| DOTS | M. Boucadair, Ed. |
| Internet-Draft | Orange |
| Intended status: Standards Track | T. Reddy, Ed. |
| Expires: January 4, 2020 | McAfee |
| July 03, 2019 |
Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel Specification
draft-ietf-dots-data-channel-30
The document specifies a Distributed Denial-of-Service Open Threat Signaling (DOTS) data channel used for bulk exchange of data that cannot easily or appropriately communicated through the DOTS signal channel under attack conditions.
This is a companion document to the DOTS signal channel specification.
Please update these statements within the document with the RFC number to be assigned to this document:
Please update the "revision" date of the YANG module.
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."
This Internet-Draft will expire on January 4, 2020.
Copyright (c) 2019 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 extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
A distributed denial-of-service (DDoS) attack is an attempt to make machines or network resources unavailable to their intended users. In most cases, sufficient scale can be achieved by compromising enough end-hosts and using those infected hosts to perpetrate and amplify the attack. The victim of such attack can be an application server, a router, a firewall, an entire network, etc.
+---------------+ +---------------+ | | <------- Signal Channel ------> | | | DOTS Client | | DOTS Server | | | <======= Data Channel ======> | | +---------------+ +---------------+
Figure 1: DOTS Channels
As discussed in [RFC8612], the lack of a common method to coordinate a real-time response among involved actors and network domains inhibits the speed and effectiveness of DDoS attack mitigation. From that standpoint, DDoS Open Threat Signaling (DOTS) defines an architecture that allows a DOTS client to send requests to a DOTS server for DDoS attack mitigation [I-D.ietf-dots-architecture]. The DOTS approach is thus meant to minimize the impact of DDoS attacks, thereby contributing to the enforcement of more efficient defensive if not proactive security strategies. To that aim, DOTS defines two channels: the signal and the data channels (Figure 1).
The DOTS signal channel is used to carry information about a device or a network (or a part thereof) that is under a DDoS attack. Such information is sent by a DOTS client to an upstream DOTS server so that appropriate mitigation actions are undertaken on traffic deemed suspicious. The DOTS signal channel is further elaborated in [I-D.ietf-dots-signal-channel].
As for the DOTS data channel, it is used for infrequent bulk data exchange between DOTS agents to significantly improve the coordination of all the parties involved in the response to the attack. Section 2 of [I-D.ietf-dots-architecture] mentions that the DOTS data channel is used to perform the following tasks:
Refer to
Section 7 for more details.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 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
The reader should be familiar with the terms defined in [RFC8612].
The terminology for describing YANG modules is defined in [RFC7950]. The meaning of the symbols in the tree diagrams is defined in [RFC8340].
This document generalizes the notion of Access Control List (ACL) so that it is not device-specific [RFC8519]. As such, this document defines an ACL as an ordered set of rules that is used to filter traffic. Each rule is represented by an Access Control Entry (ACE). ACLs communicated via the DOTS data channel are not bound to a device interface.
For the sake of simplicity, all of the examples in this document use "/restconf" as the discovered RESTCONF API root path. Many protocol header lines and message-body text within examples throughout the document are split into multiple lines for display purposes only. When a line ends with backslash ('\') as the last character, the line is wrapped for display purposes. It is to be considered to be joined to the next line by deleting the backslash, the following line break, and the leading whitespace of the next line.
Unlike the DOTS signal channel, which must remain operational even when confronted with signal degradation due to packets loss, the DOTS data channel is not expected to be fully operational at all times, especially when a DDoS attack is underway. The requirements for a DOTS data channel protocol are documented in [RFC8612].
This specification does not require an order of DOTS signal and data channel creations nor mandates a time interval between them. These considerations are implementation- and deployment-specific.
As the primary function of the data channel is data exchange, a reliable transport mode is required in order for DOTS agents to detect data delivery success or failure. This document uses RESTCONF [RFC8040] over TLS over TCP as the DOTS data channel protocol. The abstract layering of DOTS data channel is shown in Figure 2.
+-------------------+ | DOTS Data Channel | +-------------------+ | RESTCONF | +-------------------+ | TLS | +-------------------+ | TCP | +-------------------+ | IP | +-------------------+
Figure 2: Abstract Layering of DOTS Data Channel
The HTTP POST, PUT, PATCH, and DELETE methods are used to edit data resources represented by DOTS data channel YANG modules. These basic edit operations allow the DOTS data channel running configuration to be altered by a DOTS client. Rules for generating and processing RESTCONF methods are defined in Section 4 of [RFC8040].
DOTS data channel configuration information as well as state information can be retrieved with the GET method. An HTTP status-line is returned for each request to report success or failure for RESTCONF operations (Section 5.4 of [RFC8040]). The "error-tag" provides more information about encountered errors (Section 7 of [RFC8040]).
DOTS clients perform the root resource discovery procedure discussed in Section 3.1 of [RFC8040] to determine the root of the RESTCONF API. After discovering the RESTCONF API root, a DOTS client uses this value as the initial part of the path in the request URI in any subsequent request to the DOTS server. The DOTS server may support the retrieval of the YANG modules it supports (Section 3.7 in [RFC8040]). For example, a DOTS client may use RESTCONF to retrieve the vendor-specific YANG modules supported by its DOTS server.
JavaScript Object Notation (JSON) [RFC8259] payloads are used to propagate the DOTS data-channel-specific payload messages that carry request parameters and response information, such as errors. This specification uses the encoding rules defined in [RFC7951] for representing DOTS data channel configuration data using YANG (Section 4) as JSON text.
A DOTS client registers itself to its DOTS server(s) in order to set up DOTS data channel-related configuration data and receive state data (i.e., non-configuration data) from the DOTS server(s) (Section 5). Mutual authentication considerations are specified in Section 8 of [I-D.ietf-dots-signal-channel]. The coupling of signal and data channels is discussed in Section 4.4.1 of [I-D.ietf-dots-signal-channel].
A DOTS client can either maintain a persistent connection or periodic connections with its DOTS server(s). If the DOTS client needs to frequently update the drop-list or accept-list filtering rules or aliases, it maintains a persistent connection with the DOTS server. For example, CAPTCHA and cryptographic puzzles can be used by the mitigation service in the DOTS client domain to determine whether the IP address is used for legitimate purpose or not, and the DOTS client can frequently update the drop-list filtering rules. A persistent connection is also useful if the DOTS client subscribes to event notifications (Section 6.3 of [RFC8040]).
A single DOTS data channel between DOTS agents can be used to exchange multiple requests and multiple responses. To reduce DOTS client and DOTS server workload, DOTS clients SHOULD re-use the same TLS session. While the communication to the DOTS server is quiescent, the DOTS client MAY probe the server to ensure it has maintained cryptographic state. Such probes can also keep alive firewall and/or NAT bindings. A TLS heartbeat [RFC6520] verifies that the DOTS server still has TLS state by returning a TLS message.
A DOTS server may detect conflicting filtering requests from distinct DOTS clients which belong to the same domain. For example, a DOTS client could request to drop-list a prefix by specifying the source prefix, while another DOTS client could request to accept-list that same source prefix, but both having the same destination prefix. DOTS servers SHOULD support a configuration parameter to indicate the behavior to follow when a conflict is detected (e.g., reject all, reject the new request, notify an administrator for validation). Section 7.2 specifies a default behavior when no instruction is supplied to a DOTS server.
How a DOTS client synchronizes its configuration with the one maintained by its DOTS server(s) is implementation-specific. For example:
NAT considerations for the DOTS data channel are similar to those discussed in Section 3 of [I-D.ietf-dots-signal-channel].
How filtering rules that are instantiated on a DOTS server are translated into network configurations actions is out of scope of this specification.
Some of the fields introduced in Section 4 are also discussed in Sections 5, 6, and 7. These sections are authoritative for these fields.
This document assumes that DOTS clients are provisioned with a way to know how to reach their DOTS server(s), which could occur by a variety of means (e.g., local configuration, or dynamic means such as DHCP [I-D.ietf-dots-server-discovery]). The specification of such means are out of scope of this document.
