QUIC-LB: Generating Routable QUIC Connection IDs
draft-ietf-quic-load-balancers-09
The information below is for an old version of the document.
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| Authors | Martin Duke , Nick Banks | ||
| Last updated | 2021-10-25 (Latest revision 2021-10-04) | ||
| Replaces | draft-duke-quic-load-balancers | ||
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draft-ietf-quic-load-balancers-09
QUIC M. Duke
Internet-Draft F5 Networks, Inc.
Intended status: Standards Track N. Banks
Expires: 28 April 2022 Microsoft
25 October 2021
QUIC-LB: Generating Routable QUIC Connection IDs
draft-ietf-quic-load-balancers-09
Abstract
The QUIC protocol design is resistant to transparent packet
inspection, injection, and modification by intermediaries. However,
the server can explicitly cooperate with network services by agreeing
to certain conventions and/or sharing state with those services.
This specification provides a standardized means of solving three
problems: (1) maintaining routability to servers via a low-state load
balancer even when the connection IDs in use change; (2) explicit
encoding of the connection ID length in all packets to assist
hardware accelerators; and (3) injection of QUIC Retry packets by an
anti-Denial-of-Service agent on behalf of the server.
Note to Readers
Discussion of this document takes place on the QUIC Working Group
mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/quic/
(https://mailarchive.ietf.org/arch/browse/quic/).
Source for this draft and an issue tracker can be found at
https://github.com/quicwg/load-balancers (https://github.com/quicwg/
load-balancers).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 28 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Notation . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Protocol Objectives . . . . . . . . . . . . . . . . . . . . . 6
2.1. Simplicity . . . . . . . . . . . . . . . . . . . . . . . 6
2.2. Security . . . . . . . . . . . . . . . . . . . . . . . . 6
3. First CID octet . . . . . . . . . . . . . . . . . . . . . . . 7
3.1. Config Rotation . . . . . . . . . . . . . . . . . . . . . 7
3.2. Configuration Failover . . . . . . . . . . . . . . . . . 8
3.3. Length Self-Description . . . . . . . . . . . . . . . . . 8
3.4. Format . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Load Balancing Preliminaries . . . . . . . . . . . . . . . . 9
4.1. Unroutable Connection IDs . . . . . . . . . . . . . . . . 9
4.2. Fallback Algorithms . . . . . . . . . . . . . . . . . . . 10
4.3. Server ID Allocation . . . . . . . . . . . . . . . . . . 11
4.4. CID format . . . . . . . . . . . . . . . . . . . . . . . 11
5. Routing Algorithms . . . . . . . . . . . . . . . . . . . . . 12
5.1. Plaintext CID Algorithm . . . . . . . . . . . . . . . . . 12
5.1.1. Configuration Agent Actions . . . . . . . . . . . . . 12
5.1.2. Load Balancer Actions . . . . . . . . . . . . . . . . 12
5.1.3. Server Actions . . . . . . . . . . . . . . . . . . . 13
5.2. Stream Cipher CID Algorithm . . . . . . . . . . . . . . . 13
5.2.1. Configuration Agent Actions . . . . . . . . . . . . . 13
5.2.2. Load Balancer Actions . . . . . . . . . . . . . . . . 13
5.2.3. Server Actions . . . . . . . . . . . . . . . . . . . 14
5.3. Block Cipher CID Algorithm . . . . . . . . . . . . . . . 14
5.3.1. Configuration Agent Actions . . . . . . . . . . . . . 15
5.3.2. Load Balancer Actions . . . . . . . . . . . . . . . . 15
5.3.3. Server Actions . . . . . . . . . . . . . . . . . . . 15
6. ICMP Processing . . . . . . . . . . . . . . . . . . . . . . . 15
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7. Retry Service . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Common Requirements . . . . . . . . . . . . . . . . . . . 16
7.1.1. Considerations for Non-Initial Packets . . . . . . . 17
7.2. No-Shared-State Retry Service . . . . . . . . . . . . . . 18
7.2.1. Configuration Agent Actions . . . . . . . . . . . . . 18
7.2.2. Service Requirements . . . . . . . . . . . . . . . . 18
7.2.3. Server Requirements . . . . . . . . . . . . . . . . . 20
7.3. Shared-State Retry Service . . . . . . . . . . . . . . . 21
7.3.1. Token Protection with AEAD . . . . . . . . . . . . . 23
7.3.2. Configuration Agent Actions . . . . . . . . . . . . . 24
7.3.3. Service Requirements . . . . . . . . . . . . . . . . 24
7.3.4. Server Requirements . . . . . . . . . . . . . . . . . 25
8. Configuration Requirements . . . . . . . . . . . . . . . . . 25
9. Additional Use Cases . . . . . . . . . . . . . . . . . . . . 26
9.1. Load balancer chains . . . . . . . . . . . . . . . . . . 26
9.2. Moving connections between servers . . . . . . . . . . . 26
10. Version Invariance of QUIC-LB . . . . . . . . . . . . . . . . 27
11. Security Considerations . . . . . . . . . . . . . . . . . . . 28
11.1. Attackers not between the load balancer and server . . . 28
11.2. Attackers between the load balancer and server . . . . . 29
11.3. Multiple Configuration IDs . . . . . . . . . . . . . . . 29
11.4. Limited configuration scope . . . . . . . . . . . . . . 29
11.5. Stateless Reset Oracle . . . . . . . . . . . . . . . . . 30
11.6. Connection ID Entropy . . . . . . . . . . . . . . . . . 30
11.7. Shared-State Retry Keys . . . . . . . . . . . . . . . . 31
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
13.1. Normative References . . . . . . . . . . . . . . . . . . 32
13.2. Informative References . . . . . . . . . . . . . . . . . 33
Appendix A. QUIC-LB YANG Model . . . . . . . . . . . . . . . . . 34
A.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 39
Appendix B. Load Balancer Test Vectors . . . . . . . . . . . . . 40
B.1. Plaintext Connection ID Algorithm . . . . . . . . . . . . 40
B.2. Stream Cipher Connection ID Algorithm . . . . . . . . . . 41
B.3. Block Cipher Connection ID Algorithm . . . . . . . . . . 41
B.4. Shared State Retry Tokens . . . . . . . . . . . . . . . . 41
Appendix C. Interoperability with DTLS over UDP . . . . . . . . 42
C.1. DTLS 1.0 and 1.2 . . . . . . . . . . . . . . . . . . . . 42
C.2. DTLS 1.3 . . . . . . . . . . . . . . . . . . . . . . . . 43
C.3. Future Versions of DTLS . . . . . . . . . . . . . . . . . 43
Appendix D. Acknowledgments . . . . . . . . . . . . . . . . . . 43
Appendix E. Change Log . . . . . . . . . . . . . . . . . . . . . 44
E.1. since draft-ietf-quic-load-balancers-08 . . . . . . . . . 44
E.2. since draft-ietf-quic-load-balancers-07 . . . . . . . . . 44
E.3. since draft-ietf-quic-load-balancers-06 . . . . . . . . . 44
E.4. since draft-ietf-quic-load-balancers-05 . . . . . . . . . 44
E.5. since draft-ietf-quic-load-balancers-04 . . . . . . . . . 44
E.6. since-draft-ietf-quic-load-balancers-03 . . . . . . . . . 45
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E.7. since-draft-ietf-quic-load-balancers-02 . . . . . . . . . 45
E.8. since-draft-ietf-quic-load-balancers-01 . . . . . . . . . 45
E.9. since-draft-ietf-quic-load-balancers-00 . . . . . . . . . 46
E.10. Since draft-duke-quic-load-balancers-06 . . . . . . . . . 46
E.11. Since draft-duke-quic-load-balancers-05 . . . . . . . . . 46
E.12. Since draft-duke-quic-load-balancers-04 . . . . . . . . . 46
E.13. Since draft-duke-quic-load-balancers-03 . . . . . . . . . 46
E.14. Since draft-duke-quic-load-balancers-02 . . . . . . . . . 46
E.15. Since draft-duke-quic-load-balancers-01 . . . . . . . . . 47
E.16. Since draft-duke-quic-load-balancers-00 . . . . . . . . . 47
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 47
1. Introduction
QUIC packets [RFC9000] usually contain a connection ID to allow
endpoints to associate packets with different address/port 4-tuples
to the same connection context. This feature makes connections
robust in the event of NAT rebinding. QUIC endpoints usually
designate the connection ID which peers use to address packets.
Server-generated connection IDs create a potential need for out-of-
band communication to support QUIC.
QUIC allows servers (or load balancers) to designate an initial
connection ID to encode useful routing information for load
balancers. It also encourages servers, in packets protected by
cryptography, to provide additional connection IDs to the client.
This allows clients that know they are going to change IP address or
port to use a separate connection ID on the new path, thus reducing
linkability as clients move through the world.
There is a tension between the requirements to provide routing
information and mitigate linkability. Ultimately, because new
connection IDs are in protected packets, they must be generated at
the server if the load balancer does not have access to the
connection keys. However, it is the load balancer that has the
context necessary to generate a connection ID that encodes useful
routing information. In the absence of any shared state between load
balancer and server, the load balancer must maintain a relatively
expensive table of server-generated connection IDs, and will not
route packets correctly if they use a connection ID that was
originally communicated in a protected NEW_CONNECTION_ID frame.
