange data. The de-
facto encapsulation has been the one which the RIPE tools accept, a
plain text file or plain text in the body of an RFC-822 formatted mail
message with information needed for authentication derived from the
mail headers or the body of the message. Merit has slightly modified
this using the PGP signed portion of a plain text file or PGP signed
portion of the body of a mail message. These very simple forms of
encapsulation are suitable for the initial submission of a database
transaction.
The encapsulation of registry transaction submissions, registry
queries and registry responses and exchanges between registries is
outside the scope of this document. The encapsulation of registry
transaction submissions and exchanges between registries is outside
the scope of this document.
8 Authentication Model
The maintainer objects serve as a container to hold authentication
filters. A reference to a maintainer within another object defines
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authorization to perform operations on the object or on a set of re-
lated objects. The maintainer is typically referenced by name in mnt-
by attributes of objects. Further details on the use of maintainers
are provided in Section 9.1.
The maintainer contains one or more ``auth'' attributes. Each
``auth'' attribute begins with a keyword identifying the authenti-
cation method followed by the authentication information needed to
enforce that method. The PGPKEY method is slightly syntactically
different in that the method PGPKEY is a substring.
Authentication methods currently supported include the following.
Note that pgp-from is being replaced by the pgpkey (see Section 10 and
[21]).
mail-from This is a very weak authentication check and is discour-
aged. The authentication information is a regular expression over
ASCII characters. The maintainer is authenticated if the from or
reply-to fields in RFC-822 mail headers are matched by this regular
expression. Since mail forgery is quite easy, this is a very weak
form of authentication.
crypt-pw This is another weak form of authentication. The authenti-
cation information is a fixed encrypted password in UNIX crypt for-
mat. The maintainer is authenticated if the transaction contains
the clear text password of the maintainer. Since the password
is in clear text in transactions, it can be captured by snooping.
Since the encrypted form of the password is exposed, it is subject
to password guessing attacks.
pgp-from This format is being replaced by the ``pgpkey'' so that the
public key certificate will be available to remote repositories.
This is Merit's PGP extension. The authentication information
is a signature identity pointing to an external public key ring.
The maintainer is authenticated if the transaction (currently PGP
signed portion of a mail message) is signed by the corresponding
private key.
pgpkey This keyword takes the form ``PGPKEY-hhhhhhhh'', where ``hh-
hhhhhh'' is the hex representation of the four bytes id of the PGP
public key used for authentication. The public key certificate is
stored in a separate object as described in [21].
Repositories may elect to disallow the addition of ``auth'' attributes
specifying weaker forms of authentication and/or disallow their use
in local transaction submissions. Repositories are encouraged to dis-
allow the addition of ``auth'' attributes with the deprecated ``pgp-
from'' method.
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Any digital signature technique can be used for authentication.
Transactions should be signed using multiple digital signature tech-
niques to allow repositories or mirrors that only use a subset of the
techniques to verify at least one of the signatures. Any digital sig-
nature techniques would be applicable. One that may be supported in
the in the future is DSA [14, 15 ]. Numerous digital signature algo-
rithms are described in [20].
9 Authorization Model
The authorization model must accommodate the requirements outlined
in Section 6. A key feature of the authorization model is the recog-
nition that authorization for the addition of certain types of data
objects must be derived from related data objects.
With multiple repositories, objects not found in RPSL are needed to
control AS delegations and new attributes are needed in existing ob-
jects to control subdelegation. Objects are also needed to provide
query information for other repositories.
9.1 Maintainer Objects
The maintainer objects serve as a container to hold authentication
filters. The authentication methods are described in Section 8. The
maintainer can be referenced by name in other objects, most notably in
the mnt-by attributes of those objects.
Maintainers themselves contain mnt-by attributes. In some cases the
mnt-by in a maintainer will reference the maintainer itself. In this
case, authorization to modify the maintainer is provided to a (usu-
ally very limited) set of identities. A good practice is to create
a maintainer containing a long list of identities authorized to make
specific types of changes but have the maintainer's mnt-by attribute
reference a far more restrictive maintainer more tightly controlling
changes to the maintainer object itself.
The mnt-by attribute is mandatory in all objects. Some data already
exists without mnt-by attributes. A missing mnt-by attribute is in-
terpreted as the absence of any control over changes. This is highly
inadvisable and most repositories will no longer allow this.
An additional maintainer reference can occur through a new attribute,
``mnt-routes'', and is used in aut-num, inetnum and route objects.
The ``mnt-routes'' attribute is an extension to RPSL and is described
in detail in Section 10.
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A mnt-routes attribute in an aut-num object allows addition of route
objects with that AS number as the origin to the maintainers listed.
A mnt-routes attribute in an inetnum object allows addition of route
objects with exact matching or more specific prefixes. A mnt-routes
attribute in a route object allows addition of route objects with ex-
act matching or more specific prefixes. A mnt-routes attribute does
not allow changes to the aut-num, inetnum, or route object where they
appear. A mnt-routes may optionally be constrained to only apply to a
subset of more specific routes.
Where ``mnt-routes'' or ``mnt-lower'' are applicable, any maintainer
referenced in the ``mnt-by'' still apply. The set of applicable main-
tainers for whatever check is being made is the union of the ``mnt-
routes'' or ``mnt-lower'' and the ``mnt-by''. For example, when au-
thorizing a route object software would look at ``mnt-routes'', if it
does not exist, look at ``mnt-lower'', if that does not exist look at
``mnt-by''.
9.2 as-block and aut-num objects
An ``as-block'' object is needed to delegate a range of AS numbers to
a given repository. This is needed for authorization and it is needed
to avoid having to make an exhaustive search of all repositories to
find a specific AS. This search would not be an issue now but would
be if a more distributed routing repository is used. Distributed
registry issues are not within the scope of this document.
The ``as-block'' object also makes it possible to separate AS number
allocation from registration of AS routing policy.
as-block: AS1321 - AS1335
...
The ``aut-num'' describes the routing policy for an AS and is criti-
cal for router configuration of that AS and for analysis performed by
another AS. For the purpose of this document it is sufficient to con-
sider the aut-num solely as a place holder identifying the existence
of an AS and providing a means to associate authorization with that AS
when adding ``route'' objects.
The ``as-block'' object is proposed here solely as a means of record-
ing the delegation of blocks of AS numbers to alternate registries and
in doing so providing a means to direct queries and a means to support
hierarchical authorization across multiple repositories.
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9.3 inetnum objects
A delegation attribute is needed in the inetnum and route object.