Likewise, it is out of scope of this document to specify the behavior to be followed by a DOTS client to send DOTS requests when multiple DOTS servers are provisioned (e.g., contact all DOTS servers, select one DOTS server among the list).
When a server-domain DOTS gateway is involved in DOTS data channel exchanges, the same considerations for manipulating the 'cdid' (client domain identifier) parameter specified in [I-D.ietf-dots-signal-channel] MUST be followed by DOTS agents. As a reminder, 'cdid' is meant to assist the DOTS server to enforce some policies (e.g., limit the number of filtering rules per DOTS client or per DOTS client domain). A loop detect mechanism for DOTS gateways is specified in Section 3.4.
If a DOTS gateway is involved, the DOTS gateway verifies that the DOTS client is authorized to undertake a data channel action (e.g., instantiate filtering rules). If the DOTS client is authorized, it propagates the rules to the upstream DOTS server. Likewise, the DOTS server verifies that the DOTS gateway is authorized to relay data channel actions. For example, to create or purge filters, a DOTS client sends its request to its DOTS gateway. The DOTS gateway validates the rules in the request and proxies the requests containing the filtering rules to its DOTS server. When the DOTS gateway receives the associated response from the DOTS server, it propagates the response back to the DOTS client.
error-app-tag: loop-detected
error-tag: operation-failed
error-type: transport, application
error-info: <via-header> : A copy of the Via header field when
the loop was detected.
Description: An infinite loop has been detected when forwarding
a requests via a proxy.
Figure 3: Loop Detected Error
In order to detect and prevent infinite loops, DOTS gateways MUST support the procedure defined in Section 5.7.1 of [RFC7230]. In particular, each intermediate DOTS gateway MUST check that none of its own information (e.g., server names, literal IP addresses) is present in the "Via" header field of a DOTS message it receives:
Unless configured otherwise, DOTS gateways at the boundaries of a DOTS client domain SHOULD remove the previous "Via" header field information after checking for a loop before forwarding. This behavior is required for topology hiding purposes but can also serve to minimize potential conflicts that may arise if overlapping information is used in distinct DOTS domains (e.g., private IPv4 addresses, non globally unique aliases).
In order to avoid stale entries, a lifetime is associated with alias and filtering entries created by DOTS clients. Also, DOTS servers may track the inactivity timeout of DOTS clients to detect stale entries.
The DOTS data channel YANG module (ietf-dots-data-channel) provides a method for DOTS clients to manage aliases for resources for which mitigation may be requested. Such aliases may be used in subsequent DOTS signal channel exchanges to refer more efficiently to the resources under attack.
Note that the full module's tree has been split across several figures to aid the exposition of the various sub-trees.
The tree structure for the DOTS alias is depicted in Figure 4.
module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| +--rw cuid string
| +--rw cdid? string
| +--rw aliases
| | +--rw alias* [name]
| | +--rw name string
| | +--rw target-prefix* inet:ip-prefix
| | +--rw target-port-range* [lower-port]
| | | +--rw lower-port inet:port-number
| | | +--rw upper-port? inet:port-number
| | +--rw target-protocol* uint8
| | +--rw target-fqdn* inet:domain-name
| | +--rw target-uri* inet:uri
| | +--ro pending-lifetime? int32
| +--rw acls
| ...
+--ro capabilities
...
Figure 4: DOTS Alias Subtree
Also, the 'ietf-dots-data-channel' module provides a method for DOTS clients to manage filtering rules. Examples of filtering management in a DOTS context include, but not limited to:
The tree structure for the DOTS filtering entries is depicted in Figure 5.
Investigations into the prospect of augmenting 'ietf-access-control-list' to meet DOTS requirements concluded that such a design approach did not support many of the DOTS requirements, e.g.,
Accordingly, new DOTS filtering entries (i.e., Access Control List (ACL)) are defined that mimic the structure specified in [RFC8519]. Concretely, DOTS agents are assumed to manipulate an ordered list of ACLs; each ACL contains a separately ordered list of Access Control Entries (ACEs). Each ACE has a group of match and a group of action criteria.
Once all the ACE entries have been iterated though with no match, then all the following ACL's ACE entries are iterated through until the first match at which point the specified action is applied. If there is no match during 'idle' time (i.e., no mitigation is active), then there is no further action to be taken against the packet. If there is no match during active mitigation, then the packet will still be scrubbed by the DDoS mitigator.
module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| +--rw cuid string
| +--rw cdid? string
| +--rw aliases
| | ...
| +--rw acls
| +--rw acl* [name]
| +--rw name string
| +--rw type? ietf-acl:acl-type
| +--rw activation-type? activation-type
| +--ro pending-lifetime? int32
| +--rw aces
| +--rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | +--:(ipv4)
| | | | ...
| | | +--:(ipv6)
| | | ...
| | +--rw (l4)?
| | +--:(tcp)
| | | ...
| | +--:(udp)
| | | ...
| | +--:(icmp)
| | ...
| +--rw actions
| | +--rw forwarding identityref
| | +--rw rate-limit? decimal64
| +--ro statistics
| +--ro matched-packets? yang:counter64
| +--ro matched-octets? yang:counter64
+--ro capabilities
...
Figure 5: DOTS ACLs Subtree
Filtering rules instructed by a DOTS client assumes a default direction: the destination is the DOTS client domain.
DOTS forwarding actions can be 'accept' (i.e., accept matching traffic) or 'drop' (i.e., drop matching traffic without sending any ICMP error message). Accepted traffic can be subject to rate-limiting 'rate-limit'. Note that 'reject' action (i.e., drop matching traffic and send an ICMP error message to the source) is not supported in 'ietf-dots-data-channel' because it is not appropriate in the context of DDoS mitigation. Generating ICMP messages to notify drops when mitigating a DDoS attack will exacerbate the DDoS attack. Furthermore, these ICMP messages will be used by an attacker as an explicit signal that the traffic is being blocked.
The 'ietf-dots-data-channel' module reuses the packet fields module 'ietf-packet-fields' [RFC8519] which defines matching on fields in the packet including IPv4, IPv6, and transport layer fields. The 'ietf-dots-data-channel' module can be augmented, for example, to support additional protocol-specific matching fields.
This specification defines a new IPv4/IPv6 matching field called 'fragment' to efficiently handle fragment-related filtering rules. Indeed, [RFC8519] does not support such capability for IPv6 but offers a partial support for IPv4 by means of 'flags'. Nevertheless, the use of 'flags' is problematic since it does not allow to define a bitmask. For example, setting other bits not covered by the 'flags' filtering clause in a packet will allow that packet to get through (because it won't match the ACE). Sample examples to illustrate how 'fragment' can be used are provided in Appendix A.
Figure 6 shows the IPv4 match subtree.
module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| ...
| +--rw acls
| +--rw acl* [name]
| ...
| +--rw aces
| +--rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | +--:(ipv4)
| | | | +--rw ipv4
| | | | +--rw dscp? inet:dscp
| | | | +--rw ecn? uint8
| | | | +--rw length? uint16
| | | | +--rw ttl? uint8
| | | | +--rw protocol? uint8
| | | | +--rw ihl? uint8
| | | | +--rw flags? bits
| | | | +--rw offset? uint16
| | | | +--rw identification? uint16
| | | | +--rw (destination-network)?
| | | | | +--:(destination-ipv4-network)
| | | | | +--rw destination-ipv4-network?
| | | | | inet:ipv4-prefix
| | | | +--rw (source-network)?
| | | | | +--:(source-ipv4-network)
| | | | | +--rw source-ipv4-network?
| | | | | inet:ipv4-prefix
| | | | +--rw fragment
| | | | +--rw operator? operator
| | | | +--rw type fragment-type
| | | +--:(ipv6)
| | | ...
| | +--rw (l4)?
| | ...
| +--rw actions
| | ...
| +--ro statistics
| ...
