| DOTS | T. Reddy |
| Internet-Draft | D. Wing |
| Intended status: Standards Track | Cisco |
| Expires: April 30, 2017 | M. Boucadair |
| Orange | |
| K. Nishizuka | |
| NTT Communications | |
| L. Xia | |
| Huawei | |
| October 27, 2016 |
Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel
draft-reddy-dots-data-channel-01
The document specifies a Distributed Denial-of-Service Open Threat Signaling (DOTS) data channel used for bulk exchange of data not easily or appropriately communicated through the DOTS signal channel under attack conditions. This is a companion document to the DOTS signal channel specification.
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 http://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 April 30, 2017.
Copyright (c) 2016 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 (http://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 in this attack can be an application server, a client, a router, a firewall, or an entire network.
+---------------+ +---------------+
| | <------- Signal Channel ------> | |
| DOTS Client | | DOTS Server |
| | <======= Data Channel ======> | |
+---------------+ +---------------+
Figure 1: DOTS Channels
DDoS Open Threat Signaling (DOTS) defines two channels: signal and data channels [I-D.ietf-dots-architecture] (Figure 1). The DOTS signal channel used to convey that a network is under a DDOS attack to an upstream DOTS server so that appropriate mitigation actions are undertaken on the suspect traffic is further elaborated in [I-D.reddy-dots-signal-channel]. The DOTS data channel is used for infrequent bulk data exchange between DOTS agents in the aim to significantly augment attack response coordination.
Section 2 of [I-D.ietf-dots-architecture] identifies that the DOTS data channel is used to perform the tasks listed below:
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 [RFC2119].
The reader should be familiar with the terms defined in [I-D.ietf-dots-architecture].
The DOTS data channel is intended to be used for bulk data exchanges between DOTS agents. Unlike the signal channel, which must operate nominally even when confronted with despite signal degradation due to packet loss, the data channel is not expected to be constructed to deal with attack conditions.
As the primary function of the data channel is data exchange, a reliable transport is required in order for DOTS agents to detect data delivery success or failure. Constrained Application Protocol (CoAP) [RFC7252] over TLS [RFC5246] over TCP is used for DOTS data channel (Figure 2). COAP was designed according to the REST architecture, and thus exhibits functionality similar to that of HTTP, it is quite straightforward to map from CoAP to HTTP and from HTTP to CoAP.
+--------------+
| DOTS |
+--------------+
| CoAP |
+--------------+
| TLS |
+--------------+
| TCP |
+--------------+
| IP |
+--------------+
Figure 2: Abstract Layering of DOTS data channel over CoAP over TLS
JSON [RFC7159] payloads is used to convey DOTS signal channel session configuration, filtering rules as well as data channel specific payload messages that convey request parameters and response information such as errors. All data channel URIs defined in this document, and in subsequent documents, MUST NOT have a URI containing "/DOTS-signal".
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 client SHOULD re-use the TLS session.
A DOTS client registers itself to its DOTS server(s) in order to set up DOTS related configuration and policy information exchange between the two DOTS agents.
A POST request is used to create identifiers, such as names or aliases, for resources for which a mitigation may be requested. Such identifiers may then be used in subsequent DOTS signal channel exchanges to refer more efficiently to the resources under attack (Figure 3).
Header: POST (Code=0.02)
Uri-Host: "host"
Uri-Path: ".well-known"
Uri-Path: "version"
Uri-Path: "DOTS-data-channel"
Uri-Path: "identifier"
Content-Format: "application/json"
{
"policy-id": "integer",
"id": { "alias-name" : [
"traffic-protocol": "string",
"destination-protocol-port": "string",
"destination-ip": "string",
],
"alias-name" : [
"FQDN": "string",
],
"alias-name" : [
"URI": "string",
],
}
"alias-name" : [
"E.164": "string",
]
}
}
Figure 3: POST to create identifiers
The header fields are described below:
In the POST request at least one of the attributes traffic-protocol or destination-protocol-port or destination-ip or FQDN or URI or E.164 MUST be present.
Figure 4 shows a POST request to create alias called "https1" for HTTPS servers with IP addresses 2002:db8:6401::1 and 2002:db8:6401::2 listening on port 443.