This will accommodate the delegation of address space from IANA to
regional IP registries. When the routing registry becomes more widely
distributed a delegation attribute is needed to support any subdelega-
tions to more localized registries or delegations to Internet provider
operated registries or organizations who may prefer to run their own
routing registry. The delegation attribute for an inetnum or a route
object can be multi-valued and refers to all registries in which more
specific route objects can be found.
inetnum: 193.0.0.0 - 193.0.0.255
...
source: IANA
The ``inetnum'' exists to support address allocation. For external
number registries, such as those using ``[r]whoisd[++]'' the ``inet-
num'' can serve as a secondary record that is added when an address
allocation is made in the authoritative database. Such records could
be added by a address registry such as ARIN as a courtesy to the cor-
responding routing registry.
9.4 route objects
Currently there are a quite few route objects in more than one reg-
istry. Quite a few are registered with origin AS for which they have
never been announced. There is a legitimate reason to be in more than
one origin AS.
The ``route'' object is used to record routes which may appear in the
global routing table. Explicit support for aggregation is provided.
Route objects exist both for the configuration of routing information
filters used to isolate incidents of erroneous route announcements
(Section 6) and to support network problem diagnosis.
9.5 reclaim and no-reclaim attributes
A reclaim attribute is needed in as-block, inetnum and route objects.
The reclaim attribute allows a control to be retained over more spe-
cific AS, IP address or route space by allowing modify and delete
privileges regardless of the mnt-by in the object itself.
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The reclaim attribute provides the means to enforce address lending.
It allows cleanup in cases where entities cease to exist or as a last
resort means to correct errors such as parties locking themselves out
of access to their own objects. To specify all more specific objects
the reclaim attribute value should be ``ALL''. To allow finer control
a set of prefixes can be specified.
A no-reclaim attribute can be used to provide explicit exceptions. A
reclaim attribute can only be added to an existing object if the ad-
dition of the reclaim attribute does not remove autonomy of existing
more specific objects that are covered by the new reclaim attribute.
1. A reclaim attribute can be added to an existing object if there are
no existing exact matches or more specific objects overlapped by
the new reclaim attribute, or
2. if the submitter is listed in the maintainer pointed to by the mnt-
by of the objects which are overlapped, or
3. if any overlapped object is listed in a no-reclaim attribute in the
object where the reclaim is being added.
Similarly, a submitter may delete a no-reclaim attribute from an ob-
ject only when that submitter is the only maintainer listed in the
mnt-by attributes of any overlapped objects. If the submitter is not
listed in any of the maintainers pointed to by the mnt-by attributes
for one or more overlapped object, then the submitter is not permitted
to delete the no-reclaim attribute.
If neither a reclaim or no-reclaim attribute is present, then more
specific objects of a given object cannot be modified by the main-
tainer of the less specified object unless the maintainer is also
listed as a maintainer in the more specific object. However, the ad-
dition of a new route or inetnum object must pass authentication of
the largest less specific prefix as part of the authentication check
described in Section 9.9.
See Section 10 for a full description of the reclaim and no-reclaim
attributes.
9.6 Other Objects
Many of the RPSL ancillary objects have no natural hierarchy the way
AS numbers, Internet addresses and routes do have a numeric hierarchy.
Some examples are ``maintainers'', ``people'' and ``role'' objects.
For these objects, lack of any hierarchy leads to two problems.
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1. There is no hierarchy that can be exploited to direct queries to
alternate registries. At some point the query strategy of search-
ing all known registries becomes impractical.
2. There is no hierarchy on which authorizations of additions can be
based.
The first problem can be addressed by considering the name space
for each of the ancillary objects to be unique only within the lo-
cal database and to use explicit references to an external repository
where needed. To specify an external repository reference, the ob-
ject key is preceded by the name of the repository and the delimiter
``::''. For example a NIC handle may take the form ``RIPE::CO19''.
Currently there is a desire to keep NIC handles unique so the nam-
ing convention of appending a dash and the repository name is used.
Prepending the repository name provides the unique name space since an
object in the RIPE database referencing ``CO19'' would be interpreted
as ``RIPE::CO19'' by default, but it would still be possible to query
or reference ``IANA::CO19''. There is no possibility of accidentally
forgetting to adhere to the conventions when making an addition and
the existing objects are accommodated, including cases where name
conflicts have already occurred.
The second problem can be partially addressed by using a referral
system for the addition of maintainers and requiring that any other
object be submitted by a registered maintainer. The referral system
would allow any existing maintainer to add another maintainer. This
can be used in parallel with the addition of other object types to
support the maintenance of those objects. For example, when adding
a subdomain to the ``domain'' hierarchy (in the RIPE repository where
domains are also handled), even when adding a new domain to a rela-
tively flat domain such as ``com'', there is already a maintainer for
the existing domain. The existing maintainer can add the maintainer
that will be needed for the new domain in addition to adding the new
domain and giving the new maintainer the right to modify it.
An organization gaining a presence on the Internet for the first time
would be given a maintainer. This maintainer may list a small number
of very trusted employees that are authorized to modify the maintainer
itself. The organization itself can then add another maintainer list-
ing a larger set of employees but listing the more restrictive main-
tainer in the mnt-by attributes of the maintainers themselves. The
organization can then add people and role objects as needed and any
other objects as needed and as authorization permits.
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9.7 Objects with AS Hierarchical Names
Many RPSL objects do not have a natural hierarchy of their own but al-
low hierarchical names. Some examples are the object types ``as-set''
and ``route-set''. An as-set may have a name corresponding to no nam-
ing hierarchy such as ``AS-Foo'' or it may have a hierarchical name of
the form ``AS1:AS-Bar''.
When a hierarchical name is not used, authorization for objects such
as ``as-set'' and ``route-set'' correspond to the rules for objects
with no hierarchy described in Section 9.6.
If hierarchical names are used, then the addition of an object must
be authorized by the aut-num whose key is named by everything to the
left of the rightmost colon in the name of the object being added.
Authorization is determined by first using the mnt-lower maintainer
reference, or if absent, using the mnt-by reference.
9.8 Query Processing
A query may have to span multiple repositories. All queries should
be directed toward a local repository which may mirror the root repos-
itory and others. Currently each IRR repository mirrors all others
repositories. In this way, the query may be answered by the local
repository but draw data from others.