+--ro capabilities
...
Figure 6: DOTS ACLs Subtree (IPv4 Match)
Figure 7 shows the IPv6 match subtree.
module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| ...
| +--rw acls
| +--rw acl* [name]
| ...
| +--rw aces
| +--rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | +--:(ipv4)
| | | | ...
| | | +--:(ipv6)
| | | +--rw ipv6
| | | +--rw dscp? inet:dscp
| | | +--rw ecn? uint8
| | | +--rw length? uint16
| | | +--rw ttl? uint8
| | | +--rw protocol? uint8
| | | +--rw (destination-network)?
| | | | +--:(destination-ipv6-network)
| | | | +--rw destination-ipv6-network?
| | | | inet:ipv6-prefix
| | | +--rw (source-network)?
| | | | +--:(source-ipv6-network)
| | | | +--rw source-ipv6-network?
| | | | inet:ipv6-prefix
| | | +--rw flow-label?
| | | | inet:ipv6-flow-label
| | | +--rw fragment
| | | +--rw operator? operator
| | | +--rw type fragment-type
| | +--rw (l4)?
| | ...
| +--rw actions
| | ...
| +--ro statistics
| ...
+--ro capabilities
...
Figure 7: DOTS ACLs Subtree (IPv6 Match)
Figure 8 shows the TCP match subtree. In addition to the fields defined in [RFC8519], this specification defines a new TCP matching field, called 'flags-bitmask', to efficiently handle TCP flags filtering rules. Some examples are provided in Appendix B.
module: ietf-dots-data-channel
+--rw dots-data
+-rw dots-client* [cuid]
| ...
| +-rw acls
| +-rw acl* [name]
| ...
| +-rw aces
| +-rw ace* [name]
| +-rw name string
| +-rw matches
| | +-rw (l3)?
| | | ...
| | +-rw (l4)?
| | +-:(tcp)
| | | +-rw tcp
| | | +--rw sequence-number? uint32
| | | +--rw acknowledgement-number? uint32
| | | +--rw data-offset? uint8
| | | +--rw reserved? uint8
| | | +--rw flags? bits
| | | +--rw window-size? uint16
| | | +--rw urgent-pointer? uint16
| | | +--rw options? binary
| | | +--rw flags-bitmask
| | | | +--rw operator? operator
| | | | +--rw bitmask uint16
| | | +--rw (source-port)?
| | | | +--:(source-port-range-or-operator)
| | | | +--rw source-port-range-or-operator
| | | | +--rw (port-range-or-operator)?
| | | | +--:(range)
| | | | | +--rw lower-port
| | | | | | inet:port-number
| | | | | +--rw upper-port
| | | | | inet:port-number
| | | | +--:(operator)
| | | | +--rw operator?
| | | | | operator
| | | | +--rw port
| | | | inet:port-number
| | | +--rw (destination-port)?
| | | +--:(destination-port-range-or-operator)
| | | +--rw destination-port-range-or-operator
| | | +--rw (port-range-or-operator)?
| | | +--:(range)
| | | | +--rw lower-port
| | | | | inet:port-number
| | | | +--rw upper-port
| | | | inet:port-number
| | | +--:(operator)
| | | +--rw operator?
| | | | operator
| | | +--rw port
| | | inet:port-number
| | +-:(udp)
| | | ...
| | +-:(icmp)
| | ...
| +-rw actions
| | ...
| +-ro statistics
| ...
+-ro capabilities
...
Figure 8: DOTS ACLs Subtree (TCP Match)
Figure 9 shows the UDP and ICMP match subtrees. The same structure is used for both ICMP and ICMPv6. The indication whether an ACL is about ICMP or ICMPv6 is governed by the 'l3' match or the ACL type.
module: ietf-dots-data-channel
+-rw dots-data
+-rw dots-client* [cuid]
| ...
| +-rw acls
| +-rw acl* [name]
| ...
| +-rw aces
| +-rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | ...
| | +--rw (l4)?
| | +--:(tcp)
| | | ...
| | +--:(udp)
| | | +--rw udp
| | | +--rw length? uint16
| | | +--rw (source-port)?
| | | | +--:(source-port-range-or-operator)
| | | | +--rw source-port-range-or-operator
| | | | +--rw (port-range-or-operator)?
| | | | +--:(range)
| | | | | +--rw lower-port
| | | | | | inet:port-number
| | | | | +--rw upper-port
| | | | | inet:port-number
| | | | +--:(operator)
| | | | +--rw operator?
| | | | | operator
| | | | +--rw port
| | | | inet:port-number
| | | +--rw (destination-port)?
| | | +--:(destination-port-range-or-operator)
| | | +--rw destination-port-range-or-operator
| | | +--rw (port-range-or-operator)?
| | | +--:(range)
| | | | +--rw lower-port
| | | | | inet:port-number
| | | | +--rw upper-port
| | | | inet:port-number
| | | +--:(operator)
| | | +--rw operator?
| | | | operator
| | | +--rw port
| | | inet:port-number
| | +--:(icmp)
| | +--rw icmp
| | +--rw type? uint8
| | +--rw code? uint8
| | +--rw rest-of-header? binary
| +--rw actions
| | ...
| +--ro statistics
| ...
+-ro capabilities
...
Figure 9: DOTS ACLs Subtree (UDP and ICMP Match)
DOTS implementations MUST support the following matching criteria:
The following match fields MUST be supported by DOTS implementations (Table 1):
| ACL Match | Mandatory Fields |
|---|---|
| ipv4 | length, protocol, destination-ipv4-network, source-ipv4-network, and fragment |
| ipv6 | length, protocol, destination-ipv6-network, source-ipv6-network, and fragment |
| tcp | flags-bitmask, source-port-range-or-operator, and destination-port-range-or-operator |
| udp | length, source-port-range-or-operator, and destination-port-range-or-operator |
| icmp | type and code |
Implementations MAY support other filtering match fields and actions. The 'ietf-dots-data-channel' provides a method for an implementation to expose its filtering capabilities. The tree structure of the 'capabilities' is shown in Figure 10. DOTS clients that support both 'fragment' and 'flags' (or 'flags-bitmask' and 'flags') matching fields MUST NOT set these fields in the same request.
module: ietf-dots-data-channel
+--rw dots-data
...
+--ro capabilities
+--ro address-family* enumeration
+--ro forwarding-actions* identityref
+--ro rate-limit? boolean
+--ro transport-protocols* uint8
+--ro ipv4
| +--ro dscp? boolean
| +--ro ecn? boolean
| +--ro length? boolean
| +--ro ttl? boolean
| +--ro protocol? boolean
| +--ro ihl? boolean
| +--ro flags? boolean
| +--ro offset? boolean
| +--ro identification? boolean
| +--ro source-prefix? boolean
| +--ro destination-prefix? boolean
| +--ro fragment? boolean
+--ro ipv6
| +--ro dscp? boolean
| +--ro ecn? boolean
| +--ro length? boolean
| +--ro hoplimit? boolean
| +--ro protocol? boolean
| +--ro destination-prefix? boolean
| +--ro source-prefix? boolean
| +--ro flow-label? boolean
| +--ro fragment? boolean
+--ro tcp
| +--ro sequence-number? boolean
| +--ro acknowledgement-number? boolean
| +--ro data-offset? boolean
| +--ro reserved? boolean
| +--ro flags? boolean
| +--ro window-size? boolean
| +--ro urgent-pointer? boolean
| +--ro options? boolean
| +--ro flags-bitmask? boolean
| +--ro source-port? boolean
| +--ro destination-port? boolean
| +--ro port-range? boolean
+--ro udp
| +--ro length? boolean
| +--ro source-port? boolean
| +--ro destination-port? boolean
| +--ro port-range? boolean
+--ro icmp
+--ro type? boolean
+--ro code? boolean
+--ro rest-of-header? boolean
Figure 10: Filtering Capabilities Subtree
<CODE BEGINS> file "ietf-dots-data-channel@2019-05-09.yang"
module ietf-dots-data-channel {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-data-channel";
prefix data-channel;
import ietf-inet-types {
prefix inet;
reference "Section 4 of RFC 6991";
}
import ietf-access-control-list {
prefix ietf-acl;
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
import ietf-packet-fields {
prefix packet-fields;
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
organization
"IETF DDoS Open Threat Signaling (DOTS) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/dots/>
WG List: <mailto:dots@ietf.org>
Editor: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Editor: Konda, Tirumaleswar Reddy
<mailto:TirumaleswarReddy_Konda@McAfee.com>
Author: Jon Shallow
<mailto:jon.shallow@nccgroup.com>
Author: Kaname Nishizuka
<mailto:kaname@nttv6.jp>
Author: Liang Xia
<mailto:frank.xialiang@huawei.com>
Author: Prashanth Patil
<mailto:praspati@cisco.com>
Author: Andrew Mortensen
<mailto:amortensen@arbor.net>
Author: Nik Teague
<mailto:nteague@verisign.com>";
description
"This module contains YANG definition for configuring
aliases for resources and filtering rules using DOTS
data channel.