This specification provides common algorithms for encoding the server
mapping in a connection ID given some shared parameters. The mapping
is generally only discoverable by observers that have the parameters,
preserving unlinkability as much as possible.
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Aside from load balancing, a QUIC server may also desire to offload
other protocol functions to trusted intermediaries. These
intermediaries might include hardware assist on the server host
itself, without access to fully decrypted QUIC packets. For example,
this document specifies a means of offloading stateless retry to
counter Denial of Service attacks. It also proposes a system for
self-encoding connection ID length in all packets, so that crypto
offload can consistently look up key information.
While this document describes a small set of configuration parameters
to make the server mapping intelligible, the means of distributing
these parameters between load balancers, servers, and other trusted
intermediaries is out of its scope. There are numerous well-known
infrastructures for distribution of configuration.
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying significance described in RFC 2119.
In this document, "client" and "server" refer to the endpoints of a
QUIC connection unless otherwise indicated. A "load balancer" is an
intermediary for that connection that does not possess QUIC
connection keys, but it may rewrite IP addresses or conduct other IP
or UDP processing. A "configuration agent" is the entity that
determines the QUIC-LB configuration parameters for the network and
leverages some system to distribute that configuration.
Note that stateful load balancers that act as proxies, by terminating
a QUIC connection with the client and then retrieving data from the
server using QUIC or another protocol, are treated as a server with
respect to this specification.
For brevity, "Connection ID" will often be abbreviated as "CID".
1.2. Notation
All wire formats will be depicted using the notation defined in
Section 1.3 of [RFC9000]. There is one addition: the function len()
refers to the length of a field which can serve as a limit on a
different field, so that the lengths of two fields can be concisely
defined as limited to a sum, for example:
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x(A..B) y(C..B-len(x))
indicates that x can be of any length between A and B, and y can be
of any length between C and B provided that (len(x) + len(y)) does
not exceed B.
The example below illustrates the basic framework:
Example Structure {
One-bit Field (1),
7-bit Field with Fixed Value (7) = 61,
Field with Variable-Length Integer (i),
Arbitrary-Length Field (..),
Variable-Length Field (8..24),
Variable-Length Field with Dynamic Limit (8..24-len(Variable-Length Field)),
Field With Minimum Length (16..),
Field With Maximum Length (..128),
[Optional Field (64)],
Repeated Field (8) ...,
}
Figure 1: Example Format
2. Protocol Objectives
2.1. Simplicity
QUIC is intended to provide unlinkability across connection
migration, but servers are not required to provide additional
connection IDs that effectively prevent linkability. If the
coordination scheme is too difficult to implement, servers behind
load balancers using connection IDs for routing will use trivially
linkable connection IDs. Clients will therefore be forced to choose
between terminating the connection during migration or remaining
linkable, subverting a design objective of QUIC.
The solution should be both simple to implement and require little
additional infrastructure for cryptographic keys, etc.
2.2. Security
In the limit where there are very few connections to a pool of
servers, no scheme can prevent the linking of two connection IDs with
high probability. In the opposite limit, where all servers have many
connections that start and end frequently, it will be difficult to
associate two connection IDs even if they are known to map to the
same server.
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QUIC-LB is relevant in the region between these extremes: when the
information that two connection IDs map to the same server is helpful
to linking two connection IDs. Obviously, any scheme that
transparently communicates this mapping to outside observers
compromises QUIC's defenses against linkability.
Though not an explicit goal of the QUIC-LB design, concealing the
server mapping also complicates attempts to focus attacks on a
specific server in the pool.
3. First CID octet
The first octet of a Connection ID is reserved for two special
purposes, one mandatory (config rotation) and one optional (length
self-description).
Subsequent sections of this document refer to the contents of this
octet as the "first octet."
3.1. Config Rotation
The first two bits of any connection ID MUST encode an identifier for
the configuration that the connection ID uses. This enables
incremental deployment of new QUIC-LB settings (e.g., keys).
When new configuration is distributed to servers, there will be a
transition period when connection IDs reflecting old and new
configuration coexist in the network. The rotation bits allow load
balancers to apply the correct routing algorithm and parameters to
incoming packets.
Configuration Agents SHOULD deliver new configurations to load
balancers before doing so to servers, so that load balancers are
ready to process CIDs using the new parameters when they arrive.
A Configuration Agent SHOULD NOT use a codepoint to represent a new
configuration until it takes precautions to make sure that all
connections using CIDs with an old configuration at that codepoint
have closed or transitioned.
Servers MUST NOT generate new connection IDs using an old
configuration after receiving a new one from the configuration agent.
Servers MUST send NEW_CONNECTION_ID frames that provide CIDs using
the new configuration, and retire CIDs using the old configuration
using the "Retire Prior To" field of that frame.
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It also possible to use these bits for more long-lived distinction of
different configurations, but this has privacy implications (see
Section 11.3).
3.2. Configuration Failover
If a server has not received a valid QUIC-LB configuration, and
believes that low-state, Connection-ID aware load balancers are in
the path, it SHOULD generate connection IDs with the config rotation
bits set to '11' and SHOULD use the "disable_active_migration"
transport parameter in all new QUIC connections. It SHOULD NOT send
NEW_CONNECTION_ID frames with new values.
A load balancer that sees a connection ID with config rotation bits
set to '11' MUST revert to 5-tuple routing. These connection IDs may
be of any length; however, see Section 11.6 for limits on this
length.
3.3. Length Self-Description
Local hardware cryptographic offload devices may accelerate QUIC
servers by receiving keys from the QUIC implementation indexed to the
connection ID. However, on physical devices operating multiple QUIC
servers, it is impractical to efficiently lookup these keys if the
connection ID does not self-encode its own length.
Note that this is a function of particular server devices and is
irrelevant to load balancers. As such, load balancers MAY omit this
from their configuration. However, the remaining 6 bits in the first
octet of the Connection ID are reserved to express the length of the
following connection ID, not including the first octet.
A server not using this functionality SHOULD make the six bits appear
to be random.
3.4. Format
First Octet {
Config Rotation (2),
CID Len or Random Bits (6),
}
Figure 2: First Octet Format
The first octet has the following fields:
Config Rotation: Indicates the configuration used to interpret the
CID.
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CID Len or Random Bits: Length Self-Description (if applicable), or
random bits otherwise. Encodes the length of the Connection ID
following the First Octet.
4. Load Balancing Preliminaries
In QUIC-LB, load balancers do not generate individual connection IDs
for servers. Instead, they communicate the parameters of an
algorithm to generate routable connection IDs.
The algorithms differ in the complexity of configuration at both load
balancer and server. Increasing complexity improves obfuscation of
the server mapping.
This section describes three participants: the configuration agent,
the load balancer, and the server. For any given QUIC-LB
configuration that enables connection-ID-aware load balancing, there
must be a choice of (1) routing algorithm, (2) server ID allocation
strategy, and (3) algorithm parameters.
Fundamentally, servers generate connection IDs that encode their
server ID. Load balancers decode the server ID from the CID in
incoming packets to route to the correct server.
There are situations where a server pool might be operating two or
more routing algorithms or parameter sets simultaneously. The load
balancer uses the first two bits of the connection ID to multiplex
incoming DCIDs over these schemes (see Section 3.1).
4.1. Unroutable Connection IDs
QUIC-LB servers will generate Connection IDs that are decodable to
extract a server ID in accordance with a specified algorithm and
parameters. However, QUIC often uses client-generated Connection IDs
prior to receiving a packet from the server.
These client-generated CIDs might not conform to the expectations of
the routing algorithm and therefore not be routable by the load
balancer. Those that are not routable are "unroutable DCIDs" and
receive similar treatment regardless of why they're unroutable:
* The config rotation bits (Section 3.1) may not correspond to an
active configuration. Note: a packet with a DCID that indicates
5-tuple routing (see Section 3.2) is always routable.
* The DCID might not be long enough for the decoder to process.
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* The extracted server mapping might not correspond to an active
server.
All other DCIDs are routable.
Load balancers MUST forward packets with routable DCIDs to a server
in accordance with the chosen routing algorithm.
Load balancers SHOULD drop short header packets with unroutable
DCIDs.
When forwarding a packet with a long header and unroutable DCID, load
balancers MUST use a fallback algorithm as specified in Section 4.2.
Load balancers MAY drop packets with long headers and unroutable
DCIDs if and only if it knows that the encoded QUIC version does not
allow an unroutable DCID in a packet with that signature. For
example, a load balancer can safely drop a QUIC version 1 Handshake
packet with an unroutable DCID, as a version 1 Handshake packet sent
to a QUIC-LB routable server will always have a server-generated
routable CID. The prohibition against dropping packets with long
headers remains for unknown QUIC versions.
Furthermore, while the load balancer function MUST NOT drop packets,
the device might implement other security policies, outside the scope
of this specification, that might force a drop.
Servers that receive packets with unroutable CIDs MUST use the
available mechanisms to induce the client to use a routable CID in
future packets. In QUIC version 1, this requires using a routable
CID in the Source CID field of server-generated long headers.
