R_RFC2406_3_4_3 - [Responder Test] Sequence Number Verification
End-Node
R_RFC2406_3_4_3.seq [-tooloption ...] -pkt R_RFC2406_3_4_3.def -tooloption : v6eval tool option
See also ike_common.def and ike_ipsec.def and ike_pkt_ph1_recv.def and ike_pkt_ph2_recv.def
HOST-2(TN):initiator
|3ffe:501:ffff:101::11
|
Net-y --+--------+------------------------ 3ffe:501:ffff:101::/64
|
|
ROUTER-1(TN)
|3ffe:501:ffff:100::11
|
Net-z --+--------+------------------------ 3ffe:501:ffff:100::/64
|
|3ffe:501:ffff:100:XXXX
NUT:responder
XXXX: EUI64 address
Verification Points
Encapsulating Security Protocol Processing(Inbound Packet Processing)
Sequence Number
If the receiver has enabled the anti-replay service for this SA, the
receive packet counter for the SA MUST be initialized to zero when
the SA is established. For each received packet, the receiver MUST
verify that the packet contains a Sequence Number that does not
duplicate the Sequence Number of any other packets received during
the life of this SA. This SHOULD be the first ESP check applied to a
packet after it has been matched to an SA, to speed rejection of
duplicate packets.
Configuration
Initiator and Responder IKE parameter
At least, following parameter must be included in proposal.
| Machine |
Src |
Dest |
Phase I |
Phase II |
| Ex mode |
Key Value |
Enc Alg |
Hash Alg |
Auth Method |
DH Group |
PH1 Lt |
IDx |
Proto ID |
Trans ID |
Mode |
Auth Alg |
PH2 Lt |
Upper |
| NUT |
NUT addr |
HOST-2 addr |
Main |
IKE-TEST |
3DES |
SHA |
pre-shared key |
2 |
8 Hour |
NUT addr |
PROTO_IPSEC_ESP |
ESP_3DES |
Transport |
HMAC-SHA |
8 Hour |
any |
| HOST-2 |
HOST-2 addr |
NUT addr |
Main |
IKE-TEST |
3DES |
SHA |
pre-shared key |
2 |
8 Hour |
HOST-2 addr |
PROTO_IPSEC_ESP |
ESP_3DES |
Transport |
HMAC-SHA |
8 Hour |
any |
*Ex Mode = Exchange mode(Aggresive mode can also be chosen as Ex Mode)
*IDx = identity payload(FQDN or user FQDN can also be chosen as IDx)
*Enc Alg = IKE Encryption Algorithm
*Hash Alg = IKE Authentication Algorithm
*Key Value = pre-shared key value
*PH1 Lt = Phase-1 Lifetime
*PH2 Lt = Phase-2 Lifetime
*Proto ID = Protocol Identifier
*Trans ID = Transform Identifier
*Mode = Encapsulation Mode
*Auth Alg = Authentication Algorithm
*Auth Method = Authentication Method
*DH Group = Diffie-Hellman Group
*Upper = Upper Layer Protocol
*NUT addr = NUT address
*HOST-2 addr = HOST-2 address
This test check is following.
* PHASE I
Either IDENTITY PROTECTION EXCHANGE or AGGRESSIVE EXCHANGE is performed as a pre sequence.
IDENTITY PROTECTION EXCHANGE
# Initiator(TN) Direction Responder(NUT)
(1) HDR; SA ========>
(2) <======== HDR; SA
(3) HDR; KE; NONCE ========>
(4) <======== HDR; KE; NONCE
(5) HDR*; IDii; HASH_I ========>
(6) <======== HDR*; IDir; HASH_R
1. Send the first message from TN
In the first message (1), the initiator generates a proposal it
considers adequate to protect traffic for the given situation. The
Security Association, Proposal, and Transform payloads are included
in the Security Association payload (for notation purposes).
2. Receive the second message from NUT
In the second message (2), the responder indicates the protection
suite it has accepted with the Security Association, Proposal, and
Transform payloads.