Header: POST (Code=0.02)
Uri-Host: "www.example.com"
Uri-Path: ".well-known"
Uri-Path: "v1"
Uri-Path: "DOTS-data-channel"
Uri-Path: "identifier"
Content-Format: "application/json"
{
"policy-id": 123321333242,
"id": { "Server1" : [
"traffic-protocol": "tcp",
"destination-protocol-port": "443",
"destination-ip": "2002:db8:6401::1,
2002:db8:6401::2",
]
}
}
Figure 4: POST to create identifiers
The DOTS server indicates the result of processing the POST request using CoAP response codes. CoAP 2.xx codes are success, CoAP 4.xx codes are some sort of invalid requests and 5.xx codes are returned if the DOTS server has erred or it is incapable of accepting the alias. Response code 2.01 (Created) will be returned in the response if the DOTS server has accepted the alias. If the request is missing one or more mandatory attributes, then 4.00 (Bad Request) will be returned in the response or if the request contains invalid or unknown parameters then 4.02 (Invalid query) will be returned in the response. The CoAP response will include the JSON body received in the request.
A DELETE request is used to delete an identifier maintained by a DOTS server (Figure 5).
Header: DELETE (Code=0.04)
Uri-Host: "host"
Uri-Path: ".well-known"
Uri-Path: "version"
Uri-Path: "DOTS-data-channel"
Uri-Path: "identifier"
Content-Format: "application/json"
{
"policy-id": "number"
}
Figure 5: DELETE identifier
If the DOTS server does not find the policy number conveyed in the DELETE request in its policy state data, then it responds with a 4.04 (Not Found) error response code. The DOTS server successfully acknowledges a DOTS client's request to remove the identifier using 2.02 (Deleted) response code.
A GET request is used to retrieve the set of installed identifiers from a DOTS server.
Figure 6 shows how to retrieve all the identifiers that were instantiated by the DOTS client while Figure 7 shows how to retrieve a specific identifier.
Header: GET (Code=0.01) Uri-Host: "host" Uri-Path: ".well-known" Uri-Path: "version" Uri-Path: "DOTS-data-channel" Uri-Path: "identifier"
Figure 6: GET to retrieve all the installed identifiers
Header: GET (Code=0.01) Uri-Host: "host" Uri-Path: ".well-known" Uri-Path: "version" Uri-Path: "DOTS-data-channel" Uri-Path: "identifier" Uri-Path: "policy-id value"
Figure 7: GET to retrieve the specific identifier
Figure 8 shows response for all identifiers on the DOTS server.
{
"policy-data":[
{
"policy-id": 1234534333242
"id": { "Server1" : [
"traffic-protocol": "tcp",
"destination-protocol-port": "443",
"destination-ip": "2002:db8:6401::1,
2002:db8:6401::2",
]
}
},
{
"policy-id": 1233213344443
"id": { "Server2" : [
"traffic-protocol": "tcp",
"destination-protocol-port": "80",
"destination-ip": "2002:db8:6401::10,
2002:db8:6401::20",
]
}
}
]
}
Figure 8: Response body
If the DOTS server does not find the policy number conveyed in the GET request in its policy state data, then it responds with a 4.04 (Not Found) error response code.
One of the possible arrangements for a DOTS client to signal filtering rules to a DOTS server via the DOTS gateway is discussed below:
The DOTS data channel conveys the filtering rules to the DOTS gateway. The DOTS gateway validates if the DOTS client is authorized to signal the filtering rules and if the client is authorized propagates the rules to the DOTS server. Likewise, the DOTS server validates if the DOTS gateway is authorized to signal the filtering rules. To create or purge filters, the DOTS client sends CoAP requests to the DOTS gateway. The DOTS gateway validates the rules and proxies the requests containing the filtering rules to a DOTS server. When the DOTS gateway receives the associated CoAP response from the DOTS server, it propagates the response back to the DOTS client.
The following APIs define means for a DOTS client to configure filtering rules on a DOTS server.
A POST request is used to push filtering rules to a DOTS server (Figure 9).
Header: POST (Code=0.02)
Uri-Host: "host"
Uri-Path: ".well-known"
Uri-Path: "version"
Uri-Path: "DOTS-data-channel"
Uri-Path: "filter"
Content-Format: "application/json"
{
"policy-id": "integer",
"traffic-protocol": "string",
"source-protocol-port": "string",
"destination-protocol-port": "string",
"destination-ip": "string",
"source-ip": "string",
"lifetime": "number",
"dscp": "string",
"traffic-rate" : "number"
}
Figure 9: POST to install filtering rules
The header fields are described below:
In the POST request at least one of the attributes traffic-protocol or source-protocol-port or destination-protocol-port or destination-ip or source-ip MUST be present. The relative order of two rules is determined by comparing their respective policy identifiers. The rule with higher numeric policy identifier value has higher precedence (and thus will match before) than the rule with lower numeric policy identifier value.
Figure 10 shows a POST request to block traffic from an attacker using 2001:db8:abcd:3f01::/64 IPv6 prefix to a network resource reachable at IP address 2002:db8:6401::1 to operate a server on TCP port 443.
