Distributed Denial-of-Service Open
Threat Signaling (DOTS) Data ChannelCisco Systems, Inc.Cessna Business Park, Varthur HobliSarjapur Marathalli Outer Ring RoadBangaloreKarnataka560103Indiatireddy@cisco.comOrangeRennes35000Francemohamed.boucadair@orange.comNTT CommunicationsGranPark 16F 3-4-1 Shibaura, Minato-kuTokyo108-8118Japankaname@nttv6.jpHuawei101 Software Avenue, Yuhuatai DistrictNanjing, Jiangsu210012Chinafrank.xialiang@huawei.comCisco Systems, Inc.praspati@cisco.comDOTSThe 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.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.DDoS Open Threat Signaling (DOTS) defines two channels: signal and
data channels (). 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 . The DOTS data channel is
used for infrequent bulk data exchange between DOTS agents in the aim to
significantly augment attack response coordination. | |
| DOTS Client | | DOTS Server |
| | <======= Data Channel ======> | |
+---------------+ +---------------+]]>Section 2 of
identifies that the DOTS data channel is used to perform the tasks
listed below:Filter management, which enables a DOTS client to install or
remove traffic filters dropping or rate-limiting unwanted traffic
and permitting white-listed traffic. Sample use cases for populating
black- or white-list filtering rules are detailed hereafter: If a network resource (DOTS client) detects a potential DDoS
attack from a set of IP addresses, the DOTS client informs its
servicing router (DOTS gateway) of all suspect IP addresses that
need to be blocked or black-listed for further investigation.
The DOTS client could also specify a list of protocols and ports
in the black-list rule. That DOTS gateway in-turn propagates the
black-listed IP addresses to the DOTS server which will
undertake appropriate action so that traffic from these IP
addresses to the target network (specified by the DOTS client)
is blocked.An enterprise network has partner sites from which only
legitimate traffic arrives and the enterprise network wants to
ensure that the traffic from these sites is not penalized during
DDOS attacks. The DOTS client uses DOTS data channel to convey
the white-listed IP addresses or prefixes of the partner sites
to its DOTS server. The DOTS server uses this information to
white-list flows from such IP addresses or prefixes reaching the
enterprise network.Creating identifiers, such as names or aliases, for resources for
which mitigation may be requested:The DOTS client may submit to the DOTS server a collection of
prefixes it wants to refer to by alias when requesting
mitigation, to which the server would respond with a success
status and the new prefix group alias, or an error status and
message in the event the DOTS client's data channel request
failed (see requirement OP-006 in and Section 2 in
).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 .The reader should be familiar with the terms defined in .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. RESTCONF over TLS over TCP is used for DOTS data channel (). RESTCONF uses HTTP methods to provide CRUD
operations on a conceptual datastore containing YANG-defined data, which
is compatible with a server which implements NETCONF datastores.JavaScript Object Notation (JSON)
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. This
specification uses the encoding rules defined in for representing DOTS data channel
configuration data defined using YANG () as
JSON text.All data channel URIs defined in this document, and in subsequent
documents, MUST NOT have a URI containing "/DOTS-signal".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 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.This document defines a YANG data
model for creating identifers, such as names or aliases, for
resources for which 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.This document defines the YANG module
"ietf-dots-data-channel-identifier", which has the following
structure: file "ietf-dots-data-channel-identifier@2016-11-28.yang"
module ietf-dots-data-channel-identifier {
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-data-channel-identifier";
prefix "alias";
import ietf-inet-types {
prefix "inet";
}
organization "Cisco Systems, Inc.";
contact "Tirumaleswar Reddy ";
description
"This module contains YANG definition for
configuring identifiers for resources using DOTS data channel";
revision 2016-11-28 {
reference
"https://tools.ietf.org/html/draft-reddy-dots-data-channel";
}
container identifier {
description "top level container for identifiers";
leaf policy-id {
type int32;
description "policy identifier";
}
list alias {
key alias-name;
description "list of identifiers";
leaf alias-name {
type string;
description "alias name";
}
leaf-list ip {
type inet:ip-address;
description "IP address";
}
leaf-list prefix {
type inet:ip-prefix;
description "prefix";
}
list port-range {
key "lower-port upper-port";
description "Port range. When only lower-port is present,
it represents a single port.";
leaf lower-port {
type inet:port-number;
mandatory true;
description "lower port";
}
leaf upper-port {
type inet:port-number;
must ". >= ../lower-port" {
error-message
"The upper-port must be greater than or
equal to lower-port";
}
description "upper port";
}
}
leaf-list traffic-protocol {
type uint8;
description "Internet Protocol number";
}
leaf-list FQDN {
type inet:domain-name;
description "FQDN";
}
leaf-list URI {
type inet:uri;
description "URI";
}
leaf-list E.164 {
type string;
description "E.164 number";
}
}
}
}
]]>This document uses the Access Control List (ACL) YANG data model
for the
configuration of filtering rules. ACL is explained in Section 1 of
. Examples of such configuration include:Black-list management, which enables a DOTS client to inform
the DOTS server about sources to suppress.White-list management, which enables a DOTS client to inform
the DOTS server about sources from which traffic should always
be accepted.Filter management, which enables a DOTS client to install or
remove traffic filters dropping or rate-limiting unwanted
traffic.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
().The header parameters are described below:Identifier of the policy represented
using an integer. This identifier MUST be unique for each policy
bound to the DOTS client, i.e., the policy-id needs to be unique
relative to the active policies with the DOTS server. This
identifier MUST be generated by the client. This document does
not make any assumption about how this identifier is generated.