3. Send the third message from TN
In the third (3) message, the initiator send keying material
used to arrive at a common shared secret and random information
which is used to guarantee liveness and protect against replay attacks.
4. Receive the fourth message from NUT
In the fourth (4) message, the responder send keying material
used to arrive at a common shared secret and random information
which is used to guarantee liveness and protect against replay attacks.
5. Send the fifth message from TN
In the fifth (5) message, the initiator send identification
information and the results of the agreed upon authentication
function(hash function).
6. Receive the sixth message from NUT
In the sixth (6) message, the responder send identification
information and the results of the agreed upon authentication
function(hash function).
AGGRESSIVE EXCHANGE
# Initiator(TN) Direction Responder(NUT) NOTE
(1) HDR; SA; KE; => Begin ISAKMP-SA or
Proxy negotiation
NONCE; IDii and Key Exchange
(2) <= HDR; SA; KE;
NONCE; IDir; AUTH
Initiator Identity
Verified by Responder
Key Generated
Basic SA agreed upon
(3) HDR*; AUTH =>
Responder Identity
Verified by Initiator
SA established
1. Send the first message from TN
In the first message (1), the initiator generates a proposal it
considers adequate to protect traffic for the given situation. The
Security Association, Proposal, and Transform payloads are included
in the Security Association payload (for notation purposes). There
can be only one Proposal and one Transform offered (i.e. no choices)
in order for the aggressive exchange to work. Keying material used
to arrive at a common shared secret and random information which is
used to guarantee liveness and protect against replay attacks are
also transmitted. Random information provided by both parties SHOULD
be used by the authentication mechanism to provide shared proof of
participation in the exchange. Additionally, the initiator transmits
identification information.
2. Recieve the second message from NUT
In the second message (2), the responder indicates the protection
suite it has accepted with the Security Association, Proposal, and
Transform payloads. Keying material used to arrive at a common
shared secret and random information which is used to guarantee
liveness and protect against replay attacks is also transmitted.
Random information provided by both parties SHOULD be used by the
authentication mechanism to provide shared proof of participation in
the exchange. Additionally, the responder transmits identification
information. All of this information is transmitted under the
protection of the agreed upon authentication function. Local
security policy dictates the action of the responder if no proposed
protection suite is accepted. One possible action is the
transmission of a Notify payload as part of an Informational
Exchange.
3. Send the third message from TN
In the third (3) message, the initiator transmits the results of the
agreed upon authentication function. This information is transmitted
under the protection of the common shared secret. Local security
policy dictates the action if an error occurs during these messages.
One possible action is the transmission of a Notify payload as part
of an Informational Exchange.
* PHASE II
QUICK MODE
# Initiator(TN) Direction Responder(NUT)
(1) HDR*, HASH(1),
SA, Ni ========>
(2) <======== HDR*, HASH(2), SA, Nr
(3) HDR*, HASH(3) ========>
1. Send the first message from TN
In the first message (1), the initiator generates a proposal it
considers adequate to protect traffic for the given situation. The
Security Association, Proposal, and Transform payloads are included
in the Security Association payload (for notation purposes).
And initiator send HASH(1) and Nonce. HASH(1) is the prf over the
message id (M-ID) from the ISAKMP header concatenated with the entire
message that follows the hash including all payload headers,
but excluding any padding added for encryption. Nonce is random
information which is used to guarantee liveness.
2. Receive the second message from NUT
In the second message (2), the responder indicates the protection
suite it has accepted with the Security Association, Proposal, and
Transform payloads. And responder send HASH(2) and Nonce.
HASH(2) is identical to HASH(1) except the initiator's nonce-- Ni,
minus the payload header-- is added after M-ID but before the
complete message. Nonce is random
information which is used to guarantee liveness.
3. Send the third message from TN
In the third (3) message, the initiator send HASH(3).
HASH(3)-- for liveliness-- is the prf over the
value zero represented as a single octet, followed by a concatenation
of the message id and the two nonces-- the initiator's followed by
the responder's-- minus the payload header.
The test sequence is following.
