INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 Management Information Base for Data Over Cable Service Interface Specification (DOCSIS) Cable Modem Termination Systems for Subscriber Management draft-ietf-ipcdn-subscriber-mib-10.txt Thu Feb 27 15:00:00 EST 2003 Wilson Sawyer ARRIS wsawyer@ieee.org Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at: http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at: http://www.ietf.org/shadow.html. Abstract This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it defines a set of managed objects for SNMP-based management of Data-over-Cable Service Interface Specification (DOCSIS)-compliant Cable Modem Termination Systems. These managed objects facilitate protection of the cable network from misuse by subscribers. This memo is a product of the IPCDN working group within the Internet Engineering Task Force. Comments are solicited and should be addressed to the working group's mailing list at ipcdn@ietf.org and/or the author. Expires August 2003 [Page 1] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 Table of Contents 1. The Internet-Standard Management Framework.........................2 2. Overview...........................................................2 2.1. Structure of the MIB.............................................3 2.2. Management requirements..........................................4 2.2.1. Interaction with DOCSIS provisioning for CPE address control...4 2.2.2. Interaction with DOCSIS provisioning for filtering.............5 2.2.3. Distinguishing Modem from Subscriber Traffic...................5 2.2.4. Row Existence of docsSubMgtTcpUdpFilterTable...................6 2.2.5. Filtering and the Tiny Fragment Attack.........................6 3. Definitions........................................................6 4. Acknowledgments...................................................24 5. Normative References..............................................24 6. Informative References............................................25 7. Security Considerations...........................................25 8. Author's Address..................................................27 9. Intellectual Property.............................................27 10. Full Copyright Statement.........................................27 1. The Internet-Standard Management Framework For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 [RFC3410]. Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580 [RFC2580]. 2. Overview This MIB provides a set of objects required for the management of DOCSIS Cable Modem Termination Systems (CMTS). The specification is derived in part from the operational model described in the DOCSIS Radio Frequency Interface Specification [DOCSRFI]. These managed objects facilitate protection of the cable network from misuse by subscribers. The following figure illustrates the operational and physical deployment relationships between elements in a cable modem network. This MIB resides at the CMTS, which is the first point in the public data network at which the cable operator controls physical access. The CMTS (possibly assisted by other IP services devices) acts as a network edge, separating the physical outside-plant cable television network from the operator's IP network. Expires August 2003 [Page 2] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 | operator's IP network +------+ --------------------- | CMTS | operator's cable head-end +------+ --------------------- | +--------+--------+ CATV physical network | | | +----+ +----+ +----+ ------------------ | CM | | CM | | CM | subscriber premises +----+ +----+ +----+ ------------------ | | | subscriber host or network This MIB controls IP packet forwarding to and from each cable modem, at the CMTS. Different modems may be accorded different treatment. Much of this MIB duplicates capabilities found in the DOCSIS Cable Device MIB [RFC2669]. While it is expected that the Cable Device MIB will be used to prevent unwanted traffic from entering the cable network, it is also possible that a malicious user might tamper with cable modem software, disabling its filtering policies. This MIB provides a more secure mechanism, since physical access to the CMTS is controlled by the network operator. In particular, this MIB provides two capabilities: first, to limit the IP addresses behind a modem, and, second, to provide protocol filtering to and from a modem. The first duplicates the capabilities of the docsDevCpe group [RFC2669]. This provides for either learned or provisioned subscriber premises host IP addresses behind a cable modem. The filtering capability is similar to that provided in docsDevFilter [RFC2669]. It differs from docsDevFilter in several respects, since it is intended to control subscriber traffic at the CMTS, rather than at the individual CM. First, its capabilities are streamlined to allow for either fast-software-based or hardware-assisted implementations, allowing for the greater number of packets that must be processed by the CMTS. Second, the MIB structure itself must add indexing at the CMTS to indicate which cable modem subscriber is intended. Third, rather than maintaining a separate list of filters for each modem at the CMTS, it is assumed that large numbers of modems will share filtering characteristics. Therefore, modems are grouped so as to share common filter lists. 2.1. Structure of the MIB This MIB is structured in five tables: o The docsSubMgtCpeControlTable controls the acceptance of subscriber host addresses behind a cable modem. o The docsSubMgtCpeIpTable monitors the subscriber host addresses which the CMTS believes to exist behind the cable modem. Expires August 2003 [Page 3] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 o The docsSubMgtPktFilterTable specifies filtering criteria which can be applied to packets destined to or originating from a cable modem. o The docsSubMgtTcpUdpFilterTable augments docsSubMgtPktFilterTable with optional TCP or UDP port filtering criteria. o The docsSubMgtCmFilterTable binds a cable modem to an ordered list of filters from docsSubMgtPktFilterTable. The docsSubMgtCpeControlTable and docsSubMgtCmFilterTable AUGMENT the docsIfCmtsCmStatusTable from [RFC2670]. Similarly, docsSubMgtCpeIpTable expands this table (an additional index is used). As such, each entry in these tables is bound to a registered cable modem, as perceived by the CMTS. The docsSubMgtPktFilterTable uses two indices. The first identifies the group to which a cable modem may be bound. The second is the ordering of filter criteria within each group. Any number of modems may be bound to the same group. 