Copyright (c) 2019 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
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2019-05-09 {
description
"Initial revision.";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Data Channel Specification";
}
typedef activation-type {
type enumeration {
enum "activate-when-mitigating" {
value 1;
description
"The Access Control List (ACL) is installed only when
a mitigation is active for the DOTS client.";
}
enum "immediate" {
value 2;
description
"The ACL is immediately activated.";
}
enum "deactivate" {
value 3;
description
"The ACL is maintained by the DOTS server, but it is
deactivated.";
}
}
description
"Indicates the activation type of an ACL.";
}
typedef operator {
type bits {
bit not {
position 0;
description
"If set, logical negation of operation.";
}
bit match {
position 1;
description
"Match bit. This is a bitwise match operation
defined as '(data & value) == value'.";
}
bit any {
position 3;
description
"Any bit. This is a match on any of the bits in
bitmask. It evaluates to 'true' if any of the bits
in the value mask are set in the data,
i.e., '(data & value) != 0'.";
}
}
description
"Specifies how to apply the defined bitmask.";
}
grouping tcp-flags {
leaf operator {
type operator;
default "match";
description
"Specifies how to interpret the TCP flags.";
}
leaf bitmask {
type uint16;
mandatory true;
description
"The bitmask matches the last 4 bits of byte 12
and byte 13 of the TCP header. For clarity, the 4 bits
of byte 12 corresponding to the TCP data offset field
are not included in any matching.";
}
description
"Operations on TCP flags.";
}
typedef fragment-type {
type bits {
bit df {
position 0;
description
"Don't fragment bit for IPv4.
Must be set to 0 when it appears in an IPv6 filter.";
}
bit isf {
position 1;
description
"Is a fragment.";
}
bit ff {
position 2;
description
"First fragment.";
}
bit lf {
position 3;
description
"Last fragment.";
}
}
description
"Different fragment types to match against.";
}
grouping target {
description
"Specifies the targets of the mitigation request.";
leaf-list target-prefix {
type inet:ip-prefix;
description
"IPv4 or IPv6 prefix identifying the target.";
}
list target-port-range {
key "lower-port";
description
"Port range. When only lower-port is
present, it represents a single port number.";
leaf lower-port {
type inet:port-number;
mandatory true;
description
"Lower port number of the port range.";
}
leaf upper-port {
type inet:port-number;
must '. >= ../lower-port' {
error-message
"The upper port number must be greater than
or equal to the lower-port number.";
}
description
"Upper port number of the port range.";
}
}
leaf-list target-protocol {
type uint8;
description
"Identifies the target protocol number.
Values are taken from the IANA protocol registry:
https://www.iana.org/assignments/protocol-numbers/
protocol-numbers.xhtml
For example, 6 for TCP or 17 for UDP.";
}
leaf-list target-fqdn {
type inet:domain-name;
description
"FQDN identifying the target.";
}
leaf-list target-uri {
type inet:uri;
description
"URI identifying the target.";
}
}
grouping fragment-fields {
leaf operator {
type operator;
default "match";
description
"Specifies how to interpret the fragment type.";
}
leaf type {
type fragment-type;
mandatory true;
description
"Indicates what fragment type to look for.";
}
description
"Operations on fragment types.";
}
grouping aliases {
description
"Top level container for aliases.";
list alias {
key "name";
description
"List of aliases.";
leaf name {
type string;
description
"The name of the alias.";
}
uses target;
leaf pending-lifetime {
type int32;
units "minutes";
config false;
description
"Indicates the pending validity lifetime of the alias
entry.";
}
}
}
grouping ports {
choice source-port {
container source-port-range-or-operator {
uses packet-fields:port-range-or-operator;
description
"Source port definition.";
}
description
"Choice of specifying the source port or referring to
a group of source port numbers.";
}
choice destination-port {
container destination-port-range-or-operator {
uses packet-fields:port-range-or-operator;
description
"Destination port definition.";
}
description
"Choice of specifying a destination port or referring
to a group of destination port numbers.";
}
description
"Choice of specifying a source or destination port numbers.";
}
grouping access-lists {
description
"Specifies the ordered set of Access Control Lists.";
list acl {
key "name";
ordered-by user;
description
"An ACL is an ordered list of Access Control Entries (ACE).
Each ACE has a list of match criteria and a list of actions.";
leaf name {
type string {
length "1..64";
}
description
"The name of the access list.";
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
leaf type {
type ietf-acl:acl-type;
description
"Type of access control list. Indicates the primary intended
type of match criteria (e.g., IPv4, IPv6) used in the list
instance.";
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
leaf activation-type {
type activation-type;
default "activate-when-mitigating";
description
"Indicates the activation type of an ACL. An ACL can be
deactivated, installed immediately, or installed when
a mitigation is active.";
}
leaf pending-lifetime {
type int32;
units "minutes";
config false;
description
"Indicates the pending validity lifetime of the ACL
entry.";
}
container aces {
description
"The Access Control Entries container contains
a list of ACEs.";
list ace {
key "name";
ordered-by user;
description
"List of access list entries.";
leaf name {
type string {
length "1..64";
}
description
"A unique name identifying this ACE.";
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
container matches {
description
"The rules in this set determine what fields will be
matched upon before any action is taken on them.
If no matches are defined in a particular container,
then any packet will match that container.