For object types that have a natural hierarchy, such as aut-num, inet-
num, and route, the search begins at the root database and follows
the hierarchy. For objects types that have no natural hierarchy, such
as maintainer, person, and role objects, the search is confined to a
default database unless a database is specified. The default database
is the same database as an object from which a reference is made if
the query is launched through the need to follow a reference. Other-
wise the default is generally the local database or a default set by
the repository. The default can be specified in the query itself as
described in Section 9.7.
In searching for an AS, the delegation attribute in AS blocks can be
consulted, moving the search to data from other repositories. Eventu-
ally the AS is either found or the search fails.
The search for an inetnum is similar. Less specific inetnums may
refer the search to other databases. Eventually the most specific
inetnum is found and its status (assigned or not assigned) can be
determined.
The search for a route is similar except the search may branch to
more than one repository. The most specific route in one repository
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may be more specific than the most specific in another. In looking
for a route object it makes sense to return the most specific route
that is not more specific than the query requests regardless of which
repository that route is in rather than return one route from each
repository that contains a less specific overlap.
9.9 Adding to the Database
The root repository must be initially populated at some epoch with a
few entries. An initial maintainer is needed to add more maintain-
ers. The referral-by attribute can be set to refer to itself in this
special case (Section 10 describes the referral-by). When adding an
inetnum or a route object an existing exact match or a less specific
overlap must exist. A route object may be added based on an exact
match or a less specific inetnum. The root repository must be ini-
tially populated with the allocation of an inetnum covering the prefix
0/0, indicating that some address allocation authority exists. Simi-
larly an initial as-block is needed covering the full AS number range.
When adding an object with no natural hierarchy, the search for an
existing object follows the procedure outlined in Section 9.8.
When adding an aut-num (an AS), the same procedure used in a query is
used to determine the appropriate repository for the addition and to
determine which maintainer applies. The sequence of AS-block objects
and repository delegations is followed. If the aut-num does not ex-
ist, then the submission must match the authentication specified in
the maintainer for the most specific AS-block in order to be added.
The procedure for adding an inetnum is similar. The sequence of inet-
num blocks is followed until the most specific is found. The submis-
sion must match the authentication specified in the maintainer for the
most specific inetnum overlapping the addition.
Adding a route object is somewhat more complicated. The route object
submission must satisfy two authentication criteria. It must match
the authentication specified in the aut-num and the authentication
specified in either a route object or if no applicable route object is
found, then an inetnum.
An addition is submitted with an AS number and prefix as its key. If
the object already exists, then the submission is treated as a modify
(see Section 9.10). If the aut-num does not exist on a route add,
then the addition is rejected (see Section B for further discussion
of tradeoffs). If the aut-num exists then the submission is checked
against the applicable maintainer. A search is then done for the
prefix first looking for an exact match. If the search for an exact
match fails, a search is made for the longest prefix match that is
less specific than the prefix specified. If this search succeeds it
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will return one or more route objects. The submission must match an
applicable maintainer in at least one of these route objects for the
addition to succeed. If the search for a route object fails, then
a search is performed for an inetnum that exactly matches the prefix
or for the most specific inetnum that is less specific than the route
object submission. The search for an inetnum should never fail but it
may return an unallocated or reserved range. The inetnum status must
be ``allocated'' and the submission must match the maintainer.
Having found the AS and either a route object or inetnum, the autho-
rization is taken from these two objects. The applicable maintainer
object is any referenced by the mnt-routes attributes. If one or more
mnt-routes attributes are present in an object, the mnt-by attributes
are not considered. In the absence of a mnt-routes attribute in a
given object, the mnt-by attributes are used for that object. The
authentication must match one of the authorizations in each of the two
objects.
If the addition of a route object or inetnum contains a reclaim at-
tribute, then any more specific objects of the same type must be ex-
amined. The reclaim attribute can only be added if there are no more
specific overlaps or if the authentication on the addition is present
in the authorization of a less specific object that already has a re-
claim attribute covering the prefix range, or if the authentication on
the addition is authorized for the modification of all existing more
specific prefixes covered by the addition.
9.10 Modifying or Deleting Database Objects
When modifying or deleting any existing object a search for the object
is performed as described in Section 9.8. If the submission matches
an applicable maintainer for the object, then the operation can pro-
ceed. An applicable maintainer for a modification is any maintainer
referenced by the mnt-by attribute in the object. For route and inet-
num objects an applicable maintainer may be listed in a less specific
object with a reclaim attribute.
If the submission is for a route object, a search is done for all
less specific route objects and inetnums. If the submission is for
an inetnum, a search is done for all less specific inetnums. If the
submission fails the authorization in the object itself but matches
the reclaim attribute in any of the less specific objects, then the
operation can proceed. Section B contains discussion of the rationale
behind the use of the reclaim attribute.
A modification to an inetnum object that adds a reclaim attribute
or removes a no-reclaim attribute must be checked against all exist-
ing inetnums that are more specific. The same check of the reclaim
attribute that is made during addition must be made when a reclaim
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attribute is added by a modification (see Section 9.9).
A deletion is considered a special case of the modify operation. The
deleted object may remain in the database with a ``deleted'' at-
tribute in which case the mnt-by can still be consulted to remove
the ``deleted'' attribute.
10 Data Format Summaries
RIPE-181 [2] and RPSL [1] data is represented externally as ASCII
text. Objects consist of a set of attributes. Attributes are name
value pairs. A single attribute is represented as a single line with
the name followed by a colon followed by whitespace characters (space,
tab, or line continuation) and followed by the value. Within a value
all whitespace is equivalent to a single space. Line continuation is
supported by a backslash at the end of a line or the following line
beginning with whitespace. When transferred, externally attributes
are generally broken into shorter lines using line continuation though
this is not a requirement. An object is externally represented as a
series of attributes. Objects are separated by blank lines.
There are about 80 attribute types in the current RIPE schema and
about 15 object types. Some of the attributes are mandatory in cer-
tain objects. Some attributes may appear multiple times. One or
more attributes may form a key. Some attributes or sets of attributes
may be required to be unique across all repositories. Some of the
attributes may reference a key field in an object type and may be
required to be a valid reference. Some attributes may be used in
inverse lookups.
A review of the entire RIPE or RPSL schema would be too lengthy to
include here. Only the differences in the schema are described.
10.1 Changes to the RIPE/RPSL Schema
One new object type and several attributes are added to the RIPE/RPSL
schema. There are significant changes to the rules which determine if
the addition of an object is authorized.