Header: POST (Code=0.02)
Uri-Host: "www.example.com"
Uri-Path: ".well-known"
Uri-Path: "v1"
Uri-Path: "DOTS-data-channel"
Content-Format: "application/json"
{
"policy-id": 123321333242,
"traffic-protocol": "tcp",
"source-protocol-port": "0-65535",
"destination-protocol-port": "443",
"destination-ip": "2001:db8:abcd:3f01::/64",
"source-ip": "2002:db8:6401::1",
"lifetime": 1800,
"traffic-rate": 0
}
Figure 10: POST to Install filterng rules
The DOTS server indicates the result of processing the POST request using CoAP response codes. CoAP 2.xx codes are success, CoAP 4.xx codes are some sort of invalid request and 5.xx codes are returned if the DOTS server has erred or is incapable of configuring the filtering rules. Response code 2.01 (Created) will be returned in the response if the DOTS server has accepted the filtering rules. If the request is missing one or more mandatory attributes then 4.00 (Bad Request) will be returned in the response or if the request contains invalid or unknown parameters then 4.02 (Invalid query) will be returned in the response. The CoAP response will include the JSON body received in the request.
A DELETE request is used to delete filtering rules from a DOTS server (Figure 11).
Header: DELETE (Code=0.04)
Uri-Host: "host"
Uri-Path: ".well-known"
Uri-Path: "version"
Uri-Path: "DOTS-data-channel"
Content-Format: "application/json"
{
"policy-id": "number"
}
Figure 11: DELETE to remove the filtering rules
If the DOTS server does not find the policy number conveyed in the DELETE request in its policy state data, then it responds with a 4.04 (Not Found) error response code. The DOTS server successfully acknowledges a DOTS client's request to withdraw the filtering rules using 2.02 (Deleted) response code, and removes the filtering rules as soon as possible.
The DOTS client periodically queries the DOTS server to check the counters for installed filtering rules. A GET request is used to retrieve filtering rules from a DOTS server.
Figure 12 shows how to retrieve all the filtering rules programmed by the DOTS client while Figure 13 shows how to retrieve specific filtering rules programmed by the DOTS client.
Header: GET (Code=0.01) Uri-Host: "host" Uri-Path: ".well-known" Uri-Path: "version" Uri-Path: "DOTS-data-channel" Uri-Path: "list"
Figure 12: GET to retrieve the filtering rules (1)
Header: GET (Code=0.01) Uri-Host: "host" Uri-Path: ".well-known" Uri-Path: "version" Uri-Path: "DOTS-data-channel" Uri-Path: "policy-id value"
Figure 13: GET to retrieve the filtering rules (2)
Figure 14 shows response for all active policies on the DOTS server.
{
"policy-data":[
{
"policy-id":123321333242,
"traffic-protocol": "tcp",
"source-protocol-port": "0-65535",
"destination-protocol-port": "443",
"destination-ip": "2001:db8:abcd:3f01::/64",
"source-ip": "2002:db8:6401::1",
"lifetime": 1800,
"traffic-rate": 0,
"match-count": 689324,
},
{
"policy-id":123321333242,
"traffic-protocol": "udp",
"source-protocol-port": "0-65535",
"destination-protocol-port": "53",
"destination-ip": "2001:db8:abcd:3f01::/64",
"source-ip": "2002:db8:6401::2",
"lifetime": 1800,
"traffic-rate": 0,
"match-count": 6666,
}
]
}
Figure 14: Response body
If the DOTS server does not find the policy number conveyed in the GET request in its policy state data, then it responds with a 4.04 (Not Found) error response code.
TODO
[TBD: DOTS WG will probably have to do something similar to https://tools.ietf.org/html/rfc7519#section-10, create JSON DOTS claim registry and register the JSON attributes defined in this specification].
Authenticated encryption MUST be used for data confidentiality and message integrity. TLS based on client certificate MUST be used for mutual authentication. 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.
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.
Special care should be taken in order to ensure that the activation of the proposed mechanism won't have an impact on the stability of the network (including connectivity and services delivered over that network).
Involved functional elements in the cooperation system must establish exchange instructions and notification over a secure and authenticated channel. Adequate filters can be enforced to avoid that nodes outside a trusted domain can inject request such as deleting filtering rules. Nevertheless, attacks can be initiated from within the trusted domain if an entity has been corrupted. Adequate means to monitor trusted nodes should also be enabled.
Thanks to Christian Jacquenet, Roland Dobbins, Andrew Mortensen, Roman Danyliw, and Gilbert Clark for the discussion and comments.