Int. J. Communications, Network and System Sciences, 2009, 7, 641-644
doi:10.4236/ijcns.2009.27072 Published Online October 2009 (
Copyright © 2009 SciRes. IJCNS
An Identifier-Based Network Access Control Mechanism
Based on Locator/Identifier Split
Rui TU1, Jinshu SU1, Ruoshan KONG2
1School of Computer Science, National University of Defense Technology, Changsha, China.
2International School of Software, Wuhan University, Wuhan, China
Received January 5, 2009; revised May 15, 2009; accepted July 12, 200 9
Legacy IP address-based access control has met many challenges, because the network nodes cannot be
identified accurately based on their variable IP addresses. “Locator/Identifier Split” has made it possible to
build a network access control mechanism based on the permanent identifier. With the support of “Loca-
tor/Identifier Split” routing and addressing concept, the Identifier-based Access Control (IBAC) makes net-
work access control more accurate and efficient, and fits for mobile nodes’ access control quite well. More-
over, Self-verifying Identifier makes it possible for the receiver to verify the packet sender’s identity without
the third part authentication, which greatly reduces the probability of “Identifier Spoofing”.
Keywords: Access Control, Locator/Identifier Split, IBAC, Self-Verifying Identifier, Identifier Spoofing
1. Introduction
In the current TCP/IP architecture, IP address has dual
semantic functions, which indicates both the network
node’s routing locator and its endpoint identifier [1]. It
means that the IP address is a variable label related to the
location. Because of the “IP Overload” [1], IP address-
based access control has met many challenges.
Firstly, IP address-based access control limits the re-
source access when a node changes its location. Network
services often distinguish users by their IP addresses, so
many services are bound with the clients’ locations. As a
result, when a user of an authorized organization moves
to another location (and so the IP address is changed.),
he will lose the access ability of the service.
Secondly, “IP Overload” makes IP address-based ac-
cess control even more complex, and greatly affects its
defense efficiency:
1) Because IP address is a variable label, it can’t be
used as an accurate identifier of the nodes. Moreover, “IP
Spoofing” has made it even more critical. So it is diffi-
cult to identify the access source in the network layer,
and the attackers can anonymously attack the network
devices and services.
2) IP address can’t match users precisely [2]. One IP
address can represent different nodes at different time.
On the other hand, one IP address can also represent
multiple nodes simultaneously (e.g. NAT). As a result,
the attacker can hide his true identity easily.
For the above reasons, the efficiency of IP ad-
dress-based access control is greatly declined, and some
misuses will harm the valid users.
Finally, the changes of the network topology and the
ISP policies will lead to the reconfiguration of the IP
addresses. Thus, many access control rules and configu-
rations based on IP addresses have to be modified. Un-
doubtedly, this will make the access control management
more c omplex.
The reason of the above drawbacks lies in that there is
no accurate, unique and permanent identifier to describe
a network node. So the key problem is to r esolve the “IP
Overload” problem. IAB announced that in order to re-
solve the “IP Overload”, two name spaces should be in-
troduced to denote a network node’s locator and identi-
fier separately, which is called “Locator/Identifier Split”
[3]. The communication session is based on the perma-
nent Identifier, and the routing is based on the variable
In this paper, we propose LISA Network Access Con-
trol (LISA-NAC) which is a new network access control
mechanism based on the Locator Identifier Separation
Architecture (LISA) [4]. The main contributions of
LISA-NAC are the Identifier Based Access Control
(IBAC) model and the Self-Verifying Identifier, which
will make network access control more efficient.
The rest of this paper is organized as follows. Section
2 presents an Overview of LISA Architecture. Section 3
describes some new characters of LISA-NAC, including
IBAC model and Self-Verifying Identifier. Section 4
gives an outline of our future work. Finally, we conclude
with a summary of the main research result in Section 5.
2. LISA Overview
LISA is a network-based “Locator/Identifier Split” nam-
ing and addressing architecture, which borrowed come
ideas of LISP [5]. As Figure 1 shows, the network is di-
vided into two parts: kernel network and edge network.
The kernel network uses Locator name space, while the
edge network uses permanent Identifier name space. The
communication session is built on permanent Identifier,
but the mapped Locator is variable.