The new object type is listed below. The first attribute listed is
the key attribute and also serves as the name of the object type.
as-block key mandatory single unique
descr optional multiple
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remarks optional multiple
admin-c mandatory multiple
tech-c mandatory multiple
notify optional multiple
mnt-by mandatory multiple
changed mandatory multiple
source mandatory single
In the above object type only the key attribute ``as-block'' is new:
as-block This attribute provides the AS number range for an ``as-
block'' object. The format is two AS numbers including the sub-
string ``AS'' separated by a ``-'' delimiter and optional whites-
pace before and after the delimiter.
In order to support stronger authentication, the following keywords
are added to the ``auth'' attribute:
pgp-from The remainder of the attribute gives the string identify-
ing a PGP identity whose public key is held in an external keyring.
The use of this method is deprecated in favor of the ``pgpkey''
method.
pgpkey See [21].
In order to disable authentication and give permission to anyone, the
authentication method ``none'' is added. It has no arguments.
An additional change is the ``auth'' attribute is allowed to exist
in a ``person'' or ``role'' object. The ``auth'' method ``role'' or
``person'' can be used to refer to a role or person object and take
the ``auth'' fields from those objects. Care must be taken in imple-
mentations to detect circular references and terminate expansion or
the references already visited.
A few attributes are added to the schema. These are:
mnt-routes The mnt-routes attribute may appear in an aut-num, inet-
num, or route object. This attribute references a maintainer ob-
ject which is used in determining authorization for the addition of
route objects. After the reference to the maintainer, an optional
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list of prefix ranges (as defined in RPSL) inside of curly braces
or the keyword ``ANY'' may follow. The default, when no additional
set items are specified is ``ANY'' or all more specifics. The mnt-
routes attribute is optional and multiple. See usage details in
Section 9.1.
mnt-lower The mnt-lower attribute may appear in an inetnum, route,
as-block or aut-num object. This attribute references a maintainer
object. When used in an inetnum or route object the effect is the
same as a ``mnt-routes'' but applies only to prefixes more specific
than the prefix of the object in which it is contained. In an as-
block object, mnt-lower allows addition of more specific as-block
objects or aut-num objects. In an aut-num object the mnt-lower at-
tribute specifies a maintainer that can be used to add objects with
hierarchical names as described in Section 9.7.
reclaim The reclaim attribute may appear in as-block, aut-num, inet-
num, or route objects. Any object of the same type below in the
hierarchy may be modified or deleted by the maintainer of the ob-
ject containing a reclaim attribute. The value of the attribute is
a set or range of objects of the same type where the syntax of the
set or range is as defined in RPSL. See Section 9.5 for restric-
tions on adding reclaim attributes.
no-reclaim The no-reclaim attribute is used with the reclaim at-
tribute. The no-reclaim attribute negates any reclaim attribute it
overlaps. See Section 9.5 for restrictions on deleting no-reclaim
attributes.
referral-by This attribute is required in the maintainer object. It
may never be altered after the addition of the maintainer. This
attribute refers to the maintainer that created this maintainer.
It may be multiple if more than one signature appeared on the
transaction creating the object.
auth-override An auth-override attribute can be added, deleted, or
changed by a transaction submitted by maintainer listed in the
referral-by. An auth-override can only be added to a maintainer
if that maintainer has been inactive for the prior 60 days. The
auth-override attribute itself contains only the date when the at-
tribute will go into effect which must be at least 60 days from the
current date unless there is already authorization to modify the
maintainer. After the date in the auth-override is reached, those
identified by the maintainer in the referral-by have authoriza-
tion to modify the maintainer. This attribute exists as a means to
clean up should the holder of a maintainer become unresponsive and
can only take effect if that maintainer does not remove the auth-
override in response to the automatic notification that occurs on
changes.
Each repository must identify itself with a ``repository'' object.
The repository must also contain a special ``repository'' whose key
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is ``ROOT''. The root repository is where all non-local queries are
directed, including where hierarchical object queries start. The
query methods listed for the root repository may actually be a subset
of those offered by that repository if efficiency considerations and
topologic distance make some methods less useful.
The root repository must contain a copy of the repository objects
in any repository considered valid. The repository objects will be
essential when the routing registry becomes more widely distributed.
The existing ``mnt-by'' attribute references the ``maintainer'' ob-
ject type. The ``mnt-by'' attribute is now mandatory in all object
types. A new maintainer may be added by any existing maintainer. The
``referral-by'' attribute is now mandatory in the ``maintainer'' ob-
ject to keep a record of which maintainer made the addition and can
never be changed. Maintainers cannot be deleted as long as they are
referenced by a ``referral-by'' attribute elsewhere.
A Examples
The examples below leave out some required attributes that are not
needed to illustrate the use of the objects and attributes described
in this document. Missing are admin-c, tech-c, changed, source. Also
missing are attributes such as mnt-nfy, whose use are a good practice
but are not strictly required.
To do anything at all a maintainer is needed. At some epoch a a sin-
gle maintainer is populated in one repository and that maintianer has
a referal-by pointing to itself. All others referal-by references
can be traced back to that maintainer. At the epoch the as-block AS0-
AS65535 and the inetnum 0.0.0.0-255.255.255.255 are also allocated.
Other ancilliary object may also be needed to bootstrap.
mntner: ROOT-MAINTAINER
auth: pgpkey PGP-12345678
mnt-by: ROOT-MAINTAINER
referal-by: ROOT-MAINTAINER
This root maintainer might add a top level maintainer for some organi-
zation.
mntner: WIZARDS
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descr: High level Technical Folks
auth: pgpkey PGP-23456789
auth: pgpkey PGP-3456789a
mnt-by: WIZARDS
referal-by: ROOT-MAINTAINER
That maintainer might add another who have more limited capabilities.
mntner: MORTALS
descr: Maintain day to day operations
auth: pgpkey PGP-456789ab
auth: pgpkey PGP-56789abc
auth: pgpkey PGP-6789abcd
mnt-by: WIZARDS
referal-by: WIZARDS
Note that the WIZARDS can change their own maintainer object and the
MORTALS maintainer object but MORTALS cannot.
At some point an as-block is allocated and broken down. In the exam-
ple below, private number space is used.
as-block: AS65500-AS65510
mnt-by: SOME-REGISTRY
mnt-lower: WIZARDS
Note that a registry has control over the object that they have cre-
ated representing the allocation, but have given the party to which
the allocation was made the ability to create more specific objects.
Below this as-block, an aut-num is added. Note that import and export
are normally required for a aut-num but are not shown here.
aut-num: AS65501
mnt-by: WIZARDS
mnt-lower: MORTALS
In aut-num above the WIZARDS maintainer can modify the aut-num itself.