4.2. Fallback Algorithms
There are conditions described below where a load balancer routes a
packet using a "fallback algorithm." It can choose any algorithm,
without coordination with the servers, but the algorithm SHOULD be
deterministic over short time scales so that related packets go to
the same server. The design of this algorithm SHOULD consider the
version-invariant properties of QUIC described in [RFC8999] to
maximize its robustness to future versions of QUIC.
A fallback algorithm MUST NOT make the routing behavior dependent on
any bits in the first octet of the QUIC packet header, except the
first bit, which indicates a long header. All other bits are QUIC
version-dependent and intermediaries SHOULD NOT base their design on
version-specific templates.
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For example, one fallback algorithm might convert a unroutable DCID
to an integer and divided by the number of servers, with the modulus
used to forward the packet. The number of servers is usually
consistent on the time scale of a QUIC connection handshake. Another
might simply hash the address/port 4-tuple. See also Section 10.
4.3. Server ID Allocation
Load Balancer configurations include a mapping of server IDs to
forwarding addresses. The corresponding server configurations
contain one or more unique server IDs.
The configuration agent chooses a server ID length for each
configuration that MUST be at least one octet.
A QUIC-LB configuration MAY significantly over-provision the server
ID space (i.e., provide far more codepoints than there are servers)
to increase the probability that a randomly generated Destination
Connection ID is unroutable.
The configuration agent SHOULD provide a means for servers to express
the number of server IDs it can usefully employ, because a single
routing address actually corresponds to multiple server entities (see
Section 9.1).
Conceptually, each configuration has its own set of server ID
allocations, though two static configurations with identical server
ID lengths MAY use a common allocation between them.
A server encodes one of its assigned server IDs in any CID it
generates using the relevant configuration.
4.4. CID format
All connection IDs use the following format:
QUIC-LB Connection ID {
First Octet (8),
Server ID (8..152-len(Nonce)),
Nonce (32..152-len(Server ID),
}
Figure 3: CID Format
Each configuration specifies the length of the Server ID and Nonce
fields, with limits defined for each algorithm. When using a given
configuration, the server MUST generate CIDs of length equal to the
lengths of these three fields.
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The Server ID is assigned to each server in accordance with
Section 4.3. Dynamically allocated SIDs are limited to seven octets
or fewer. Statically allocated ones have different limits for each
algorithm.
The configuration agent assigns a server ID to every server in its
pool, and determines a server ID length (in octets) sufficiently
large to encode all server IDs, including potential future servers.
The Nonce is selected by the server when it generates a CID. As the
name implies, a server MUST use a nonce no more than once when
generating a CID for a given server ID and unique set of
configuration parameters.
The nonce length MUST be at least 4 octets. Additional limits on its
length are different for each algorithm. See Section 11.6 for limits
on nonce generation.
As QUIC version 1 limits connection IDs to 20 octets, the server ID
and nonce lengths MUST sum to 19 octets or less.
5. Routing Algorithms
Encryption in the algorithms below uses the AES-128-ECB cipher.
Future standards could add new algorithms that use other ciphers to
provide cryptographic agility in accordance with [RFC7696]. QUIC-LB
implementations SHOULD be extensible to support new algorithms.
5.1. Plaintext CID Algorithm
The Plaintext CID Algorithm makes no attempt to obscure the mapping
of connections to servers, significantly increasing linkability.
5.1.1. Configuration Agent Actions
See Section 4.4.
5.1.2. Load Balancer Actions
On each incoming packet, the load balancer extracts consecutive
octets, beginning with the second octet. These bytes represent the
server ID. It ignores the nonce.
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5.1.3. Server Actions
When a server needs a new connection ID, it encodes one of its
assigned server IDs in consecutive octets beginning with the second
and chooses a nonce. This nonce MUST appear to be random (see
Section 11.6).
5.2. Stream Cipher CID Algorithm
The Stream Cipher CID algorithm provides cryptographic protection at
the cost of additional per-packet processing at the load balancer to
decrypt every incoming connection ID.
5.2.1. Configuration Agent Actions
The nonce length MUST be no fewer than 4 octets.
The configuration agent also selects an 16-octet AES-ECB key to use
for connection ID decryption.
5.2.2. Load Balancer Actions
Upon receipt of a QUIC packet, the load balancer extracts as many of
the earliest octets from the destination connection ID as necessary
to match the server ID. The nonce immediately follows.
The load balancer decrypts the nonce and the server ID using the
following three pass algorithm:
* Pass 1: The load balancer decrypts the server ID using 128-bit AES
Electronic Codebook (ECB) mode, much like QUIC header protection.
The encrypted nonce octets are zero-padded to 16 octets. AES-ECB
encrypts this encrypted nonce using its key to generate a mask
which it applies to the encrypted server id. This provides an
intermediate value of the server ID, referred to as server-id
intermediate.
server_id_intermediate = encrypted_server_id ^ AES-ECB(key, padded-
encrypted-nonce)
* Pass 2: The load balancer decrypts the nonce octets using 128-bit
AES ECB mode, using the server-id intermediate as "nonce" for this
pass. The server-id intermediate octets are zero-padded to 16
octets. AES-ECB encrypts this padded server-id intermediate using
its key to generate a mask which it applies to the encrypted
nonce. This provides the decrypted nonce value.
nonce = encrypted_nonce ^ AES-ECB(key, padded-server_id_intermediate)
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* Pass 3: The load balancer decrypts the server ID using 128-bit AES
ECB mode. The nonce octets are zero-padded to 16 octets. AES-ECB
encrypts this nonce using its key to generate a mask which it
applies to the intermediate server id. This provides the
decrypted server ID.
server_id = server_id_intermediate ^ AES-ECB(key, padded-nonce)
For example, if the nonce length is 10 octets and the server ID
length is 2 octets, the connection ID can be as small as 13 octets.
The load balancer uses the the second through eleventh octets of the
connection ID for the nonce, zero-pads it to 16 octets, uses xors the
result with the twelfth and thirteenth octet. The result is padded
with 14 octets of zeros and encrypted to obtain a mask that is xored
with the nonce octets. Finally, the nonce octets are padded with six
octets of zeros, encrypted, and the first two octets xored with the
server ID octets to obtain the actual server ID.
This three-pass algorithm is a simplified version of the FFX
algorithm, with the property that each encrypted nonce value depends
on all server ID bits, and each encrypted server ID bit depends on
all nonce bits and all server ID bits. This mitigates attacks
against stream ciphers in which attackers simply flip encrypted
server-ID bits.
The output of the decryption is the server ID that the load balancer
uses for routing.
5.2.3. Server Actions
When generating a routable connection ID, the server writes arbitrary
bits into its nonce octets, and its provided server ID into the
server ID octets. See Section 11.6 for nonce generation
considerations.
The server encrypts the server ID using exactly the algorithm as
described in Section 5.2.2, performing the three passes in reverse
order.
5.3. Block Cipher CID Algorithm
The Block Cipher CID Algorithm, by using a full 16 octets of
plaintext and a 128-bit cipher, provides higher cryptographic
protection and detection of unroutable connection IDs. However, it
also requires connection IDs of at least 17 octets, increasing
overhead of client-to-server packets.
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5.3.1. Configuration Agent Actions
The server ID length MUST be no more than 12 octets. The nonce and
server ID MUST sum to at least 16 octets.
The configuration agent also selects an 16-octet AES-ECB key to use
for connection ID decryption.
5.3.2. Load Balancer Actions
Upon receipt of a QUIC packet, the load balancer reads the first
octet to obtain the config rotation bits. It then decrypts the
subsequent 16 octets using AES-ECB decryption and the chosen key.
The first octets of the plaintext contains the server id.
5.3.3. Server Actions
The server encrypts both its server ID and enough octets in a nonce
to form a 16-octet block using the configured AES-ECB key. Note that
any remaining octets in the nonce are transmitted as plaintext, and
should consider the constraints in Section 11.6.
6. ICMP Processing
For protocols where 4-tuple load balancing is sufficient, it is
straightforward to deliver ICMP packets from the network to the
correct server, by reading the echoed IP and transport-layer headers
to obtain the 4-tuple. When routing is based on connection ID,
further measures are required, as most QUIC packets that trigger ICMP
responses will only contain a client-generated connection ID that
contains no routing information.
To solve this problem, load balancers MAY maintain a mapping of
Client IP and port to server ID based on recently observed packets.
Alternatively, servers MAY implement the technique described in
Section 14.4.1 of [RFC9000] to increase the likelihood a Source
Connection ID is included in ICMP responses to Path Maximum
Transmission Unit (PMTU) probes. Load balancers MAY parse the echoed
packet to extract the Source Connection ID, if it contains a QUIC
long header, and extract the Server ID as if it were in a Destination
CID.
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7. Retry Service
When a server is under load, QUICv1 allows it to defer storage of
connection state until the client proves it can receive packets at
its advertised IP address. Through the use of a Retry packet, a
token in subsequent client Initial packets, and transport parameters,
servers verify address ownership and clients verify that there is no
on-path attacker generating Retry packets.