LISA adopts “Mapping + Encapsulation” method to
process packets. LISA Router (Edge router) maps the
Identifier space into Locator space by querying distrib-
uted mapping service system based on one-hop hash
(LISA-Mapping). Moreover, LISA Router can update the
mapping record in the LISA-Mapping. The Identifier
space is a new name space (see Subsection 3.2). The
Locator space can reuse the legacy IP address space
(IPv4/v6), which will avoid updating network devices in
the kernel network.
When a LISA Route receives the packet from host, it
queries the LISA-Mapping for the matched Locator ac-
cording to the packet’s Identifier. After receiving the
mapped Locator, the LISA Router adds a new packet
header (including the Locator) to the original packet. So
in the encapsulated packet, the inner address is an Identi-
fier, and the outer address is a Locator. LISA uses Iden-
tifier to denote the node identity, and uses Locator to
forward packet in the kernel network. When the encap-
sulated packet arrives at the destination (the LISA
Router), the LISA Router decapsulates the packet, and
forwards the original packet to the destination host ac-
cording to the Identifier.
In order to improve the efficiency of network access
control, network accountability should be mentioned.
Network accountability is the capability to identify net-
work entity (user, host and device) and distinguish mal-
traffic. However, limited by the “dumb” network infra-
structure, it is difficult to achieve accountability in the
Internet. There is no accurate, unique and permanent
identifier to identify network entity. IP header is too
simple, more state information (e.g. identifier) should be
added to satisfy the needs of security, QoS and network
In the LISA, LISA-NAC runs on the permanent Iden-
tifier name space, and provides an accurate and efficient
fine-grained access control mechanism for the edge net-
work. The main features of LISA-NAC are the IBAC
model and the Self-Verifying Identifier.
3.1. IBAC Model
Different from the traditional network access control,
IBAC makes access control policies based on the net-
work node’s true permanent Identifier, not IP address or
device port.
IBAC includes three entities: Identifier (I), Object (O)
and Permission (P). There are two types of Identifiers:
Individual Identifier (I2) and Identifier Affiliation (IA).
Figure 1. LISA architecture.
Copyright © 2009 SciRes. IJCNS
R. TU ET AL. 643
I2 denotes the single network node, and IA denotes a
group of network nod es.
IBAC uses three-tuple (I, O, P) to describe an author-
ity. If there exists a (I, O, P), it indicates that I can per-
form P on the O. Particularly, (I2, O, P) indicates that
single I can perform P on the O, and (IA, O, P) indicates
that a group of I can perform P on the O.
IBAC provides end to end security mechanism and
fine-grained access control. For example, if several users
share a locator (e.g. IP address), IBAC can make inde-
pendent security policy for everyon e. In order to simplify
the format of the access control policy and reduce the
ACL’s size, IBAC uses the IA to classify Identifiers, and
adopts unified operation on the Identifiers which have
the same IA. IA is not directly in the packet header, and
is stored in the LISA-Mapping system. The destination
should query the LISA-Mapping system for the matched
IBAC guarantees the access control policy’s long term
stability. Although the network entities’ Locators are
variable, the access control policies based on the perma-
nent Identifier are unchanged, so the valid users can al-
ways use their services. So IBAC can fit for the mobile
node’s access control. IBAC avoids the policy updates
due to the Locators’ changes, and greatly reduces the
workload of maintaining the access control policy.
In current network, in order to achieve end to end au-
thority control, network access control should collaborate
with the access control mechanisms of the system or ap-
plication software. Since IBAC guarantees the end to end
access control and provides network accountability, it is
possible to simplify the upper layer’s access control. If
the Identifier can be combined with the user’s biology
properties in the future, the network will be aware of the
user’s identity and behaviors, and thus no more needs of
user’s accounts and passwords.
3.2. Self-Verifying Identifier
True Identifier is the basis of IBAC. Similarly, IBAC
also meets the potential threat of “Identifier Spoofing”.
So we introduce “Self-verifying Identifier” in the LISA-
NAC. With Self-verifying Identifier, the receiver can
verify the sender’s identity based on the packet’s Iden-
tifier without the participation of third part authentica-
In the LISA, every network node gets a pair of asym-
metry keys from the CA. The node holds the private key,
and makes the public key as the node’s globe unique
identifier. In other words, the identifier name space is a
public key space. LISA-NAC ensures the consistency
between the Identifier and th e nod e’s id entity th ro ugh the
digital signature mechanism.