This is a mandatory attribute.Name of the alias. This is a mandatory
attribute.Internet Protocol numbers. This
is an optional attribute.The port range, lower-port for lower
port number and upper-port for upper port number. For TCP, UDP,
SCTP, or DCCP: the range of ports (e.g., 80 to 8080). This is an
optional attribute.IP addresses are separated by commas. This is
an optional attribute.Prefixes are separated by commas. This is
an optional attribute.Fully Qualified Domain Name, is the full
name of a system, rather than just its hostname. For example,
"venera" is a hostname, and "venera.isi.edu" is an FQDN. This is
an optional attribute.Uniform Resource Identifier (URI). This is
an optional attribute.E.164 number. This is an optional
attribute.In the POST request at least one of the attributes
traffic-protocol or port-range or ip or prefix or FQDN or URI or
E.164 MUST be present. shows a POST request to create
alias called "https1" for HTTP(S) servers with IP addresses
2002:db8:6401::1 and 2002:db8:6401::2 listening on port 443.The DOTS server indicates the result of processing the POST
request using HTTP response codes. HTTP 2xx codes are success, HTTP
4xx codes are some sort of invalid requests and 5xx codes are
returned if the DOTS server has erred or it is incapable of
accepting the alias. Response code 201 (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 400 (Bad
Request) will be returned in the response or if the request contains
invalid or unknown parameters then 400 (Invalid query) will be
returned in the response. The HTTP response will include the JSON
body received in the request.A DELETE request is used to delete identifiers maintained by a
DOTS server ().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
404 (Not Found) error response code. The DOTS server successfully
acknowledges a DOTS client's request to remove the identifier using
204 (No Content) in the response.A GET request is used to retrieve the set of installed
identifiers from a DOTS server. shows how to retrieve all the
identifiers that were instantiated by the DOTS client while shows how to retrieve a specific
identifier. shows response for all identifiers
on the DOTS server.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 HTTP requests
to the DOTS gateway. The DOTS gateway validates the rules in the
requests and proxies the requests containing the filtering rules to a
DOTS server. When the DOTS gateway receives the associated HTTP
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.
shows a POST request to block traffic
from 10.10.10.1/24, destined to 11.11.11.1/24. The ACL JSON
configuration for the filtering rule is generated using the ACL YANG
data model defined in and the ACL configuration
XML for the filtering rule is specified in Section 4.3 of . The header parameters defined in are discussed below:The name of access-list. This is a
mandatory attribute.Indicates the primary intended type of
match criteria (e.g. IPv4, IPv6). This is a mandatory
attribute.Internet Protocol numbers. This is an
optional attribute.The source IPv4 prefix. This
is an optional attribute.The destination IPv4
prefix. This is an optional attribute."deny" or "permit". This is an optional
attribute.The DOTS server indicates the result of processing the POST
request using HTTP response codes. HTTP 2xx codes are success, HTTP
4xx codes are some sort of invalid requests and 5xx codes are
returned if the DOTS server has erred or it is incapable of
configuring the filtering rules. Response code 201 (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 400 (Bad Request) will be returned in the response
or if the request contains invalid or unknown parameters then 400
(Invalid query) will be returned in the response.A DELETE request is used to delete filtering rules from a DOTS
server ().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
404 (Not Found) error response code. The DOTS server successfully
acknowledges a DOTS client's request to withdraw the filtering rules
using 204 (No Content) 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. shows how to retrieve all the
filtering rules programmed by the DOTS client while shows how to retrieve specific filtering
rules programmed by the DOTS client.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
404 (Not Found) error response code.TODO[TBD: DOTS WG will have to do something similar to
https://tools.ietf.org/html/rfc7519#section-10, and create JSON DOTS
claim registry and register the JSON attributes defined in this
specification].The following individuals have contributed to this document:Dan Wing Email: dwing-ietf@fuggles.comAuthenticated 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 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 . 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.