If no matches are specified at all in an ACE, then any
packet will match the ACE.";
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
choice l3 {
container ipv4 {
when "derived-from(../../../../type, "
+ "'ietf-acl:ipv4-acl-type')";
uses packet-fields:acl-ip-header-fields;
uses packet-fields:acl-ipv4-header-fields;
container fragment {
description
"Indicates how to handle IPv4 fragments.";
uses fragment-fields;
}
description
"Rule set that matches IPv4 header.";
}
container ipv6 {
when "derived-from(../../../../type, "
+ "'ietf-acl:ipv6-acl-type')";
uses packet-fields:acl-ip-header-fields;
uses packet-fields:acl-ipv6-header-fields;
container fragment {
description
"Indicates how to handle IPv6 fragments.";
uses fragment-fields;
}
description
"Rule set that matches IPv6 header.";
}
description
"Either IPv4 or IPv6.";
}
choice l4 {
container tcp {
uses packet-fields:acl-tcp-header-fields;
container flags-bitmask {
description
"Indicates how to handle TCP flags.";
uses tcp-flags;
}
uses ports;
description
"Rule set that matches TCP header.";
}
container udp {
uses packet-fields:acl-udp-header-fields;
uses ports;
description
"Rule set that matches UDP header.";
}
container icmp {
uses packet-fields:acl-icmp-header-fields;
description
"Rule set that matches ICMP/ICMPv6 header.";
}
description
"Can be TCP, UDP, or ICMP/ICMPv6";
}
}
container actions {
description
"Definitions of action for this ACE.";
leaf forwarding {
type identityref {
base ietf-acl:forwarding-action;
}
mandatory true;
description
"Specifies the forwarding action per ACE.";
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
leaf rate-limit {
when "../forwarding = 'ietf-acl:accept'" {
description
"Rate-limit is valid only when accept action is
used.";
}
type decimal64 {
fraction-digits 2;
}
units "bytes per second";
description
"Specifies how to rate-limit the traffic.";
}
}
container statistics {
config false;
description
"Aggregate statistics.";
uses ietf-acl:acl-counters;
}
}
}
}
}
container dots-data {
description
"Main container for DOTS data channel.";
list dots-client {
key "cuid";
description
"List of DOTS clients.";
leaf cuid {
type string;
description
"A unique identifier that is generated by a DOTS client
to prevent request collisions.";
reference
"RFC YYYY: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification";
}
leaf cdid {
type string;
description
"A client domain identifier conveyed by a
server-domain DOTS gateway to a remote DOTS server.";
reference
"RFC YYYY: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification";
}
container aliases {
description
"Set of aliases that are bound to a DOTS client.";
uses aliases;
}
container acls {
description
"Access lists that are bound to a DOTS client.";
uses access-lists;
}
}
container capabilities {
config false;
description
"Match capabilities";
leaf-list address-family {
type enumeration {
enum "ipv4" {
description
"IPv4 is supported.";
}
enum "ipv6" {
description
"IPv6 is supported.";
}
}
description
"Indicates the IP address families supported by
the DOTS server.";
}
leaf-list forwarding-actions {
type identityref {
base ietf-acl:forwarding-action;
}
description
"Supported forwarding action(s).";
}
leaf rate-limit {
type boolean;
description
"Support of rate-limit action.";
}
leaf-list transport-protocols {
type uint8;
description
"Upper-layer protocol associated with a filtering rule.
Values are taken from the IANA protocol registry:
https://www.iana.org/assignments/protocol-numbers/
protocol-numbers.xhtml
For example, this field contains 1 for ICMP, 6 for TCP
17 for UDP, or 58 for ICMPv6.";
}
container ipv4 {
description
"Indicates IPv4 header fields that are supported to enforce
ACLs.";
leaf dscp {
type boolean;
description
"Support of filtering based on Differentiated Services Code
Point (DSCP).";
}
leaf ecn {
type boolean;
description
"Support of filtering based on Explicit Congestion
Notification (ECN).";
}
leaf length {
type boolean;
description
"Support of filtering based on the Total Length.";
}
leaf ttl {
type boolean;
description
"Support of filtering based on the Time to Live (TTL).";
}
leaf protocol {
type boolean;
description
"Support of filtering based on protocol field.";
}
leaf ihl {
type boolean;
description
"Support of filtering based on the Internet Header
Length (IHL).";
}
leaf flags {
type boolean;
description
"Support of filtering based on the 'flags'.";
}
leaf offset {
type boolean;
description
"Support of filtering based on the 'offset'.";
}
leaf identification {
type boolean;
description
"Support of filtering based on the 'identification'.";
}
leaf source-prefix {
type boolean;
description
"Support of filtering based on the source prefix.";
}
leaf destination-prefix {
type boolean;
description
"Support of filtering based on the destination prefix.";
}
leaf fragment {
type boolean;
description
"Indicates the capability of a DOTS server to
enforce filters on IPv4 fragments. That is, the match
functionality based on the Layer 3 'fragment' clause
is supported.";
}
}
container ipv6 {
description
"Indicates IPv6 header fields that are supported to enforce
ACLs.";
leaf dscp {
type boolean;
description
"Support of filtering based on DSCP.";
}
leaf ecn {
type boolean;
description
"Support of filtering based on ECN.";
}
leaf length {
type boolean;
description
"Support of filtering based on the Payload Length.";
}
leaf hoplimit {
type boolean;
description
"Support of filtering based on the Hop Limit.";
}
leaf protocol {
type boolean;
description
"Support of filtering based on the Next Header field.";
}
leaf destination-prefix {
type boolean;
description
"Support of filtering based on the destination prefix.";
}
leaf source-prefix {
type boolean;
description
"Support of filtering based on the source prefix.";
}
leaf flow-label {
type boolean;
description
"Support of filtering based on the Flow label.";
}
leaf fragment {
type boolean;
description
"Indicates the capability of a DOTS server to
enforce filters on IPv6 fragments.";
}
}
container tcp {
description
"Set of TCP fields that are supported by the DOTS server
to enforce filters.";
leaf sequence-number {
type boolean;
description
"Support of filtering based on the TCP sequence number.";
}
leaf acknowledgement-number {
type boolean;
description
"Support of filtering based on the TCP acknowledgement
number.";
}
leaf data-offset {
type boolean;
description
"Support of filtering based on the TCP data-offset.";
}
leaf reserved {
type boolean;
description
"Support of filtering based on the TCP reserved field.";
}
leaf flags {
type boolean;
description
"Support of filtering, as defined in RFC 8519, based
on the TCP flags.";
}
leaf window-size {
type boolean;
description
"Support of filtering based on the TCP window size.";
}
leaf urgent-pointer {
type boolean;
description
"Support of filtering based on the TCP urgent pointer.";
}
leaf options {
type boolean;
description
"Support of filtering based on the TCP options.";
}
leaf flags-bitmask {
type boolean;
description
"Support of filtering based on the TCP flags bitmask.";
}
leaf source-port {
type boolean;
description
"Support of filtering based on the source port number.";
}
leaf destination-port {
type boolean;
description
"Support of filtering based on the destination port
number.";
}
leaf port-range {
type boolean;
description
"Support of filtering based on a port range.
This includes filtering based on a source port range,
destination port range, or both. All operators
(i.e, less than or equal to, greater than or equal to,
equal to, and not equal to) are supported.";
}
}
container udp {
description
"Set of UDP fields that are supported by the DOTS server
to enforce filters.";
leaf length {
type boolean;
description
"Support of filtering based on the UDP length.";
}
leaf source-port {
type boolean;
description
"Support of filtering based on the source port number.";
}
leaf destination-port {
type boolean;
description
"Support of filtering based on the destination port
number.";
}
leaf port-range {
type boolean;
description
"Support of filtering based on a port range.
This includes filtering based on a source port range,
destination port range, or both. All operators
(i.e, less than or equal, greater than or equal, equal to,
and not equal to) are supported.";
}
}
container icmp {
description
"Set of ICMP/ICMPv6 fields that are supported by the DOTS
server to enforce filters.";
leaf type {
type boolean;
description
"Support of filtering based on the ICMP/ICMPv6 type.";
}
leaf code {
type boolean;
description
"Support of filtering based on the ICMP/ICMPv6 code.";
}
leaf rest-of-header {
type boolean;
description
"Support of filtering based on the ICMP four-bytes
field / the ICMPv6 message body.";
}
}
}
}
}
<CODE ENDS>
This module uses the common YANG types defined in [RFC6991] and types defined in [RFC8519].
In order to make use of DOTS data channel, a DOTS client MUST register to its DOTS server(s) by creating a DOTS client ('dots-client') resource. To that aim, DOTS clients SHOULD send a POST request (shown in Figure 11).
POST /restconf/data/ietf-dots-data-channel:dots-data HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "string"
}
]
}
Figure 11: POST to Register Schema
The 'cuid' (client unique identifier) parameter is described below:
POST /restconf/data/ietf-dots-data-channel:dots-data HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "string",
"cdid": "string"
}
]
}
Figure 12: POST to Register Schema (via a Server-Domain DOTS Gateway)
In deployments where server-domain DOTS gateways are enabled, identity information about the origin source client domain SHOULD be supplied to the DOTS server. That information is meant to assist the DOTS server to enforce some policies. These policies can be enforced per-client, per-client domain, or both. Figure 12 shows a schema example of a request relayed by a server-domain DOTS gateway.
A request example to create a 'dots-client' resource is depicted in Figure 13. This request is relayed by a server-domain DOTS gateway as hinted by the presence of the 'cdid' attribute.