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The MORTALS maintainer can add route objects using this AS as the ori-
gin if they also have authorization for the IP number space in a less
specific route or inetnum.
We also need an inetnum allocation. In this example the inetnum is
allocated to a completely different organization. Again attributes
are omited which would normally be needed in an inetnum.
inetnum: 192.168.144.0-192.168.151.255
mnt-by: SOME-REGISTRY
mnt-lower: ISP
reclaim: ALL
The maintainer ISP can add more specific inetnums or routes with this
address space. Note that the registry has declared their ability to
reclaim the address space.
If ISP wished to reclaim all allocations but some suballocation of
theirs resisted, we might get something like the following in which
they will reclaim only the top half of an allocation (possibly if it
remains unused).
inetnum: 192.168.144.0-192.168.147.255
mnt-by: ISP
mnt-lower: EBG-COM
reclaim: 192.168.146/23+
If we assume that the maintainer EBG-COM and the maintainer MORTALS
want to add a route object, one way to do it is for both parties to
sign. If EBG-COM for some reason couldn't aggregate an allocate a
single top level route (which is inexcusable these days) or there was
a preference for some reason to avoid the joint signature approach on
a submission either party could give the other permission to make the
addition. A mnt-routes could be added to the aut-num or a mnt-lower
could be added to an inetnum.
aut-num: AS65501
mnt-by: WIZARDS
mnt-lower: MORTALS
mnt-routes: EBG-COM -192.168.144/23"
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With this change to the aut-num the maintainer EBG-COM could add a
route with origin AS65501, but only with a limited address range.
route: 192.168.144/24
origin: AS65501
descr: These boneheads don't aggregate
mnt-by: EBG-COM
mnt-by: FICTION::MORTALS
Note that while the maintainer EBG-COM added the object they allowed
the maintainer MORTALS the ability to modify it.
If an object ended up in another repository, a single maintainer could
still be used. In the example above the notation FICTION::MORTALS in-
dicates that the route object is in a different repository and rather
than duplicate the maintainer, a reference is made to the repository
in which the MORTALS object resides.
In the example below, a pair of route-sets are added and hierarchical
names are used.
route-set: AS65501:Customers
mnt-by: WIZARDS
mnt-lower: MORTALS
route-set: AS65501:Customers:EBG-COM
mnt-by: MORTALS
mnt-lower: EBG-COM
Suppose in the 192.168.144/24 object above, only the EBG-COM main-
tainer is listed. If EBG-COM goes bankrupt, no longer needs address
space, and stops responding, it could be difficult to delete this
object. The maintainer listed in the EBG-COM referral-by attribute
could be contacted. They could add a auth-override attribute to the
EBG-COM object. Later they could modify the EBG-COM object and then
any objects with EBG-COM in the mnt-by.
mntner: EBG-COM
mnt-by: EBG-COM
auth-override: 19990401
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The examples above stray significantly from realism. They do provide
simple illustrations of the usage of the objects type and attributes
described in this document and hopefully in doing some are of some
value.
B Technical Discussion
A few design tradeoffs exist. Some of these tradeoffs, the selected
solution, and the alternatives are discussed here. Some of the issues
are listed below.
1. Whether to error on the side of permissiveness and weaken autho-
rization controls or risk the possibility of erecting barriers to
registering information.
2. Whether to support enforcible address lending or provide the
smaller or end user with ultimate control over the registration
of the prefixes they are using.
3. What to do with older objects that either don't conform to newer
requirements regarding minimum authorization, authentication, and
accountability, or are of questionable validity.
B.1 Relaxing requirements for ease of registry
If the requirement that an aut-num exists is relaxed, then it is pos-
sible for anyone to make use of an unassigned AS number or make use
of an assigned AS number for which the aut-num has not been entered.
Placing requirements on the entry of aut-num presumes cooperation of
the Internet address allocation authority (if separate from the rout-
ing registry). The address allocation authority must be willing to
field requests to populate skeleton aut-nums from the party for which
the allocation has been made. These aut-num must include a reference
to a maintainer. A request to the address allocation authority must
therefore include a reference to an existing maintainer.
The ability to add route objects is also tied to the existence of less
specific route objects or inetnums. The Internet address allocation
authority (if separate from the routing registry) must also be will-
ing to field requests to add inetnum records for the party already
allocated the address space.
The Internet address allocation authority should also add inetnums and
aut-nums for new allocations. In order to do so, a maintainer must
exist. If a party is going to connect to the Internet, they can get a
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maintainer by making a request to the Internet service provider they
will be connecting to. Once they have a maintainer they can make a
request for address space or an AS number. The maintainer can con-
tain a public key for a cryptographicly strong authorization method
or could contain a ``crypt-key'' or ``mail-to'' authorization check if
that is considered adequate by the registering party. Furthermore an
address allocation authority should verify that the request for an AS
number or for address space matches the authorization criteria in the
maintainer.
Currently only the registry themselves may add maintainers. This be-
comes a problem for the registry particularly verifying public keys.
This requirement is relaxed by allowing existing maintainers to add
maintainers. Unfortunately the accountability trail does not exist
for existing maintainers. The requirement then should be relaxed
such that existing maintainers may remain but only existing maintain-
ers that have a ``referral-by'' attribute can add maintainers. The
``referral-by'' cannot be modified. This requirement can be relax
slightly so that a ``referral-by'' can be added to a maintainer by
an existing maintainer with a ``referral-by''. This will allow the
accountability trail to be added to existing maintainers and these
maintainers can then add new maintainers.
Verifying that a party is who they claim to be on initial addition,
is one of the problems that currently falls upon the AS number and
address registry. This problem is reduced by allowing existing main-
tainers to add maintainers. This may actually make it easier to get
maintainers and therefore easier to register. The number authority
still must verify that the AS or address space is actually needed by
the party making a request.
Authorization checks made during the addition of route objects that
refer to AS objects and inetnum strongly rely on the cooperation of
the Internet address allocation authorities. The number authorities
must register as-blocks, aut-nums, or inetnums as AS numbers or ad-
dress space is allocated. If only a subset of the number authorities
cooperate, then either an inetnum or as-block can be created cover-
ing the space that registry allocates and essentially requiring null
allocation (for example a ``crypt-pw'' authentication where the pass-
word is given in the remarks in the object or its maintainer) or those
obtaining addresses from that number authority will have trouble reg-
istering in the routing registry. The authorization model supports
either option, though it would be preferable if the number authorities
cooperated and the issue never surfaced in practice.