A "Retry Service" detects potential Denial of Service attacks and
handles sending of Retry packets on behalf of the server. As it is,
by definition, literally an on-path entity, the service must
communicate some of the original connection IDs back to the server so
that it can pass client verification. It also must either verify the
address itself (with the server trusting this verification) or make
sure there is common context for the server to verify the address
using a service-generated token.
There are two different mechanisms to allow offload of DoS mitigation
to a trusted network service. One requires no shared state; the
server need only be configured to trust a retry service, though this
imposes other operational constraints. The other requires a shared
key, but has no such constraints.
7.1. Common Requirements
Regardless of mechanism, a retry service has an active mode, where it
is generating Retry packets, and an inactive mode, where it is not,
based on its assessment of server load and the likelihood an attack
is underway. The choice of mode MAY be made on a per-packet or per-
connection basis, through a stochastic process or based on client
address.
A configuration agent MUST distribute a list of QUIC versions the
Retry Service supports. It MAY also distribute either an "Allow-
List" or a "Deny-List" of other QUIC versions. It MUST NOT
distribute both an Allow-List and a Deny-List.
The Allow-List or Deny-List MUST NOT include any versions included
for Retry Service Support.
The Configuration Agent MUST provide a means for the entity that
controls the Retry Service to report its supported version(s) to the
configuration Agent. If the entity has not reported this
information, it MUST NOT activate the Retry Service and the
configuration agent MUST NOT distribute configuration that activates
it.
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The configuration agent MAY delete versions from the final supported
version list if policy does not require the Retry Service to operate
on those versions.
The configuration Agent MUST provide a means for the entities that
control servers behind the Retry Service to report either an Allow-
List or a Deny-List.
If all entities supply Allow-Lists, the consolidated list MUST be the
union of these sets. If all entities supply Deny-Lists, the
consolidated list MUST be the intersection of these sets.
If entities provide a mixture of Allow-Lists and Deny-Lists, the
consolidated list MUST be a Deny-List that is the intersection of all
provided Deny-Lists and the inverses of all Allow-Lists.
If no entities that control servers have reported Allow-Lists or
Deny-Lists, the default is a Deny-List with the null set (i.e., all
unsupported versions will be admitted). This preserves the future
extensibilty of QUIC.
A retry service MUST forward all packets for a QUIC version it does
not support that are not on a Deny-List or absent from an Allow-List.
Note that if servers support versions the retry service does not,
this may increase load on the servers.
Note that future versions of QUIC might not have Retry packets,
require different information in Retry, or use different packet type
indicators.
7.1.1. Considerations for Non-Initial Packets
Initial Packets are especially effective at consuming server
resources because they cause the server to create connection state.
Even when mitigating this load with Retry Packets, the act of
validating an Initial Token and sending a Retry Packet is more
expensive than the response to a non-Initial packet with an unknown
Connection ID: simply dropping it and/or sending a Stateless Reset.
Nevertheless, a Retry Service in Active Mode might desire to shield
servers from non-Initial packets that do not correspond to a
previously admitted Initial Packet. This has a number of
considerations.
* If a Retry Service maintains no per-flow state whatsoever, it
cannot distinguish between valid and invalid non-Initial packets
and MUST forward all non-Initial Packets to the server.
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* For QUIC versions the Retry Service does not support and are
present on the Allow-List (or absent from the Deny-List), the
Retry Service cannot distinguish Initial Packets from other long
headers and therefore MUST admit all long headers.
* If a Retry Service keeps per-flow state, it can identify 4-tuples
that have been previously approved, admit non-Initial packets from
those flows, and drop all others. However, dropping short headers
will effectively break Address Migration and NAT Rebinding when in
Active Mode, as post-migration packets will arrive with a
previously unknown 4-tuple. This policy will also break
connection attempts using any new QUIC versions that begin
connections with a short header.
* If a Retry Service is integrated with a QUIC-LB routable load
balancer, it can verify that the Destination Connection ID is
routable, and only admit non-Initial packets with routable DCIDs.
As the Connection ID encoding is invariant across QUIC versions,
the Retry Service can do this for all short headers.
Nothing in this section prevents Retry Services from making basic
syntax correctness checks on packets with QUIC versions that it
understands (e.g., enforcing the Initial Packet datagram size minimum
in version 1) and dropping packets that are not routable with the
QUIC specification.
7.2. No-Shared-State Retry Service
The no-shared-state retry service requires no coordination, except
that the server must be configured to accept this service and know
which QUIC versions the retry service supports. The scheme uses the
first bit of the token to distinguish between tokens from Retry
packets (codepoint '0') and tokens from NEW_TOKEN frames (codepoint
'1').
7.2.1. Configuration Agent Actions
See Section 7.1.
7.2.2. Service Requirements
A no-shared-state retry service MUST be present on all paths from
potential clients to the server. These paths MUST fail to pass QUIC
traffic should the service fail for any reason. That is, if the
service is not operational, the server MUST NOT be exposed to client
traffic. Otherwise, servers that have already disabled their Retry
capability would be vulnerable to attack.
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The path between service and server MUST be free of any potential
attackers. Note that this and other requirements above severely
restrict the operational conditions in which a no-shared-state retry
service can safely operate.
Retry tokens generated by the service MUST have the format below.
Non-Shared-State Retry Service Token {
Token Type (1) = 0,
ODCIL (7) = 8..20,
Original Destination Connection ID (64..160),
Opaque Data (..),
}
Figure 4: Format of non-shared-state retry service tokens
The first bit of retry tokens generated by the service MUST be zero.
The token has the following additional fields:
ODCIL: The length of the original destination connection ID from the
triggering Initial packet. This is in cleartext to be readable for
the server, but authenticated later in the token. The Retry Service
SHOULD reject any token in which the value is less than 8.
Original Destination Connection ID: This also in cleartext and
authenticated later.
Opaque Data: This data contains the information necessary to
authenticate the Retry token in accordance with the QUIC
specification. A straightforward implementation would encode the
Retry Source Connection ID, client IP address, and a timestamp in the
Opaque Data. A more space-efficient implementation would use the
Retry Source Connection ID and Client IP as associated data in an
encryption operation, and encode only the timestamp and the
authentication tag in the Opaque Data. If the Initial Packet has
altered the Connection ID or source IP address, authentication of the
token will fail.
Upon receipt of an Initial packet with a token that begins with '0',
the retry service MUST validate the token in accordance with the QUIC
specification.
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In active mode, the service MUST issue Retry packets for all Client
initial packets that contain no token, or a token that has the first
bit set to '1'. It MUST NOT forward the packet to the server. The
service MUST validate all tokens with the first bit set to '0'. If
successful, the service MUST forward the packet with the token
intact. If unsuccessful, it MUST drop the packet. The Retry Service
MAY send an Initial Packet containing a CONNECTION_CLOSE frame with
the INVALID_TOKEN error code when dropping the packet.
Note that this scheme has a performance drawback. When the retry
service is in active mode, clients with a token from a NEW_TOKEN
frame will suffer a 1-RTT penalty even though its token provides
proof of address.
In inactive mode, the service MUST forward all packets that have no
token or a token with the first bit set to '1'. It MUST validate all
tokens with the first bit set to '0'. If successful, the service
MUST forward the packet with the token intact. If unsuccessful, it
MUST either drop the packet or forward it with the token removed.
The latter requires decryption and re-encryption of the entire
Initial packet to avoid authentication failure. Forwarding the
packet causes the server to respond without the
original_destination_connection_id transport parameter, which
preserves the normal QUIC signal to the client that there is an on-
path attacker.
7.2.3. Server Requirements
A server behind a non-shared-state retry service MUST NOT send Retry
packets for a QUIC version the retry service understands. It MAY
send Retry for QUIC versions the Retry Service does not understand.
Tokens sent in NEW_TOKEN frames MUST have the first bit set to '1'.
If a server receives an Initial Packet with the first bit set to '1',
it could be from a server-generated NEW_TOKEN frame and should be
processed in accordance with the QUIC specification. If a server
receives an Initial Packet with the first bit to '0', it is a Retry
token and the server MUST NOT attempt to validate it. Instead, it
MUST assume the address is validated, MUST include the packet's
Destination Connection ID in a Retry Source Connection ID transport
parameter, and MUST extract the Original Destination Connection ID
from the token cleartext for use in the transport parameter of the
same name.
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7.3. Shared-State Retry Service
A shared-state retry service uses a shared key, so that the server
can decode the service's retry tokens. It does not require that all
traffic pass through the Retry service, so servers MAY send Retry
packets in response to Initial packets that don't include a valid
token.
Both server and service must have time synchronized with respect to
one another to prevent tokens being incorrectly marked as expired,
though tight synchronization is unnecessary.
The tokens are protected using AES128-GCM AEAD, as explained in
Section 7.3.1. All tokens, generated by either the server or retry
service, MUST use the following format, which includes:
* A 1 bit token type identifier.
* A 7 bit token key identifier.
* A 96 bit unique token number transmitted in clear text, but
protected as part of the AEAD associated data.
* A token body, encoding the Original Destination Connection ID and
the Timestamp, optionally followed by server specific Opaque Data.
The token protection uses an 128 bit representation of the source IP
address from the triggering Initial packet. The client IP address is
16 octets. If an IPv4 address, the last 12 octets are zeroes. It
also uses the Source Connection ID of the Retry packet, which will
cause an authentication failure if it differs from the Destination
Connection ID of the packet bearing the token.