Self-verifying Identifier simplifies packet’s source
Identifier verification, and strengthen the scalability be-
cause there is no need for the third part authentication. At
present, we adopt 1 60 -bit Self-verifying Identifier.
Since the Identifier is actually a public key, we should
choose an appropriate asymmetry keys generation algo-
rithm. Traditional asymmetry keys algorithms such as
RSA, DSA and Diffie-Hellman often choose long keys to
guarantee the key’s safety. For example, a normal RSA
key is 1024-bit. However, such long key is unfit for the
Identifier. Firstly, long identifier increases the packet’s
size, which may lead to packet fragment and consumes
additional bandwidth. On the other hand, since 128-bit
Identifier space is enough for current IPv6 network size,
it is useless to make a huge Identifier name space.
In the LISA-NAC, we use ECC (Elliptic curve cryp-
tography) algorithm to create a pair of 160-bit asymme-
try keys for every network node. ECC’s advantages lie
1) ECC offers security equivalent to RSA using much
smaller key size. For example, ECC 160-bit key offers
security equivalent to RSA 1024-bit key [6]. This prop-
erty will reduce the engineering challenges brought by
long key.
2) ECC generates asymmetry keys pair faster than
RSA does for the comparable length [7 ]. Considering the
signature generation and verification, ECC’s processing
speed is much faster than that of RSA [8]. This makes it
possible to implement packet digital signature verifica-
tion with limited packet delay.
At present, 109-bit ECC key has knocked over with
brute force. However, the secure 160-bit ECC key is ap-
proximately one hundred million times harder to crack
than 109-bit ECC key [9]. So we think that 160-bit ECC
key can fit the Identifier length, as well as satisfy the
basic security requirements.
Figure 2 shows the verification process of Self-veri-
fying Identifier. IDs and IDd denote the packet’s source
and destination Identifier separately. In fact, IDs and IDd
are the sender and receiver’s public key. Dig is the
packet’s digest. Sig is the digital signature. The receiver
identifies the true sender though verifying packet’s sig-
If an attacker disguises as the sender and sends a
packet, he must have the sender’s private key to generate
Figure 2. Self-verifying identifier verification.
Copyright © 2009 SciRes. IJCNS
Copyright © 2009 SciRes. IJCNS
the correct encrypted signature. Since the attacker
doesn’t have the sender’s private key, when the receiver
generates a new packet digest (Dig’), it must be different
from the decrypted original packet digest (Dig). So the
“Identifier Spoofing” can be detected.
The packet carries the public key, and there is no key
exchange during the node identity verification. Obvi-
ously, it will simplify the identity verification process.
Since network access control is deployed to protect the
important services, it is unnecessary to include signature
verification in the general packet processing. Most of the
network nodes can choose the packet signature verifica-
tion as an option, but the packet signature is imperative.
Moreover, a node can publish its Iden tifier to the DNS so
that all the other nodes can get its public key to encrypt
4. Future Work
In the LISA-NAC, verifying signature on every packet
will undoubtedly add packet delay. The transmission
performance degradation is what we are concerning
about. A prototype is under development, and we will
measure the main transmission performance (delay, loss
and throughput) changes to test the feasibility of LISA-
At present, Identifier only indicates the network
node’s property not including the user’s property. Next
step, we will try to combine the Identifier with th e user’s
biology properties. Then the network will be aware of
users’ identity and behaviors.
5. Conclusions
LISA separates the network node’s identity from location,
which makes it possible to build a network access control
mechanism based on the identifier. IBAC makes network
access control more accurate and efficient. Moreover,
IBAC fits for the mobile node’s access control. Since
true Identifier is the basis of IBAC, “Identifier Spoofing”
must be avoided. Self-verifying Identifier makes it pos-
sible for the receiver to verify packet sender’s identity
without the third part auth enticatio n , which si mplifies the
packet source verification. We think that LISA-NAC is a
concrete step to strengthen network security through the
“Locator/Identifier Split”.
6. Acknowledgements
This work was supported by China “863” Project (No.
2008AA01A325) and China National Grand Fundamen-
tal Research “973” Project (No. 2009CB320503).
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