The maintainer requirements can be relaxed slightly for existing main-
tainers making it easier to register. Relaxing requirements on other
objects may defeat the authorization model, hence is not an option.
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B.2 The address lending issue
The issue of whether lending contracts should be enforcible is an
issue of who should ultimately be able to exercise control over al-
locations of address space. The routing registry would be wise to
stay as neutral as possible with regard to disputes between third par-
ties. The ``reclaim'' and ``no-reclaim'' are designed to allow either
outcome to the decision as to whether the holder of a less specific
inetnum or route object can exercise control over suballocations in
the registry. The routing registry itself must decide whether to re-
tain control themselves and if so, should very clearly state under
what conditions the registry would intervene. A registry could even
go to the extreme of stating that they will intervene in such a dis-
pute only after the dispute has been resolved in court and a court
order has been issued.
When an allocation is made by a registry, the registry should keep a
``reclaim'' attribute in the less specific object and make a strong
policy statement that the reclaim privilege will not be used except
under very clearly defined special circumstances (which at the very
minimum would include a court order). If the allocation is further
subdivided the party subdividing the allocation and the party accept-
ing the suballocation must decide whether a ``reclaim'' can be kept by
the holder of the less specific allocation or whether a ``no-reclaim''
must be added transferring control to the holder of the more specific.
The registry is not involved in that decision. Different pairs of
third parties may do different decisions regarding the ``reclaim''
and any contractual restrictions on its use that may be expressed out-
side of the registry in the form of a legal contract and ultimately
resolved by the courts in the event of a bitter dispute.
By retaining ``reclaim'' rights the registry retains the ability to
abide by a court order. This may only truly become an issue in a dis-
tributed registry environment where registries will be rechecking the
authorization of transactions made elsewhere and may fail to process
the attempt of another registry to abide by a court order by overrid-
ing normal authorization to change the registry contents if a reclaim
is not present.
B.3 Dealing with non-conformant or questionable older data
Some of the newer requirements include requiring that all objects
reference a maintainer object responsible for the integrity of the
object and requiring accountability for the creation of maintainers
to be recorded in the maintainer objects so that accountability can
be traced back from an unresponsive maintainer. In the event that
contact information is absent or incorrect from objects and there is
any question regarding the validity of the objects, the maintainer can
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be contacted. If the maintainer is unresponsive, the maintainer that
authorized the addition of that maintainer can be contacted to either
update the contact information on the maintainer or confirm that the
entity no longer exists or is no longer actively using the Internet or
the registry.
Many route objects exist for which there are no maintainers and for
which inetnum and AS objects do not exist. Some contain the now obso-
leted guardian attribute rather than a mnt-by.
It is not practical to unconditionally purge old data that does not
have maintainers or does not conform to the authorization hierarchy.
New additions must be required to conform to the new requirements
(otherwise the requirements are meaningless). New requirements can
be phased in by requiring modifications to conform to the new require-
ments.
A great deal of questionable data exists in the current registry. The
requirement that all objects have maintainers and the requirements
for improved accountability in the maintainers themselves may make it
easier to determine contact information even where the objects are not
updated to reflect contact information changes.
It is not unreasonable to require valid contact information on exist-
ing data. A great deal of data appears to be unused, such as route
objects for which no announcement has been seen in many months or
years. An attempt should be made to contact the listed contacts in
the object, in the maintainer if there is one, then up the maintainer
referral-by chain if there is one, and using the number registry or
origin AS contact information if there is no maintainer accountability
trail to follow. Experience so far indicates that the vast majority
of deletions identified by comparing registered prefixes against route
dumps will be positively confirmed (allowing the deletion) or there
will be no response due to invalid contact information (in many cases
the IRR contact information points to nsfnet-admin@merit.edu).
By allowing the registry to modify (or delete) any objects which are
disconnected from the maintainer accountability trail, cleanup can
be made possible (though mail header forging could in many cases have
the same effect it is preferable to record the fact that the registry
itself made the cleanup). Similarly, a mechanism may be needed in
the future to allow the maintainer in the referral-by to override
maintainer privileges in a referred maintainer if all contacts have
become unresponsive for a maintainer. The referral-by maintainer is
allowed to add an ``auth-override'' attribute which becomes usable
as an ``auth'' within 60 days from the time of addition. The main-
tainer themselves would be notified of the change and could remove the
``auth-override'' attribute before it becomes effective and inquire as
to why it was added and correct whatever problem existed. This can be
supported immediately or added later if needed.
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C Common Operational Cases
In principle address allocation and route allocation should be hierar-
chical with the hierarchy corresponding to the physical topology. In
practice this is often not the case for numerous reasons. The pri-
mary reasons are the topology is not strictly tree structured and the
topology can change. More specificly:
1. The Internet topology is not strictly tree structured.
o At the top level the network more closely resembles a moderately
dense mesh.
o Near the bottom level many attachments to the Internet are multi-
homed to more than one Internet provider.
2. The Internet topology can and does change.
o Many attachments switch providers to obtain better service or
terms.
o Service providers may modify adjacencies to obtain better transit
service or terms.
o Service providers may disappear completely scattering attachments
or merge.
Renumbering is viewed as a practical means to maintain a strict nu-
meric hierarchy [18]. It is also acknowledged that renumbering IPv4
networks can be difficult [18, 3, 19 ]. We examine first the simple
case where hierarchy still exists. We then examine the operational
cases where either initial topology is not tree structured or cases
where topology changes.
C.1 simple hierarchical address allocation and route allocation
This is the simplest case. Large ranges of inetnums are assigned to
address registries. These registries in turn assign smaller ranges
for direct use or to topologically large entities where allocations
according to topology can reduce the amount of routing information
needed (promote better route aggregation).
AS objects are allocated as topology dictates the need for additional
AS [10]. Route objects can be registered by those with authoriza-
tion given by the AS and by the address owner. This is never an issue
where the maintainer of the AS and the inetnum are the same. Where
they differ, either the provider can give permission to add route ob-
jects for their AS, or the party allocated the address space can give
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the provider permission to add router objects for their address space,
or both parties can sign the transaction. Permission is provided by
adding to maintainer attributes.
C.2 aggregation and multihomed more specific routes
Aggregation is normally not a problem if a provider is aggregating ad-
dress space allocated to the provider and then suballocated internally
and/or to customers. In fact, the provider would be expected to do
so. This is not a problem even if the route object for the aggrega-
tion is added after the more specific route objects since only less
specific objects are considered.