If there is a Network Address Translator (NAT) in the server
infrastructure that changes the client IP, the Retry Service MUST
either be positioned behind the NAT, or the NAT must have the token
key to rewrite the Retry token accordingly. Note also that a host
that obtains a token through a NAT and then attempts to connect over
a path that does not have an identically configured NAT will fail
address validation.
The 96 bit unique token number is set to a random value using a
cryptography-grade random number generator.
The token key identifier and the corresponding AEAD key and AEAD IV
are provisioned by the configuration agent.
The token body is encoded as follows:
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Shared-State Retry Service Token Body {
Timestamp (64),
[ODCIL (8) = 8..20],
[Original Destination Connection ID (64..160)],
[Port (16)],
Opaque Data (..),
}
Figure 5: Body of shared-state retry service tokens
The token body has the following fields:
Timestamp: The Timestamp is a 64-bit integer, in network order, that
expresses the expiration time of the token as a number of seconds in
POSIX time (see Sec. 4.16 of [TIME_T]).
ODCIL: The original destination connection ID length. Tokens in
NEW_TOKEN frames do not have this field.
Original Destination Connection ID: The server or Retry Service
copies this from the field in the client Initial packet. Tokens in
NEW_TOKEN frames do not have this field.
Port: The Source Port of the UDP datagram that triggered the Retry
packet. This field MUST be present if and only if the ODCIL is
greater than zero. This field is therefore always absent in tokens
in NEW_TOKEN frames.
Opaque Data: The server may use this field to encode additional
information, such as congestion window, RTT, or MTU. The Retry
Service MUST have zero-length opaque data.
Some implementations of QUIC encode in the token the Initial Packet
Number used by the client, in order to verify that the client sends
the retried Initial with a PN larger that the triggering Initial.
Such implementations will encode the Initial Packet Number as part of
the opaque data. As tokens may be generated by the Service, servers
MUST NOT reject tokens because they lack opaque data and therefore
the packet number.
Shared-state Retry Services use the AES-128-ECB cipher. Future
standards could add new algorithms that use other ciphers to provide
cryptographic agility in accordance with [RFC7696]. Retry Service
and server implementations SHOULD be extensible to support new
algorithms.
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7.3.1. Token Protection with AEAD
On the wire, the token is presented as:
Shared-State Retry Service Token {
Token Type (1),
Key Sequence (7),
Unique Token Number (96),
Encrypted Shared-State Retry Service Token Body (64..),
AEAD Integrity Check Value (128),
}
Figure 6: Wire image of shared-state retry service tokens
The tokens are protected using AES128-GCM as follows:
* The Key Sequence is the 7 bit identifier to retrieve the token key
and IV.
* The AEAD IV, is a 96 bit data which produced by implementer's
custom AEAD IV derivation function.
* The AEAD nonce, N, is formed by combining the AEAD IV with the 96
bit unique token number. The 96 bits of the unique token number
are left-padded with zeros to the size of the IV. The exclusive
OR of the padded unique token number and the AEAD IV forms the
AEAD nonce.
* The associated data is a formatted as a pseudo header by combining
the cleartext part of the token with the IP address of the client.
The format of the pseudoheader depends on whether the Token Type
bit is '1' (a NEW_TOKEN token) or '0' (a Retry token).
Shared-State Retry Service Token Pseudoheader {
IP Address (128),
Token Type (1),
Key Sequence (7),
Unique Token Number (96),
[RSCIL (8)],
[Retry Source Connection ID (0..20)],
}
Figure 7: Psuedoheader for shared-state retry service tokens
RSCIL: The Retry Source Connection ID Length in octets. This field
is only present when the Token Type is '0'.
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Retry Source Connection ID: To create a Retry Token, populate this
field with the Source Connection ID the Retry packet will use. To
validate a Retry token, populate it with the Destination Connection
ID of the Initial packet that carries the token. This field is only
present when the Token Type is '0'.
* The input plaintext for the AEAD is the token body. The output
ciphertext of the AEAD is transmitted in place of the token body.
* The AEAD Integrity Check Value(ICV), defined in Section 6 of
[RFC4106], is computed as part of the AEAD encryption process, and
is verified during decryption.
7.3.2. Configuration Agent Actions
The configuration agent generates and distributes a "token key", a
"token IV", a key sequence, and the information described in
Section 7.1.
7.3.3. Service Requirements
In inactive mode, the Retry service forwards all packets without
further inspection or processing. The rest of this section only
applies to a service in active mode.
Retry services MUST NOT issue Retry packets except where explicitly
allowed below, to avoid sending a Retry packet in response to a Retry
token.
The service MUST generate Retry tokens with the format described
above when it receives a client Initial packet with no token.
If there is a token of either type, the service MUST attempt to
decrypt it.
To decrypt a packet, the service checks the Token Type and constructs
a pseudoheader with the appropriate format for that type, using the
bearing packet's Destination Connection ID to populate the Retry
Source Connection ID field, if any.
A token is invalid if:
* it uses unknown key sequence,
* the AEAD ICV does not match the expected value (By construction,
it will only match if the client IP Address, and any Retry Source
Connection ID, also matches),
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* the ODCIL, if present, is invalid for a client-generated CID (less
than 8 or more than 20 in QUIC version 1),
* the Timestamp of a token points to time in the past (however, in
order to allow for clock skew, it SHOULD NOT consider tokens to be
expired if the Timestamp encodes a few seconds in the past), or
* the port number, if present, does not match the source port in the
encapsulating UDP header.
Packets with valid tokens MUST be forwarded to the server.
The service MUST drop packets with invalid tokens. If the token is
of type '1' (NEW_TOKEN), it MUST respond with a Retry packet. If of
type '0', it MUST NOT respond with a Retry packet.
7.3.4. Server Requirements
The server MAY issue Retry or NEW_TOKEN tokens in accordance with
[RFC9000]. When doing so, it MUST follow the format above.
The server MUST validate all tokens that arrive in Initial packets,
as they may have bypassed the Retry service. It determines validity
using the procedure in Section 7.3.3.
If a valid Retry token, the server populates the
original_destination_connection_id transport parameter using the
corresponding token field. It populates the
retry_source_connection_id transport parameter with the Destination
Connection ID of the packet bearing the token.
In all other respects, the server processes both valid and invalid
tokens in accordance with [RFC9000].
For QUIC versions the service does not support, the server MAY use
any token format.
8. Configuration Requirements
QUIC-LB requires common configuration to synchronize understanding of
encodings and guarantee explicit consent of the server.
The load balancer and server MUST agree on a routing algorithm and
the relevant parameters for that algorithm.
All algorithm configurations can have a server ID length, nonce
length, and key. However, for Plaintext CID, there is no key.
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The load balancer MUST receive the full table of mappings, and each
server must receive its assigned SID(s), from the configuration
agent.
Note that server IDs are opaque bytes, not integers, so there is no
notion of network order or host order.
A server configuration MUST specify if the first octet encodes the
CID length. Note that a load balancer does not need the CID length,
as the required bytes are present in the QUIC packet.
A full QUIC-LB server configuration MUST also specify the supported
QUIC versions of any Retry Service. If a shared-state service, the
server also must have the token key.
A non-shared-state Retry Service need only be configured with the
QUIC versions it supports, and an Allow- or Deny-List. A shared-
state Retry Service also needs the token key, and to be aware if a
NAT sits between it and the servers.
Appendix A provides a YANG Model of the a full QUIC-LB configuration.
9. Additional Use Cases
This section discusses considerations for some deployment scenarios
not implied by the specification above.
9.1. Load balancer chains
Some network architectures may have multiple tiers of low-state load
balancers, where a first tier of devices makes a routing decision to
the next tier, and so on, until packets reach the server. Although
QUIC-LB is not explicitly designed for this use case, it is possible
to support it.
If each load balancer is assigned a range of server IDs that is a
subset of the range of IDs assigned to devices that are closer to the
client, then the first devices to process an incoming packet can
extract the server ID and then map it to the correct forwarding
address. Note that this solution is extensible to arbitrarily large
numbers of load-balancing tiers, as the maximum server ID space is
quite large.
9.2. Moving connections between servers
Some deployments may transparently move a connection from one server
to another. The means of transferring connection state between
servers is out of scope of this document.
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To support a handover, a server involved in the transition could
issue CIDs that map to the new server via a NEW_CONNECTION_ID frame,
and retire CIDs associated with the new server using the "Retire
Prior To" field in that frame.
Alternately, if the old server is going offline, the load balancer
could simply map its server ID to the new server's address.
10. Version Invariance of QUIC-LB
Non-shared-state Retry Services are inherently dependent on the
format (and existence) of Retry Packets in each version of QUIC, and
so Retry Service configuration explicitly includes the supported QUIC
versions.
The server ID encodings, and requirements for their handling, are
designed to be QUIC version independent (see [RFC8999]). A QUIC-LB
load balancer will generally not require changes as servers deploy
new versions of QUIC. However, there are several unlikely future
design decisions that could impact the operation of QUIC-LB.
The maximum Connection ID length could be below the minimum necessary
for one or more encoding algorithms.