POST /restconf/data/ietf-dots-data-channel:dots-data HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "dz6pHjaADkaFTbjr0JGBpw",
"cdid": "7eeaf349529eb55ed50113"
}
]
}
Figure 13: POST to Register (DOTS gateway)
As a reminder, DOTS gateways may rewrite the 'cuid' used by peer DOTS clients (Section 4.4.1 of [I-D.ietf-dots-signal-channel]).
DOTS servers can identify the DOTS client domain using the 'cdid' parameter or using the client's DNS name specified in the Subject Alternative Name extension's dNSName type in the client certificate [RFC6125].
DOTS servers MUST limit the number of 'dots-client' resources to be created by the same DOTS client to 1 per request. Requests with multiple 'dots-client' resources MUST be rejected by DOTS servers. To that aim, the DOTS server MUST rely on the same procedure to unambiguously identify a DOTS client as discussed in Section 4.4.1 of [I-D.ietf-dots-signal-channel].
The DOTS server indicates the result of processing the POST request using status-line codes. Status codes in the range "2xx" codes are success, "4xx" codes are some sort of invalid requests and "5xx" codes are returned if the DOTS server has erred or is incapable of accepting the creation of the 'dots-client' resource. In particular,
Once a DOTS client registers itself to a DOTS server, it can create/delete/retrieve aliases (Section 6) and filtering rules (Section 7).
A DOTS client MAY use the PUT request (Section 4.5 in [RFC8040]) to register a DOTS client within the DOTS server. An example is shown in Figure 14.
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "dz6pHjaADkaFTbjr0JGBpw"
}
]
}
Figure 14: PUT to Register
The DOTS gateway that inserted a 'cdid' in a PUT request MUST strip the 'cdid' parameter in the corresponding response before forwarding the response to the DOTS client.
A DOTS client de-registers from its DOTS server(s) by deleting the 'cuid' resource(s). Resources bound to this DOTS client will be deleted by the DOTS server. An example of a de-register request is shown in Figure 15.
DELETE /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: example.com
Figure 15: De-register a DOTS Client
The following sub-sections define means for a DOTS client to create aliases (Section 6.1), retrieve one or a list of aliases (Section 6.2), and delete an alias (Section 6.3).
A POST or PUT request is used by a DOTS client to create aliases, for resources for which a mitigation may be requested. Such aliases may be used in subsequent DOTS signal channel exchanges to refer more efficiently to the resources under attack.
DOTS clients within the same domain can create different aliases for the same resource.
The structure of POST requests used to create aliases is shown in Figure 16.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=cuid HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:aliases": {
"alias": [
{
"name": "string",
"target-prefix": [
"string"
],
"target-port-range": [
{
"lower-port": integer,
"upper-port": integer
}
],
"target-protocol": [
integer
],
"target-fqdn": [
"string"
],
"target-uri": [
"string"
]
}
]
}
}
Figure 16: POST to Create Aliases (Request Schema)
The parameters are described below:
In POST or PUT requests, at least one of the 'target-prefix', 'target-fqdn', or 'target-uri' attributes MUST be present. DOTS agents can safely ignore Vendor-Specific parameters they don't understand.
If more than one 'target-*' scope types (e.g., 'target-prefix' and 'target-fqdn' or 'target-fqdn' and 'target-uri') are included in a POST or PUT request, the DOTS server binds all resulting IP addresses/prefixes to the same resource.
Figure 17 shows a POST request to create an alias called "https1" for HTTPS servers with IP addresses 2001:db8:6401::1 and 2001:db8:6401::2 listening on TCP port number 443.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: www.example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:aliases": {
"alias": [
{
"name": "https1",
"target-protocol": [
6
],
"target-prefix": [
"2001:db8:6401::1/128",
"2001:db8:6401::2/128"
],
"target-port-range": [
{
"lower-port": 443
}
]
}
]
}
}
Figure 17: Example of a POST to Create an Alias
"201 Created" status-line MUST be returned in the response if the DOTS server has accepted the alias.
"409 Conflict" status-line MUST be returned to the requesting DOTS client, if the request is conflicting with an existing alias name. The error-tag "resource-denied" is used in this case.
If the request is missing a mandatory attribute or it contains an invalid or unknown parameter, "400 Bad Request" status-line MUST be returned by the DOTS server. The error-tag is set to "missing-attribute", "invalid-value", or "unknown-element" as a function of the encountered error.
If the request is received via a server-domain DOTS gateway, but the DOTS server does not maintain a 'cdid' for this 'cuid' while a 'cdid' is expected to be supplied, the DOTS server MUST reply with "403 Forbidden" status-line and the error-tag "access-denied". Upon receipt of this message, the DOTS client MUST register (Section 5).
A DOTS client uses the PUT request to modify the aliases in the DOTS server. In particular, a DOTS client MUST update its alias entries upon change of the prefix indicated in the 'target-prefix'.
A DOTS server MUST maintain an alias for at least 10080 minutes (1 week). If no refresh request is seen from the DOTS client, the DOTS server removes expired entries.
A GET request is used to retrieve one or all installed aliases by a DOTS client from a DOTS server (Section 3.3.1 in [RFC8040]). If no 'name' is included in the request, this is an indication that the request is about retrieving all aliases instantiated by the DOTS client.
Figure 18 shows an example to retrieve all the aliases that were instantiated by the requesting DOTS client. The "content" query parameter and its permitted values are defined in Section 4.8.1 of [RFC8040].
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/aliases?content=all HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Figure 18: GET to Retrieve All Installed Aliases
Figure 19 shows an example of the response message body that includes all the aliases that are maintained by the DOTS server for the DOTS client identified by the 'cuid' parameter.
{
"ietf-dots-data-channel:aliases": {
"alias": [
{
"name": "Server1",
"target-protocol": [
6
],
"target-prefix": [
"2001:db8:6401::1/128",
"2001:db8:6401::2/128"
],
"target-port-range": [
{
"lower-port": 443
}
],
"pending-lifetime": 3596
},
{
"name": "Server2",
"target-protocol": [
6
],
"target-prefix": [
"2001:db8:6401::10/128",
"2001:db8:6401::20/128"
],
"target-port-range": [
{
"lower-port": 80
}
],
"pending-lifetime": 9869
}
]
}
}
Figure 19: An Example of Response Body Listing All Installed Aliases
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/aliases/alias=Server2?content=all HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Figure 20: GET to Retrieve an Alias
Figure 20 shows an example of a GET request to retrieve the alias "Server2" that was instantiated by the DOTS client.
If an alias name ('name') is included in the request, but the DOTS server does not find that alias name for this DOTS client in its configuration data, it MUST respond with a "404 Not Found" status-line.
A DELETE request is used to delete an alias maintained by a DOTS server.
If the DOTS server does not find the alias name, conveyed in the DELETE request, in its configuration data for this DOTS client, it MUST respond with a "404 Not Found" status-line.
The DOTS server successfully acknowledges a DOTS client's request to remove the alias using "204 No Content" status-line in the response.
Figure 21 shows an example of a request to delete an alias.
DELETE /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/aliases/alias=Server1 HTTP/1.1
Host: example.com
Figure 21: Delete an Alias
The following sub-sections define means for a DOTS client to retrieve DOTS filtering capabilities (Section 7.1), create filtering rules (Section 7.2), retrieve active filtering rules (Section 7.3), and delete a filtering rule (Section 7.4).
A DOTS client MAY send a GET request to retrieve the filtering capabilities supported by a DOTS server. Figure 22 shows an example of such request.
GET /restconf/data/ietf-dots-data-channel:dots-data\
/capabilities HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Figure 22: GET to Retrieve the Capabilities of a DOTS Server
A DOTS client which issued a GET request to retrieve the filtering capabilities supported by its DOTS server, SHOULD NOT request for filtering actions that are not supported by that DOTS server.