Aggregation is potentially a problem if a provider or a set of
providers plan to aggregate address space that was never explicitly
allocated as a block to those providers but rather remains the alloca-
tion of a address registry. These large aggregations can be expected
to be uncommon, but relatively easily dealt with. Superaggregates of
this type will generally be formed by topologically close entities who
have also managed to draw adjacent address allocations. In effect,
the registry must give permission to form such as superaggregate by
either giving permission to do so in the mnt-routes of an inetnum or
by signing the submission along with the other parties.
C.3 provider independent addresses and multiple origin AS
Provider independent addresses and multihoming arrangement using mul-
tiple origin AS present a similar problem to multihoming. The main-
tainer of the address space and the maintainer of the AS is not the
same. Permission can be granted using mnt-routes or multiple signa-
tures can appear on the submission.
C.4 change in Internet service provider
A change in Internet service providers is similar to multihoming.
A minor difference is that the AS for the more specific route will
be the AS of the new provider rather than the AS of the multihomed
customer. Permission can be granted using mnt-routes or multiple
signatures can appear on the submission.
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C.5 renumbering grace periods
Renumbering grace periods allow a provider who wants to keep an ad-
dress allocation intact to allow a customer who has chosen to go to
another provider to renumber their network gradually and then re-
turn the address space after renumbering is completed. The issue of
whether to require immediate renumbering or offer renumbering grace
periods and how long they should be or whether they should be in-
definite has been topic of bitter disputes. The authorization model
can support no renumbering grace period, a finite renumbering grace
period, or an indefinite renumbering grace period. The ``reclaim''
attribute described in Section 9.1 provides a means to end the grace
period.
D Deployment Considerations
This section describes deployment considerations. The intention is to
raise issues and discuss approaches rather than to provide a deploy-
ment plan.
The use of routing registries is not yet universally accepted. There
still remain Internet providers who see no reason to provide the added
assurance of accurate routing information described in Section 6.
More accurately, these benefits are viewed as being insufficient to
justify the cost. This has been largely caused an inability of a very
major router vendor up until recently to handle prefix lists of the
size needed to specify routing policy on a per prefix basis. Another
reason cited is that filtering on a prefix basis in an environment
where routing registry is incomplete or inaccurate can interfere with
connectivity.
There clearly is a critical mass issue with regard to the use of rout-
ing registries. A minority of providers use the existing IRR to
filter on a per prefix basis. Another minority of providers do not
support the IRR and generally fail to register prefixes until con-
nectivity problems are reported. The majority of providers register
prefixes but do not implement strict prefix filtering.
Deploying new authentication mechanisms has no adverse consequences.
This has been proven with Merit's deployment of PGP.
In deploying new authorization mechanisms, a major issue is dealing
with existing data of very questionable origin. A very large num-
ber of route objects refer to prefixes that have not been announced
for many years. Other route objects refer to prefixes that are no
longer announced with the origin AS that they are register with (some
were incorrectly registered to start with). There are many causes for
this.
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1. During the transition from the NSFNET PRDB to the RADB a large
number of prefixes were registered with an origin AS correspond-
ing to the border AS at which the NSFNET had once heard the route
announcements. The PRDB did not support origin AS, so border
AS was used. Many of these routes were no longer in use at the
time and are now routed with a submitter listed as ``nsfnet-
admin@merit.edu''.
2. As CIDR was deployed, aggregates replaced previously separately
announced more specific prefixes. The route objects for the more
specific prefixes were never withdrawn from the routing registries.
3. Some prefixes are simply no longer in use. Some networks have been
renumbered. Some network no longer exist. Often the routing reg-
istry information is not withdrawn.
4. As provider AS adjacencies changed and as end customers switched
providers often the actual origin AS changed. This was often not
reflected by a change in the routing registry.
Inaccuracies will continue to occur due to the reasons above, except
the first. The hierarchical authorization provides greater account-
ability. In the event that the contacts for specific objects become
unresponsive traversal up the authorization hierarchy should help
identify the parties having previous provided authorization. These
contacts may still have sufficient authorization to perform the neces-
sary cleanup. This issue is discussed in Section B.
A great deal of information is currently missing in the IRR. Quite a
few AS have no aut-num. Quite a lot of data has no maintainer and the
vast majority of maintainers use only the weakest of authentication
methods. Very little can be done by the registries to correct this.
The defaults in the cases of missing objects needed for authorization
has to be to make no authentication checks at all.
The transition can be staged as follows:
1. Add and make use of stronger authorization models.
2. Make schema modifications necessary to support delegations.
3. Add delegation objects needed for query traversal.
4. Base query traversal on delegations rather than search of all known
registries.
5. Obtain the cooperation of the address registries for the purpose of
populating the ``inetnum'' entries on an ongoing basis.
6. Add hierarchical authorization support for critical object types,
``aut-num'', ``inetnum'' and ``route''.
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7. Add the requirement that database object either be in use or have
valid contact information and if queries are made by the registry a
response from a contact indicating that the object serves a purpose
if it is not clear what its use is.
8. Begin to purge data which is clearly not in use and for which there
is no valid contact information or no response from the contacts.
Deployment of hierarchical authorization requires cooperation among
the existing routing registries. New code will have to be deployed.
In some cases very little development resources are available and sub-
stantial inertia exists due to the reliance on the current repository
and the need to avoid disruption.
If hierarchical authorization of route objects depends on the exis-
tence of address registration information, minimal cooperation of
the currently separate address registries is required. The extent
of the cooperation amounts to sending cryptographically signed trans-
actions from the address registry to the number registry as address
allocations are made or providing equivalent access to new address
allocations.
Currently most registries returns query results from all of the known
repositories using their mirrored copies. Cross registry authoriza-
tions are not yet implemented. Minimal schema changes have to be made
to support the ability to delegate objects for which there is an au-
thorization hierarchy and the support queries and references to other
repositories. In the case of AS delegations, ``as-block'' need to be
created solely for the purpose of traversal.
E Route Object Authorization Pseudocode
The following list provides a brief review of basic concepts.
1. The route object submission must satisfy two authentication cri-
teria. It must match the authentication specified in the aut-num
and the authentication specified in either a route object or if no
applicable route object is found, then an inetnum.
2. When checking for prefix authorization, an exact route object pre-
fix match is checked for first. If there is not an exact match
then a longest prefix match that is less specific than the prefix
is searched for. If the route prefix search fails, then a search
is performed for an inetnum that exactly matches the prefix or for
the most specific inetnum that is less specific than the route ob-
ject submission.