Section 4.1 provides guidance about how load balancers should handle
unroutable DCIDs. This guidance, and the implementation of an
algorithm to handle these DCIDs, rests on some assumptions:
* Incoming short headers do not contain DCIDs that are client-
generated.
* The use of client-generated incoming DCIDs does not persist beyond
a few round trips in the connection.
* While the client is using DCIDs it generated, some exposed fields
(IP address, UDP port, client-generated destination Connection ID)
remain constant for all packets sent on the same connection.
* Dynamic server ID allocation is dependent on client-generated
Destination CIDs in Initial Packets being at least 8 octets in
length. If they are not, the load balancer may not be able to
extract a valid server ID to add to its table. Configuring a
shorter server ID length can increase robustness to a change.
While this document does not update the commitments in [RFC8999], the
additional assumptions are minimal and narrowly scoped, and provide a
likely set of constants that load balancers can use with minimal risk
of version- dependence.
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If these assumptions are invalid, this specification is likely to
lead to loss of packets that contain unroutable DCIDs, and in extreme
cases connection failure.
Some load balancers might inspect elements of the Server Name
Indication (SNI) extension in the TLS Client Hello to make a routing
decision. Note that the format and cryptographic protection of this
information may change in future versions or extensions of TLS or
QUIC, and therefore this functionality is inherently not version-
invariant.
11. Security Considerations
QUIC-LB is intended to prevent linkability. Attacks would therefore
attempt to subvert this purpose.
Note that the Plaintext CID algorithm makes no attempt to obscure the
server mapping, and therefore does not address these concerns. It
exists to allow consistent CID encoding for compatibility across a
network infrastructure, which makes QUIC robust to NAT rebinding.
Servers that are running the Plaintext CID algorithm SHOULD only use
it to generate new CIDs for the Server Initial Packet and SHOULD NOT
send CIDs in QUIC NEW_CONNECTION_ID frames, except that it sends one
new Connection ID in the event of config rotation Section 3.1. Doing
so might falsely suggest to the client that said CIDs were generated
in a secure fashion.
A linkability attack would find some means of determining that two
connection IDs route to the same server. As described above, there
is no scheme that strictly prevents linkability for all traffic
patterns, and therefore efforts to frustrate any analysis of server
ID encoding have diminishing returns.
11.1. Attackers not between the load balancer and server
Any attacker might open a connection to the server infrastructure and
aggressively simulate migration to obtain a large sample of IDs that
map to the same server. It could then apply analytical techniques to
try to obtain the server encoding.
The Stream and Block Cipher CID algorithms provide robust protection
against any sort of linkage. The Plaintext CID algorithm makes no
attempt to protect this encoding.
Were this analysis to obtain the server encoding, then on-path
observers might apply this analysis to correlating different client
IP addresses.
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11.2. Attackers between the load balancer and server
Attackers in this privileged position are intrinsically able to map
two connection IDs to the same server. The QUIC-LB algorithms do
prevent the linkage of two connection IDs to the same individual
connection if servers make reasonable selections when generating new
IDs for that connection.
11.3. Multiple Configuration IDs
During the period in which there are multiple deployed configuration
IDs (see Section 3.1), there is a slight increase in linkability.
The server space is effectively divided into segments with CIDs that
have different config rotation bits. Entities that manage servers
SHOULD strive to minimize these periods by quickly deploying new
configurations across the server pool.
11.4. Limited configuration scope
A simple deployment of QUIC-LB in a cloud provider might use the same
global QUIC-LB configuration across all its load balancers that route
to customer servers. An attacker could then simply become a
customer, obtain the configuration, and then extract server IDs of
other customers' connections at will.
To avoid this, the configuration agent SHOULD issue QUIC-LB
configurations to mutually distrustful servers that have different
keys for encryption algorithms. In many cases, the load balancers
can distinguish these configurations by external IP address.
However, assigning multiple entities to an IP address is
complimentary with concealing DNS requests (e.g., DoH [RFC8484]) and
the TLS Server Name Indicator (SNI) ([I-D.ietf-tls-esni]) to obscure
the ultimate destination of traffic. While the load balancer's
fallback algorithm (Section 4.2) can use the SNI to make a routing
decision on the first packet, there are three ways to route
subsequent packets:
* all co-tenants can use the same QUIC-LB configuration, leaking the
server mapping to each other as described above;
* co-tenants can be issued one of up to three configurations
distinguished by the config rotation bits (Section 3.1), exposing
information about the target domain to the entire network; or
* tenants can use 4-tuple routing in their CIDs (in which case they
SHOULD disable migration in their connections), which neutralizes
the value of QUIC-LB but preserves privacy.
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When configuring QUIC-LB, administrators must evaluate the privacy
tradeoff considering the relative value of each of these properties,
given the trust model between tenants, the presence of methods to
obscure the domain name, and value of address migration in the tenant
use cases.
As the plaintext algorithm makes no attempt to conceal the server
mapping, these deployments SHOULD simply use a common configuration.
11.5. Stateless Reset Oracle
Section 21.9 of [RFC9000] discusses the Stateless Reset Oracle
attack. For a server deployment to be vulnerable, an attacking
client must be able to cause two packets with the same Destination
CID to arrive at two different servers that share the same
cryptographic context for Stateless Reset tokens. As QUIC-LB
requires deterministic routing of DCIDs over the life of a
connection, it is a sufficient means of avoiding an Oracle without
additional measures.
Note also that when a server starts using a new QUIC-LB config
rotation codepoint, new CIDs might not be unique with respect to
previous configurations that occupied that codepoint, and therefore
different clients may have observed the same CID and stateless reset
token. A straightforward method of managing stateless reset keys is
to maintain a separate key for each config rotation codepoint, and
replace each key when the configuration for that codepoint changes.
Thus, a server transitions from one config to another, it will be
able to generate correct tokens for connections using either type of
CID.
11.6. Connection ID Entropy
If a server ever reuses a nonce in generating a CID for a given
configuration, it risks exposing sensitive information. Given the
same server ID, the CID will be identical (aside from a possible
difference in the first octet). This can risk exposure of the QUIC-
LB key. If two clients receive the same connection ID, they also
have each other's stateless reset token unless that key has changed
in the interim.
The Stream Cipher and Block Cipher algorithms need to generate
different cipher text for each generated Connection ID instance to
protect the Server ID. To do so, at least four octets of the CID are
reserved for a nonce that, if used only once, will result in unique
cipher text for each Connection ID.
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If servers simply increment the nonce by one with each generated
connection ID, then it is safe to use the existing keys until any
server's nonce counter exhausts the allocated space and rolls over to
zero. Whether or not it implements this method, the server MUST NOT
reuse a nonce until it switches to a configuration with new keys.
Both the Plaintext CID and Block Cipher CID algorithms send parts of
their nonce in plaintext. Servers MUST generate nonces so that the
plaintext portion appears to be random. Observable correlations
between plaintext nonces would provide trivial linkability between
individual connections, rather than just to a common server.
For any algorithm, configuration agents SHOULD implement an out-of-
band method to discover when servers are in danger of exhausting
their nonce space, and SHOULD respond by issuing a new configuration.
A server that has exhausted its nonces MUST either switch to a
different configuration, or if none exists, use the 4-tuple routing
config rotation codepoint.
When sizing a nonce that is to be randomly generated, the
configuration agent SHOULD consider that a server generating a N-bit
nonce will create a duplicate about every 2^(N/2) attempts, and
therefore compare the expected rate at which servers will generate
CIDs with the lifetime of a configuration.
11.7. Shared-State Retry Keys
The Shared-State Retry Service defined in Section 7.3 describes the
format of retry tokens or new tokens protected and encrypted using
AES128-GCM. Each token includes a 96 bit randomly generated unique
token number, and an 8 bit identifier used to get the AES-GCM
encryption context. The AES-GCM encryption context contains a 128
bit key and an AEAD IV. There are three important security
considerations for these tokens:
* An attacker that obtains a copy of the encryption key will be able
to decrypt and forge tokens.
* Attackers may be able to retrieve the key if they capture a
sufficently large number of retry tokens encrypted with a given
key.
* Confidentiality of the token data will fail if separate tokens
reuse the same 96 bit unique token number and the same key.
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To protect against disclosure of keys to attackers, service and
servers MUST ensure that the keys are stored securely. To limit the
consequences of potential exposures, the time to live of any given
key should be limited.
Section 6.6 of [RFC9001] states that "Endpoints MUST count the number
of encrypted packets for each set of keys. If the total number of
encrypted packets with the same key exceeds the confidentiality limit
for the selected AEAD, the endpoint MUST stop using those keys." It
goes on with the specific limit: "For AEAD_AES_128_GCM and
AEAD_AES_256_GCM, the confidentiality limit is 2^23 encrypted
packets; see Appendix B.1." It is prudent to adopt the same limit
here, and configure the service in such a way that no more than 2^23
tokens are generated with the same key.
In order to protect against collisions, the 96 bit unique token
numbers should be generated using a cryptographically secure
pseudorandom number generator (CSPRNG), as specified in Appendix C.1
of the TLS 1.3 specification [RFC8446]. With proper random numbers,
if fewer than 2^40 tokens are generated with a single key, the risk
of collisions is lower than 0.001%.