Figure 23 shows an example of a response body received from a DOTS server which supports:
{
"ietf-dots-data-channel:capabilities": {
"address-family": ["ipv4", "ipv6"],
"forwarding-actions": ["drop", "accept"],
"rate-limit": true,
"transport-protocols": [1, 6, 17, 58],
"ipv4": {
"length": true,
"protocol": true,
"destination-prefix": true,
"source-prefix": true,
"fragment": true
},
"ipv6": {
"length": true,
"protocol": true,
"destination-prefix": true,
"source-prefix": true,
"fragment": true
},
"tcp": {
"flags-bitmask": true,
"source-port": true,
"destination-port": true,
"port-range": true
},
"udp": {
"length": true,
"source-port": true,
"destination-port": true,
"port-range": true
},
"icmp": {
"type": true,
"code": true
}
}
}
Figure 23: Reply to a GET Request with Filtering Capabilities (Message Body)
A POST or PUT request is used by a DOTS client to communicate filtering rules to a DOTS server.
Figure 24 shows a POST request example to block traffic from 192.0.2.0/24 and destined to 198.51.100.0/24. Other examples are discussed in Appendix A.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "sample-ipv4-acl",
"type": "ipv4-acl-type",
"activation-type": "activate-when-mitigating",
"aces": {
"ace": [
{
"name": "rule1",
"matches": {
"ipv4": {
"destination-ipv4-network": "198.51.100.0/24",
"source-ipv4-network": "192.0.2.0/24"
}
},
"actions": {
"forwarding": "drop"
}
}
]
}
}
]
}
}
Figure 24: POST to Install Filtering Rules
The meaning of these parameters is as follows:
The DOTS server indicates the result of processing the POST request using the status-line. Concretely, "201 Created" status-line MUST be returned in the response if the DOTS server has accepted the filtering rules. If the request is missing a mandatory attribute or contains an invalid or unknown parameter (e.g., a match field not supported by the DOTS server), "400 Bad Request" status-line MUST be returned by the DOTS server in the response. The error-tag is set to "missing-attribute", "invalid-value", or "unknown-element" as a function of the encountered error.
If the request is received via a server-domain DOTS gateway, but the DOTS server does not maintain a 'cdid' for this 'cuid' while a 'cdid' is expected to be supplied, the DOTS server MUST reply with "403 Forbidden" status-line and the error-tag "access-denied". Upon receipt of this message, the DOTS client MUST register (Figure 11).
If the request is conflicting with an existing filtering installed by another DOTS client of the domain, absent any local policy, the DOTS server returns "409 Conflict" status-line to the requesting DOTS client. The error-tag "resource-denied" is used in this case.
The "insert" query parameter (Section 4.8.5 of [RFC8040]) MAY be used to specify how an access control entry is inserted within an ACL and how an ACL is inserted within an ACL set.
The DOTS client uses the PUT request to modify its filtering rules maintained by the DOTS server. In particular, a DOTS client MUST update its filtering entries upon change of the destination-prefix. How such change is detected is out of scope.
A DOTS server MUST maintain a filtering rule for at least 10080 minutes (1 week). If no refresh request is seen from the DOTS client, the DOTS server removes expired entries. Typically, a refresh request is a PUT request which echoes the content of a response to a GET request with all of the read-only parameters stripped out (e.g., pending-lifetime).
A DOTS client periodically queries its DOTS server to check the counters for installed filtering rules. A GET request is used to retrieve filtering rules from a DOTS server. In order to indicate which type of data is requested in a GET request, the DOTS client sets adequately the "content" query parameter.
If the DOTS server does not find the access list name conveyed in the GET request in its configuration data for this DOTS client, it responds with a "404 Not Found" status-line.
In order to illustrate the intended behavior, consider the example depicted in Figure 25. In reference to this example, the DOTS client requests the creation of an immediate ACL called "test-acl-ipv6-udp".
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=test-acl-ipv6-udp HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"type": "ipv6-acl-type",
"activation-type": "immediate",
"aces": {
"ace": [
{
"name": "my-test-ace",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 25: Example of a PUT Request to Create a Filtering
The peer DOTS server follows the procedure specified in Section 7.2 to process the request. We consider in the following that a positive response is sent back to the requesting DOTS client to confirm that the "test-acl-ipv6-udp" ACL is successfully installed by the DOTS server.
The DOTS client can issue a GET request to retrieve all its filtering rules and the number of matches for the installed filtering rules as illustrated in Figure 26. The "content" query parameter is set to 'all'. The message body of the response to this GET request is shown in Figure 27.
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/acls?content=all HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Figure 26: Retrieve the Configuration Data and State Data for the Filtering Rules (GET Request)
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"type": "ipv6-acl-type",
"activation-type": "immediate",
"pending-lifetime":9080,
"aces": {
"ace": [
{
"name": "my-test-ace",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 27: Retrieve the Configuration Data and State Data for the Filtering Rules (Response Message Body)
Also, a DOTS client can issue a GET request to retrieve only configuration data related to an ACL as shown in Figure 28. It does so by setting the "content" query parameter to 'config'.
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=test-acl-ipv6-udp?content=config HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Figure 28: Retrieve the Configuration Data for a Filtering Rule (GET Request)
A response to this GET request is shown in Figure 29.
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"type": "ipv6-acl-type",
"activation-type": "immediate",
"aces": {
"ace": [
{
"name": "my-test-ace",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 29: Retrieve the Configuration Data for a Filtering Rule (Response Message Body)
A DOTS client can also issue a GET request with a "content" query parameter set to 'non-config' to exclusively retrieve non-configuration data bound to a given ACL as shown in Figure 30. A response to this GET request is shown in Figure 31.
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=test-acl-ipv6-udp?content=non-config HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Figure 30: Retrieve the Non-Configuration Data for a Filtering Rule (GET Request)
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"pending-lifetime": 8000,
"aces": {
"ace": [
{
"name": "my-test-ace"
}
]
}
}
]
}
}
Figure 31: Retrieve the Non-Configuration Data for a Filtering Rule (Response Message Body)
A DELETE request is used by a DOTS client to delete filtering rules from a DOTS server.
If the DOTS server does not find the access list name carried in the DELETE request in its configuration data for this DOTS client, it MUST respond with a "404 Not Found" status-line. The DOTS server successfully acknowledges a DOTS client's request to withdraw the filtering rules using "204 No Content" status-line, and removes the filtering rules accordingly.
Figure 32 shows an example of a request to remove the IPv4 ACL "sample-ipv4-acl" created in Section 7.2.
DELETE /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw/acls\
/acl=sample-ipv4-acl HTTP/1.1
Host: example.com
Figure 32: Remove a Filtering Rule (DELETE Request)
Figure 33 shows an example of a response received from the DOTS server to confirm the deletion of "sample-ipv4-acl".
HTTP/1.1 204 No Content Server: Apache Date: Fri, 27 Jul 2018 10:05:15 GMT Cache-Control: no-cache Content-Type: application/yang-data+json Content-Length: 0 Connection: Keep-Alive
Figure 33: Remove a Filtering Rule (Response)
The following operational considerations should be taken into account:
URI: urn:ietf:params:xml:ns:yang:ietf-dots-data-channel
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
Name: ietf-dots-data-channel
Namespace: urn:ietf:params:xml:ns:yang:ietf-dots-data-channel
Prefix: data-channel
Reference: RFC XXXX
This document requests IANA to register the following URI in the "ns" subregistry within the "IETF XML Registry" [RFC3688]: [RFC7950] within the "YANG Parameters" registry.
This module is not maintained by IANA.
RESTCONF security considerations are discussed in [RFC8040]. In particular, DOTS agents MUST follow the security recommendations in Sections 2 and 12 of [RFC8040]. Also, DOTS agents MUST support the mutual authentication TLS profile discussed in Sections 7.1 and 8 of [I-D.ietf-dots-signal-channel].
Authenticated encryption MUST be used for data confidentiality and message integrity. The interaction between the DOTS agents requires Transport Layer Security (TLS) with a cipher suite offering confidentiality protection and the guidance given in [RFC7525] MUST be followed to avoid attacks on TLS.