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The search for an inetnum should never fail but it may return an
unallocated or reserved range. The inetnum status must be ``allo-
cated'' and the submission must pass it's maintainer authorization
in order to get authorization from an inetnum. So an unallocated
or reserved range inetnum will cause the route object submission to
fail.
3. A route object must pass authorization from both the referenced
aut-num object and the route or inetnum object.
Authorization shall be tested using the maintainer(s) referenced
in the ``mnt-routes'' attribute(s) first. If that check fails,
the ``mnt-lower'' attributes are checked. If that check fails the
``mnt-by'' attributes are used for the authorization check.
4. The ``reclaim'' attribute can appear in inetnum, route and as-block
objects and provides a means to support address lending. ``re-
claim'' gives authorization over more specific objects, regardless
of the ``mnt-by'' in the object. The value of a ``reclaim'' at-
tribute can be a list or set of objects to provide finer grain
control.
The ``reclaim'' attribute is important to this discussion since
it affects prefix/origin authentication when a new route object is
submitted.
The ``no-reclaim'' attribute is used to provide explicit excep-
tions.
The following pseudocode outlines the algorithm used to check for
proper authorization of a route object submission.
Case #1. Route object add
(ie, no exact prefix/origin match exists).
/* first check the aut-num authorization */
if ( the referenced aut-num object does not exist or
the aut-num authorization fails )
authorization fails
/* next we check for prefix authorization */
if ( a less specific route(s) with the longest prefix is found ) [
if ( authorization does not pass for at least one of the less
specific route(s) )
authorization fails
/* now check for a "reclaim" attr */
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if ( the object has a "reclaim" attribute ) [
if ( no more-specifics exist
OR a less specific exists which passes
authorization and has a "reclaim" attribute
OR all more specifics routess pass modify authorization )
authorization passes
else
authorization fails
] else
authorization passes
]
/* there are no less specific routes to check for prefix
authentication, so we need to try and get authorization from an
inetnum object */
if ( ( an inetnum is found that is an exact match
OR is less specific and it's status is "allocated" )
AND a maintainer referenced by the inetnum
passes authorization )
authorization succeeds
/* if there is no inetnum or route object then then
authorization fails. This should never happen if
the DB is initialized properly. */
authorization fails.
Case #2. Route object modify/delete
(ie, exact prefix/origin match exists).
if ( the mnt-by passes authorization )
authorization succeeds
/* if the authorization did not pass from the matched object,
we can still get authorization from a less specific route if it
has a "reclaim" attribute and we pass authorization */
if ( a less specific route or inetnum object passes authorization
AND has a "reclaim" attribute applicable to
the object to be modified )
authorization succeeds
else
authorization fails
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Acknowledgments
This document draws ideas from numerous discussions and contributions
of the IETF Routing Policy System Work Group and RIPE Routing Work
Group. Earlier drafts of this document listed Carol Orange as a co-
author. Carol Orange made contributions to this document while at
RIPE.
Gerald Winters provided the pseudocode in an email message to the
RIPE dbsec mailing list that was the basis of the pseudocode found in
appendix E.
References
[1] C. Alaettinoglu, T. Bates, E. Gerich, D. Karrenberg, D. Meyer,
M. Terpstra, and C. Villamizar. Routing policy specification
language (rpsl). Technical Report RFC 2280, Internet Engineering
Task Force, 1998. ftp://ftp.isi.edu/in-notes/rfc2280.txt.
[2] T. Bates, E. Gerich, L. Joncheray, J-M. Jouanigot, D. Kar-
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ing policies in a routing registry (ripe-81++). Techni-
cal Report RFC 1786, Internet Engineering Task Force, 1995.
ftp://ftp.isi.edu/in-notes/rfc1786.txt.
[3] H. Berkowitz. Router renumbering guide. Technical Re-
port RFC 2072, Internet Engineering Task Force, 1997.
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[4] H.W. Braun. Models of policy based routing. Technical
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[5] H.W. Braun and Y. Rekhter. Advancing the nsfnet routing archi-
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routing (cidr): an address assignment and aggregation strat-
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[9] Internet Engineering Steering Group and R. Hinden. Applicability
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[10] J. Hawkinson and T. Bates. Guidelines for creation, selec-
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[12] M. Knopper and S. Richardson. Aggregation support in the nsfnet
policy-based routing database. Technical Report RFC 1482, In-
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notes/rfc1482.txt.
[13] David Meyer, Mark Prior, Cengiz Alaettinoglu, J. Schmitz, and
Carol Orange. Using rpsl in practice. Internet Draft (Work in
Progress) draft-ietf-rps-appl-rpsl-04, Internet Engineering Task
Force, 2 1999. ftp://ftp.isi.edu/internet-drafts/draft-ietf-rps-
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authent-00.txt.
Security Considerations
This document primarily addresses authorization rules for making ad-
ditions, deletions, and changes to routing policy information repos-
itories. The authentication of these transactions through strong
cryptographic means are addressed by [21], referenced thorughout this
document. The authorization rules are designed such that the inte-
grety of any transaction can be verified independently by any party
mirroring a repository to insure that rules are adhered to. To accom-
plish this the mirror must contain data already known to be properly
authorized. In other words, the mirror must be complete and authenti-
cation and authorization checks must be made continuously as changes
to the repository are recieved and processed in order.
Authentication alone does not provide a complete security model. Cur-
rent practice specifies authorization for deletions and changes only,
not for additions. The authorization rules provide here complete
the security model for additions, deletions, and changes by very ex-
plicitly defining rules for addition and clarifying procedures for
handling exception cases such as organizations which have ceased to
exist and therefore become entirely unresponsive.
Authentication and authorization of queries is explicitly stated to be
out of scope of this document.
Author's Addresses
Curtis Villamizar
UUNET Network Architecture Group
<curtis@ans.net>
Cengiz Alaettinoglu
ISI
<cengiz@ISI.EDU>
David M. Meyer
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Cisco
<dmm@cisco.com>
Sandy Murphy
Trusted Information Systems
<sandy@tis.com>
Full Copyright Statement
Copyright (C) The Internet Society (April 22, 1999). All Rights Re-
served.
This document and translations of it may be copied and furnished to
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provided that the above copyright notice and this paragraph are in-
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copyright notice or references to the Internet Society or other In-
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Villamizar, et. al. Expires October 22, 1999 [Page 40]