12. IANA Considerations
There are no IANA requirements.
13. References
13.1. Normative References
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8999] Thomson, M., "Version-Independent Properties of QUIC",
RFC 8999, DOI 10.17487/RFC8999, May 2021,
<https://www.rfc-editor.org/info/rfc8999>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/info/rfc9000>.
[TIME_T] "Open Group Standard: Vol. 1: Base Definitions, Issue 7",
IEEE Std 1003.1 , 2018,
<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
V1_chap04.html#tag_04_16>.
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13.2. Informative References
[I-D.draft-ietf-tls-dtls13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
dtls13-43, 30 April 2021,
<https://www.ietf.org/archive/id/draft-ietf-tls-
dtls13-43.txt>.
[I-D.ietf-tls-dtls-connection-id]
Rescorla, E., Tschofenig, H., Fossati, T., and A. Kraus,
"Connection Identifiers for DTLS 1.2", Work in Progress,
Internet-Draft, draft-ietf-tls-dtls-connection-id-13, 22
June 2021, <https://www.ietf.org/archive/id/draft-ietf-
tls-dtls-connection-id-13.txt>.
[I-D.ietf-tls-esni]
Rescorla, E., Oku, K., Sullivan, N., and C. A. Wood, "TLS
Encrypted Client Hello", Work in Progress, Internet-Draft,
draft-ietf-tls-esni-13, 12 August 2021,
<https://www.ietf.org/archive/id/draft-ietf-tls-esni-
13.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4106] Viega, J. and D. McGrew, "The Use of Galois/Counter Mode
(GCM) in IPsec Encapsulating Security Payload (ESP)",
RFC 4106, DOI 10.17487/RFC4106, June 2005,
<https://www.rfc-editor.org/info/rfc4106>.
[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security", RFC 4347, DOI 10.17487/RFC4347, April 2006,
<https://www.rfc-editor.org/info/rfc4347>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
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[RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm
Agility and Selecting Mandatory-to-Implement Algorithms",
BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015,
<https://www.rfc-editor.org/info/rfc7696>.
[RFC7983] Petit-Huguenin, M. and G. Salgueiro, "Multiplexing Scheme
Updates for Secure Real-time Transport Protocol (SRTP)
Extension for Datagram Transport Layer Security (DTLS)",
RFC 7983, DOI 10.17487/RFC7983, September 2016,
<https://www.rfc-editor.org/info/rfc7983>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8484] Hoffman, P. and P. McManus, "DNS Queries over HTTPS
(DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
<https://www.rfc-editor.org/info/rfc8484>.
[RFC9001] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure
QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021,
<https://www.rfc-editor.org/info/rfc9001>.
Appendix A. QUIC-LB YANG Model
This YANG model conforms to [RFC6020] and expresses a complete QUIC-
LB configuration.
module ietf-quic-lb {
yang-version "1.1";
namespace "urn:ietf:params:xml:ns:yang:ietf-quic-lb";
prefix "quic-lb";
import ietf-yang-types {
prefix yang;
reference
"RFC 6991: Common YANG Data Types.";
}
import ietf-inet-types {
prefix inet;
reference
"RFC 6991: Common YANG Data Types.";
}
organization
"IETF QUIC Working Group";
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contact
"WG Web: <http://datatracker.ietf.org/wg/quic>
WG List: <quic@ietf.org>
Authors: Martin Duke (martin.h.duke at gmail dot com)
Nick Banks (nibanks at microsoft dot com)";
description
"This module enables the explicit cooperation of QUIC servers with
trusted intermediaries without breaking important protocol features.
Copyright (c) 2021 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject to
the license terms contained in, the Simplified BSD License set
forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX
(https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL
NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'NOT RECOMMENDED',
'MAY', and 'OPTIONAL' in this document are to be interpreted as
described in BCP 14 (RFC 2119) (RFC 8174) when, and only when,
they appear in all capitals, as shown here.";
revision "2021-01-29" {
description
"Initial Version";
reference
"RFC XXXX, QUIC-LB: Generating Routable QUIC Connection IDs";
}
container quic-lb {
presence "The container for QUIC-LB configuration.";
description
"QUIC-LB container.";
typedef quic-lb-key {
type yang:hex-string {
length 47;
}
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description
"This is a 16-byte key, represented with 47 bytes";
}
typedef algorithm-type {
type enumeration {
enum plaintext {
description "Plaintext CID Algorithm";
}
enum stream-cipher {
description "Stream Cipher CID Algorithm";
}
enum block-cipher {
description "Block Cipher CID Algorithm";
}
}
}
list cid-configs {
key "config-rotation-bits";
description
"List up to three load balancer configurations";
leaf config-rotation-bits {
type uint8 {
range "0..2";
}
mandatory true;
description
"Identifier for this CID configuration.";
}
leaf first-octet-encodes-cid-length {
type boolean;
default false;
description
"If true, the six least significant bits of the first CID
octet encode the CID length minus one.";
}
leaf cid-key {
type quic-lb-key;
description
"Key for encrypting the connection ID. If absent, the
configuration uses the Plaintext algorithm.";
}
leaf algorithm {
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type algorithm-type;
mandatory true;
description
"The algorithm that encodes the server ID";
}
must 'cid-key or (algorithm = "plaintext")' {
error-message "Encrypted algorithm requires key";
}
leaf nonce-length {
type uint8 {
range "4..18";
}
mandatory true;
description
"Length, in octets, of the nonce. Short nonces mean there will be
frequent configuration updates.";
}
leaf server-id-length {
type uint8 {
range "1..15";
}
must '. <= (19 - ../nonce-length)' {
error-message
"Server ID and nonce lengths must sum to no more than 19.";
}
must '(../algorithm != "block-cipher") or (. <= 12)' {
error-message
"block-cipher requires server ID length <= 12.";
}
must '(../algorithm != "block-cipher") or
((. + ../nonce-length) >= 16)' {
error-message
"For Block cipher, server ID length plus nonce length must be at
least 16";
}
mandatory true;
description
"Length (in octets) of a server ID. Further range-limited
by sid-allocation, cid-key, and nonce-length.";
}
list server-id-mappings {
key "server-id";
description "Statically allocated Server IDs";
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leaf server-id {
type yang:hex-string;
must "string-length(.) = 3 * ../../server-id-length - 1";
mandatory true;
description
"An allocated server ID";
}
leaf server-address {
type inet:ip-address;
mandatory true;
description
"Destination address corresponding to the server ID";
}
}
}
container retry-service-config {
description
"Configuration of Retry Service. If supported-versions is empty, there
is no retry service. If token-keys is empty, it uses the non-shared-
state service. If present, it uses shared-state tokens.";
leaf-list supported-versions {
type uint32;
description
"QUIC versions that the retry service supports. If empty, there
is no retry service.";
}
leaf unsupported-version-default {
type enumeration {
enum allow {
description "Unsupported versions admitted by default";
}
enum deny {
description "Unsupported versions denied by default";
}
}
default allow;
description
"Are unsupported versions not in version-exceptions allowed
or denied?";
}
leaf-list version-exceptions {
type uint32;
description
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"Exceptions to the default-deny or default-allow rule.";
}
list token-keys {
key "key-sequence-number";
description
"list of active keys, for key rotation purposes. Existence implies
shared-state format";
leaf key-sequence-number {
type uint8 {
range "0..127";
}
mandatory true;
description
"Identifies the key used to encrypt the token";
}
leaf token-key {
type quic-lb-key;
mandatory true;
description
"16-byte key to encrypt the token";
}
leaf token-iv {
type yang:hex-string {
length 23;
}
mandatory true;
description
"8-byte IV to encrypt the token, encoded in 23 bytes";
}
}
}
}
}
A.1. Tree Diagram
This summary of the YANG model uses the notation in [RFC8340].
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module: ietf-quic-lb
+--rw quic-lb
+--rw cid-configs* [config-rotation-bits]
| +--rw config-rotation-bits uint8
| +--rw first-octet-encodes-cid-length? boolean
| +--rw cid-key? quic-lb-key
| +--rw algorithm algorithm-tyype
| +--rw nonce-length uint8
| +--rw server-id-length uint8
| +--rw server-id-mappings* [server-id]
| | +--rw server-id yang:hex-string
| | +--rw server-address inet:ip-address
+--ro retry-service-config
| +--rw supported-versions* uint32
| +--rw unsupported-version-default? enumeration
| +--rw version-exceptions* uint32
| +--rw token-keys*? [key-sequence-number]
| | +--rw key-sequence-number uint8
| | +--rw token-key quic-lb-key
| | +--rw token-iv yang:hex-string
Appendix B. Load Balancer Test Vectors
Each section of this draft includes multiple sets of load balancer
configuration, each of which has five examples of server ID and
server use bytes and how they are encoded in a CID.
In some cases, there are no server use bytes. Note that, for
simplicity, the first octet bits used for neither config rotation nor
length self-encoding are random, rather than listed in the server use
field. Therefore, a server implementation using these parameters may
generate CIDs with a slightly different first octet.
This section uses the following abbreviations:
cid Connection ID
cr_bits Config Rotation Bits
LB Load Balancer
sid Server ID
sid_len Server ID length
All values except length_self_encoding and sid_len are expressed in
hexidecimal format.