* IPsec transmission
# Initiator(TN) Direction Responder(NUT)
(1) IP_HDR; ESP*;
ICMP(Echo request) ========> <------Sequence Number:1
(2) IP_HDR; ESP*;
<======== ICMP(Echo reply)
(3) IP_HDR; ESP*;
ICMP(Echo request) ========> <------Sequence Number:1(invalid)
(4) IP_HDR; ESP*;
X <======== ICMP(Echo reply) <------Must not transmit
Judgement (Check *1)
1. Send the first message from TN
In the first message (1), initiator(TN) send Echo request
(Sequence Number:1)to responder(NUT) with IPsec SA.
2. Receive the second message from NUT
In the second message (2), responder(NUT) send Echo reply to initiator
(TN) with IPsec SA.
3. Send the third message from TN
In the third message (3), initiator(TN) send Echo request
(Sequence Number:1(invalid)) to responder(NUT) with IPsec SA.
4. Receive the second message from NUT
In the fourth message (4), responder(NUT) send Echo reply to initiator
(TN) with IPsec SA.
In Phase I , messages must be exchanged correctly.
In Phase II , the first to the third message must be exchanged correctly,
In IPsec SA transmission, the third message must not be accepted.
And fourth message must not be returned.
Clean up SAD and SPD
RFC2406
3.4.3 Sequence Number Verification
All ESP implementations MUST support the anti-replay service, though
its use may be enabled or disabled by the receiver on a per-SA basis.
This service MUST NOT be enabled unless the authentication service
also is enabled for the SA, since otherwise the Sequence Number field
has not been integrity protected. (Note that there are no provisions
for managing transmitted Sequence Number values among multiple
senders directing traffic to a single SA (irrespective of whether the
destination address is unicast, broadcast, or multicast). Thus the
anti-replay service SHOULD NOT be used in a multi-sender environment
that employs a single SA.)
If the receiver does not enable anti-replay for an SA, no inbound
checks are performed on the Sequence Number. However, from the
perspective of the sender, the default is to assume that anti-replay
is enabled at the receiver. To avoid having the sender do
unnecessary sequence number monitoring and SA setup (see section
3.3.3), if an SA establishment protocol such as IKE is employed, the
receiver SHOULD notify the sender, during SA establishment, if the
receiver will not provide anti-replay protection.
If the receiver has enabled the anti-replay service for this SA, the
receive packet counter for the SA MUST be initialized to zero when
the SA is established. For each received packet, the receiver MUST
verify that the packet contains a Sequence Number that does not
duplicate the Sequence Number of any other packets received during
the life of this SA. This SHOULD be the first ESP check applied to a
packet after it has been matched to an SA, to speed rejection of
duplicate packets.
Duplicates are rejected through the use of a sliding receive window.
(How the window is implemented is a local matter, but the following
text describes the functionality that the implementation must
exhibit.) A MINIMUM window size of 32 MUST be supported; but a
window size of 64 is preferred and SHOULD be employed as the default.
Another window size (larger than the MINIMUM) MAY be chosen by the
receiver. (The receiver does NOT notify the sender of the window
size.)
The "right" edge of the window represents the highest, validated
Sequence Number value received on this SA. Packets that contain
Sequence Numbers lower than the "left" edge of the window are
rejected. Packets falling within the window are checked against a
list of received packets within the window. An efficient means for
performing this check, based on the use of a bit mask, is described
in the Security Architecture document.
If the received packet falls within the window and is new, or if the
packet is to the right of the window, then the receiver proceeds to
ICV verification. If the ICV validation fails, the receiver MUST
discard the received IP datagram as invalid; this is an auditable
event. The audit log entry for this event SHOULD include the SPI
value, date/time received, Source Address, Destination Address, the
Sequence Number, and (in IPv6) the Flow ID. The receive window is
updated only if the ICV verification succeeds.
DISCUSSION:
Note that if the packet is either inside the window and new, or is
outside the window on the "right" side, the receiver MUST
authenticate the packet before updating the Sequence Number window
data.
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