The installation of drop- or accept-list rules using RESTCONF over TLS reveals the attacker IP addresses and legitimate IP addresses only to the DOTS server trusted by the DOTS client. The secure communication channel between DOTS agents provides privacy and prevents a network eavesdropper from directly gaining access to the drop- and accept-listed IP addresses.
An attacker may be able to inject RST packets, bogus application segments, etc., regardless of whether TLS authentication is used. Because the application data is TLS protected, this will not result in the application receiving bogus data, but it will constitute a DoS on the connection. This attack can be countered by using TCP-AO [RFC5925]. If TCP-AO is used, then any bogus packets injected by an attacker will be rejected by the TCP-AO integrity check and therefore will never reach the TLS layer.
In order to prevent leaking internal information outside a client-domain, client-side DOTS gateways SHOULD NOT reveal the identity of internal DOTS clients (e.g., source IP address, client's hostname) unless explicitly configured to do so.
DOTS servers MUST verify that requesting DOTS clients are entitled to enforce filtering rules on a given IP prefix. That is, only filtering rules on IP resources that belong to the DOTS client domain can be authorized by a DOTS server. The exact mechanism for the DOTS servers to validate that the target prefixes are within the scope of the DOTS client domain is deployment-specific.
Rate-limiting DOTS requests, including those with new 'cuid' values, from the same DOTS client defends against DoS attacks that would result from varying the 'cuid' to exhaust DOTS server resources. Rate-limit policies SHOULD be enforced on DOTS gateways (if deployed) and DOTS servers.
Applying resources quota per DOTS client and/or per DOTS client domain (e.g., limit the number of aliases and filters to be installed by DOTS clients) prevents DOTS server resources to be aggressively used by some DOTS clients and ensures, therefore, DDoS mitigation usage fairness. Additionally, DOTS servers may limit the number of DOTS clients that can be enabled per domain.
When FQDNs are used as targets, the DOTS server MUST rely upon DNS privacy enabling protocols (e.g., DNS over TLS [RFC7858] or DoH [RFC8484]) to prevent eavesdroppers from possibly identifying the target resources protected by the DDoS mitigation service, and means to ensure the target FQDN resolution is authentic (e.g., DNSSEC [RFC4034]).
The presence of DOTS gateways may lead to infinite forwarding loops, which is undesirable. To prevent and detect such loops, a mechanism is defined in Section 3.4.
All data nodes defined in the YANG module which can be created, modified, and deleted (i.e., config true, which is the default) are considered sensitive. Write operations applied to these data nodes without proper protection can negatively affect network operations. This module reuses YANG structures from [RFC8519], and the security considerations for those nodes continue to apply for this usage. Appropriate security measures are recommended to prevent illegitimate users from invoking DOTS data channel primitives. Nevertheless, an attacker who can access a DOTS client is technically capable of launching various attacks, such as:
The following individuals co-authored this document:
Kaname Nishizuka NTT Communications GranPark 16F 3-4-1 Shibaura, Minato-ku Tokyo 108-8118 Japan Email: kaname@nttv6.jp Liang Xia Huawei 101 Software Avenue, Yuhuatai District Nanjing, Jiangsu 210012 China Email: frank.xialiang@huawei.com Prashanth Patil Cisco Systems, Inc. Email: praspati@cisco.com Andrew Mortensen Arbor Networks, Inc. 2727 S. State St Ann Arbor, MI 48104 United States Email: andrew.mortensen@netscout.com Nik Teague Iron Mountain Data Centers United Kingdom Email: nteague@ironmountain.co.uk
The following individuals have contributed to this document:
Thanks to Christian Jacquenet, Roland Dobbins, Roman Danyliw, Ehud Doron, Russ White, Gilbert Clark, Kathleen Moriarty, Nesredien Suleiman, Roni Even, and Brian Trammel for the discussion and comments.
The authors would like to give special thanks to Kaname Nishizuka and Jon Shallow for their efforts in implementing the protocol and performing interop testing at IETF Hackathons.
Many thanks to Ben Kaduk for the detailed AD review.
Thanks to Martin Bjorklund for the guidance on RESTCONF.
Thanks to Alexey Melnikov, Adam Roach, Suresh Krishnan, Mirja Kühlewind, and Warren Kumari for the review.
This specification strongly recommends the use of "fragment" for handling fragments.
Figure 34 shows the content of the POST request to be issued by a DOTS client to its DOTS server to allow the traffic destined to 198.51.100.0/24 and UDP port number 53, but to drop all fragmented packets. The following ACEs are defined (in this order):
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "dns-fragments",
"type": "ipv4-acl-type",
"aces": {
"ace": [
{
"name": "drop-all-fragments",
"matches": {
"ipv4": {
"fragment": {
"operator": "match",
"type": "isf"
}
}
},
"actions": {
"forwarding": "drop"
}
}
]
"ace": [
{
"name": "allow-dns-packets",
"matches": {
"ipv4": {
"destination-ipv4-network": "198.51.100.0/24"
}
"udp": {
"destination-port": {
"operator": "eq",
"port": 53
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 34: Filtering IPv4 Fragmented Packets
Figure 35 shows a POST request example issued by a DOTS client to its DOTS server to allow the traffic destined to 2001:db8::/32 and UDP port number 53, but to drop all fragmented packets. The following ACEs are defined (in this order):
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "dns-fragments",
"type": "ipv6-acl-type",
"aces": {
"ace": [
{
"name": "drop-all-fragments",
"matches": {
"ipv6": {
"fragment": {
"operator": "match",
"type": "isf"
}
}
},
"actions": {
"forwarding": "drop"
}
}
]
"ace": [
{
"name": "allow-dns-packets",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8::/32"
}
"udp": {
"destination-port": {
"operator": "eq",
"port": 53
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 35: Filtering IPv6 Fragmented Packets
This section provides sample examples to illustrate TCP-specific filtering based on the flag bits. These examples should not be interpreted as recommended filtering behaviors under specific DDoS attacks.
Figure 36 shows an example of a DOTS request sent by a DOTS client to install immediately a filter to discard incoming TCP messages having all flags unset. The bitmask can be set to 255 to check against the (CWR, ECE, URG, ACK, PSH, RST, SYN, FIN) flags.
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=tcp-flags-example HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [{
"name": "tcp-flags-example",
"activation-type": "immediate",
"aces": {
"ace": [{
"name": "null-attack",
"matches": {
"tcp": {
"flags-bitmask": {
"operator": "not any",
"bitmask": 4095
}
}
},
"actions": {
"forwarding": "drop"
}
}]
}
}]
}
}
Figure 36: Example of a DOTS Request to Deny TCP Null Attack Messages
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=tcp-flags-example HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [{
"name": "tcp-flags-example",
"activation-type": "activate-when-mitigating",
"aces": {
"ace": [{
"name": "rate-limit-syn",
"matches": {
"tcp": {
"flags-bitmask": {
"operator": "match",
"bitmask": 2
}
}
},
"actions": {
"forwarding": "accept",
"rate-limit": "20.00"
}
}]
}
}]
}
}
Figure 37: Example of DOTS Request to Rate-Limit Incoming TCP SYNs
Figure 37 shows an ACL example to rate-limit incoming SYNs during a SYN-flood attack.
Figure 38 shows an ACL example to rate-limit incoming ACKs during an ACK-flood attack.
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=tcp-flags-example HTTP/1.1
Host: example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [{
"name": "tcp-flags-example",
"type": "ipv4-acl-type",
"activation-type": "activate-when-mitigating",
"aces": {
"ace": [{
"name": "rate-limit-ack",
"matches": {
"tcp": {
"flags-bitmask": {
"operator": "match",
"bitmask": 16
}
}
},
"actions": {
"forwarding": "accept",
"rate-limit": "20.00"
}
}]
}
}]
}
}
Figure 38: Example of DOTS Request to Rate-Limit Incoming TCP ACKs