B.1. Plaintext Connection ID Algorithm
TBD
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B.2. Stream Cipher Connection ID Algorithm
In each case below, the server is using a plain text nonce value of
zero.
TBD
B.3. Block Cipher Connection ID Algorithm
In each case below, the server is using a plain text nonce value of
zero.
TBD
B.4. Shared State Retry Tokens
In this case, the shared-state retry token is issued by retry
service, so the opaque data of shared-state retry token body would be
null (Section 7.3).
LB configuration:
key_seq 0x00
encrypt_key 0x30313233343536373839303132333435
AEAD_IV 0x313233343536373839303132
Shared-State Retry Service Token Body:
ODCIL 0x12
RSCIL 0x10
port 0x1a0a
original_destination_connection_id 0x0c3817b544ca1c94313bba41757547eec937
retry_source_connection_id 0x0301e770d24b3b13070dd5c2a9264307
timestamp 0x0000000060c7bf4d
Shared-State Retry Service Token:
unique_token_number 0x59ef316b70575e793e1a8782
key_sequence 0x00
encrypted_shared_state_retry_service_token_body
0x7d38b274aa4427c7a1557c3fa666945931defc65da387a83855196a7cb73caac1e28e5346fd76868de94f8b62294
AEAD_ICV 0xf91174fdd711543a32d5e959867f9c22
AEAD related parameters:
client_ip_addr 127.0.0.1
client_port 6666
AEAD_nonce 0x68dd025f45616941072ab6b0
AEAD_associated_data 0x7f00000100000000000000000000000059ef316b70575e793e1a878200
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Appendix C. Interoperability with DTLS over UDP
Some environments may contain DTLS traffic as well as QUIC operating
over UDP, which may be hard to distinguish.
In most cases, the packet parsing rules above will cause a QUIC-LB
load balancer to route DTLS traffic in an appropriate way. DTLS 1.3
implementations that use the connection_id extension
[I-D.ietf-tls-dtls-connection-id] might use the techniques in this
document to generate connection IDs and achieve robust routability
for DTLS associations if they meet a few additional requirements.
This non-normative appendix describes this interaction.
C.1. DTLS 1.0 and 1.2
DTLS 1.0 [RFC4347] and 1.2 [RFC6347] use packet formats that a QUIC-
LB router will interpret as short header packets with CIDs that
request 4-tuple routing. As such, they will route such packets
consistently as long as the 4-tuple does not change. Note that DTLS
1.0 has been deprecated by the IETF.
The first octet of every DTLS 1.0 or 1.2 datagram contains the
content type. A QUIC-LB load balancer will interpret any content
type less than 128 as a short header packet, meaning that the
subsequent octets should contain a connection ID.
Existing TLS content types comfortably fit in the range below 128.
Assignment of codepoints greater than 64 would require coordination
in accordance with [RFC7983], and anyway would likely create problems
demultiplexing DTLS and version 1 of QUIC. Therefore, this document
believes it is extremely unlikely that TLS content types of 128 or
greater will be assigned. Nevertheless, such an assignment would
cause a QUIC-LB load balancer to interpret the packet as a QUIC long
header with an essentially random connection ID, which is likely to
be routed irregularly.
The second octet of every DTLS 1.0 or 1.2 datagram is the bitwise
complement of the DTLS Major version (i.e. version 1.x = 0xfe). A
QUIC-LB load balancer will interpret this as a connection ID that
requires 4-tuple based load balancing, meaning that the routing will
be consistent as long as the 4-tuple remains the same.
[I-D.ietf-tls-dtls-connection-id] defines an extension to add
connection IDs to DTLS 1.2. Unfortunately, a QUIC-LB load balancer
will not correctly parse the connection ID and will continue 4-tuple
routing. An modified QUIC-LB load balancer that correctly identifies
DTLS and parses a DTLS 1.2 datagram for the connection ID is outside
the scope of this document.
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C.2. DTLS 1.3
DTLS 1.3 [I-D.draft-ietf-tls-dtls13] changes the structure of
datagram headers in relevant ways.
Handshake packets continue to have a TLS content type in the first
octet and 0xfe in the second octet, so they will be 4-tuple routed,
which should not present problems for likely NAT rebinding or address
change events.
Non-handshake packets always have zero in their most significant bit
and will therefore always be treated as QUIC short headers. If the
connection ID is present, it follows in the succeeding octets.
Therefore, a DTLS 1.3 association where the server utilizes
Connection IDs and the encodings in this document will be routed
correctly in the presence of client address and port changes.
However, if the client does not include the connection_id extension
in its ClientHello, the server is unable to use connection IDs. In
this case, non- handshake packets will appear to contain random
connection IDs and be routed randomly. Thus, unmodified QUIC-LB load
balancers will not work with DTLS 1.3 if the client does not
advertise support for connection IDs, or the server does not request
the use of a compliant connection ID.
A QUIC-LB load balancer might be modified to identify DTLS 1.3
packets and correctly parse the fields to identify when there is no
connection ID and revert to 4-tuple routing, removing the server
requirement above. However, such a modification is outside the scope
of this document, and classifying some packets as DTLS might be
incompatible with future versions of QUIC.
C.3. Future Versions of DTLS
As DTLS does not have an IETF consensus document that defines what
parts of DTLS will be invariant in future versions, it is difficult
to speculate about the applicability of this section to future
versions of DTLS.
Appendix D. Acknowledgments
The authors would like to thank Christian Huitema and Ian Swett for
their major design contributions.
Manasi Deval, Erik Fuller, Toma Gavrichenkov, Jana Iyengar, Subodh
Iyengar, Ladislav Lhotka, Jan Lindblad, Ling Tao Nju, Kazuho Oku,
Udip Pant, Martin Thomson, Dmitri Tikhonov, Victor Vasiliev, and
William Zeng Ke all provided useful input to this document.
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Appendix E. Change Log
*RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document.
E.1. since draft-ietf-quic-load-balancers-08
* Eliminate Dynamic SID allocation
* Eliminated server use bytes
E.2. since draft-ietf-quic-load-balancers-07
* Shortened SSCID nonce minimum length to 4 bytes
* Removed RSCID from Retry token body
* Simplified CID formats
* Shrunk size of SID table
E.3. since draft-ietf-quic-load-balancers-06
* Added interoperability with DTLS
* Changed "non-compliant" to "unroutable"
* Changed "arbitrary" algorithm to "fallback"
* Revised security considerations for mistrustful tenants
* Added retry service considerations for non-Initial packets
E.4. since draft-ietf-quic-load-balancers-05
* Added low-config CID for further discussion
* Complete revision of shared-state Retry Token
* Added YANG model
* Updated configuration limits to ensure CID entropy
* Switched to notation from quic-transport
E.5. since draft-ietf-quic-load-balancers-04
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* Rearranged the shared-state retry token to simplify token
processing
* More compact timestamp in shared-state retry token
* Revised server requirements for shared-state retries
* Eliminated zero padding from the test vectors
* Added server use bytes to the test vectors
* Additional compliant DCID criteria
E.6. since-draft-ietf-quic-load-balancers-03
* Improved Config Rotation text
* Added stream cipher test vectors
* Deleted the Obfuscated CID algorithm
E.7. since-draft-ietf-quic-load-balancers-02
* Replaced stream cipher algorithm with three-pass version
* Updated Retry format to encode info for required TPs
* Added discussion of version invariance
* Cleaned up text about config rotation
* Added Reset Oracle and limited configuration considerations
* Allow dropped long-header packets for known QUIC versions
E.8. since-draft-ietf-quic-load-balancers-01
* Test vectors for load balancer decoding
* Deleted remnants of in-band protocol
* Light edit of Retry Services section
* Discussed load balancer chains
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E.9. since-draft-ietf-quic-load-balancers-00
* Removed in-band protocol from the document
E.10. Since draft-duke-quic-load-balancers-06
* Switch to IETF WG draft.
E.11. Since draft-duke-quic-load-balancers-05
* Editorial changes
* Made load balancer behavior independent of QUIC version
* Got rid of token in stream cipher encoding, because server might
not have it
* Defined "non-compliant DCID" and specified rules for handling
them.
* Added psuedocode for config schema
E.12. Since draft-duke-quic-load-balancers-04
* Added standard for retry services
E.13. Since draft-duke-quic-load-balancers-03
* Renamed Plaintext CID algorithm as Obfuscated CID
* Added new Plaintext CID algorithm
* Updated to allow 20B CIDs
* Added self-encoding of CID length
E.14. Since draft-duke-quic-load-balancers-02
* Added Config Rotation
* Added failover mode
* Tweaks to existing CID algorithms
* Added Block Cipher CID algorithm
* Reformatted QUIC-LB packets
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E.15. Since draft-duke-quic-load-balancers-01
* Complete rewrite
* Supports multiple security levels
* Lightweight messages
E.16. Since draft-duke-quic-load-balancers-00
* Converted to markdown
* Added variable length connection IDs
Authors' Addresses
Martin Duke
F5 Networks, Inc.
Email: martin.h.duke@gmail.com
Nick Banks
Microsoft
Email: nibanks@microsoft.com
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