2.2. Management requirements The DOCSIS cable modem provisioning model [DOCSRFI] requires that cable modems use TFTP to acquire a list of parameters. The modem then passes many of these parameters to the CMTS in the DOCSIS Registration message. The parameter values are digitally signed by the creator of the TFTP contents, and the signature is verified by the CMTS. In general, then, the CMTS need not itself be configured with the attributes of its cable modems. It will acquire these values through the Registration process that is secured by the digital signature. Cable modem subscriber management, as described here, modifies this process slightly for reasons of data reduction and ease of administrative control. In the case of filtering management, for example, the tables are maintained through SNMP at the CMTS, and the modem registration merely signals the index values for the rows that apply to that modem. 2.2.1. Interaction with DOCSIS provisioning for CPE address control Rows in docsSubMgtCpeControlTable are created by the CMTS for each modem as a result of the DOCSIS registration process. The DOCSIS registration attributes may include items semantically equivalent to those in the DocsDevCpe branch of the DOCSIS Cable Device MIB [RFC2669]: o docsDevCpeEnroll o docsDevCpeIpMax o docsDevCpeIp Expires August 2003 [Page 4] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 Successful DOCSIS registration shall have the effect of setting the corresponding fields in the docsSubMgtCpeControlTable and the docsSubMgtCpeIpTable. If not present, the default at registration shall be to set docsSubMgtCpeControlActive to false. Rows in docsSubMgtCpeIpTable are created through any of three ways: DOCSIS registration (as described above), learning by the CMTS, or through some unspecified administrative mechanism on the CMTS. The docsDevCpeIpMax table bound applies only to the first two. The CMTS may learn addresses by simply snooping source IP addresses from each cable modem. Other learning mechanisms (for example, ARP snooping) may be used. The learning mechanism is not defined by this document. 2.2.2. Interaction with DOCSIS provisioning for filtering Rows in docsSubMgtCmFilterTable are created by the CMTS for each modem as a result of the DOCSIS registration process. The DOCSIS registration attributes may include four indices: o one identifying the upstream filter group for packets originating from the cable modem (i.e., those packets whose source MAC address matches that of the cable modem). o one identifying the upstream filter group for packets originating from subscribers attached to the cable modem (i.e., those packets whose source MAC address does not match that of the cable modem). o one identifying the downstream filter group for packets destined to the cable modem (i.e., those packets whose destination MAC address matches that of the cable modem). o one identifying the downstream filter group for packets destined to subscribers attached to the cable modem (i.e., those packets whose destination MAC address does not match that of the cable modem). Successful registration shall have the effect of setting docsSubMgtCmFilterDownstream, docsSubMgtCmFilterUpstream, docsSubMgtSubFilterDownstream, and docsSubMgtSubFilterUpstream, for that modem (just as if set through the SNMP protocol). If the DOCSIS attributes are not present, the effect shall be to set the modem's filter groups to the values of docsSubMgtCmFilterUpDefault, docsSubMgtCmFilterDownDefault, docsSubMgtSubFilterUpDefault, and docsSubMgtSubFilterDownDefault. 2.2.3. Distinguishing Modem from Subscriber Traffic All traffic originating from or destined to a subscriber site is potentially suspect, and subject to suppression by the network operator. This is true even if the traffic is ostensibly sourced or sunk by the cable modem itself, rather than the subscriber hosts behind the modem. To provide more nuanced administrative control, this document allows separate filter policies for modems and hosts. Expires August 2003 [Page 5] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 For example, modem policies may limit modems to server-subnet-only access, while allowing a different scope to subscribers. The CMTS chooses the filter set to apply based solely on the MAC address (source MAC upstream, destination MAC downstream). If the MAC address matches that of the modem, then the docsSubMgtCmFilterUp/Downstream pair is used; otherwise the docsSubMgtSubFilterUp/Downstream pair is applied. If the CM acts as a router rather than as a DOCSIS bridging forwarder, then the network operator will only use the docsSubMgtCmFilterUp/Downstream pair. 2.2.4. Row Existence of docsSubMgtTcpUdpFilterTable The docsSubMgtTcpUdpFilterTable exists apart from the docsSubMgtPktFilterTable because its filtering criteria is expected to be applied to a minority of modems relative to docsSubMgtPktFilterTable. It is separate in order to emphasize this expectation to both CMTS vendors and network operators. The rules for row creation are: o Row creation in docsSubMgtTcpUdpFilterTable is disallowed unless the corresponding row in docsSubMgtPktFilterTable already exists (or that row is being created simultaneously in the same SNMP SET message). o Deletion of the row in docsSubMgtPktFilterTable deletes the corresponding row in docsSubMgtTcpUdpFilterTable. o Row creation for docsSubMgtPktFilterTable does not create the corresponding row in docsSubMgtTcpUdpFilterTable. o Row deletion of docsSubMgtTcpUdpFilterTable does not delete the corresponding row in docsSubMgtPktFilterTable. 2.2.5. Filtering and the Tiny Fragment Attack It is recommended that the implementers prevent the "tiny fragment" and "overlapping fragment" attacks for the TCP filtering tables in this MIB, as discussed in RFC 1858 [RFC1858] and RFC 3128 [RFC3128]. Prevention of these attacks can be implemented with the following rules, when filtering is enabled: o admit all packets with fragment offset >= 2 o discard all packets with fragment offset = 1, or with fragment offset = 0 AND fragment payload length < 16. o apply filtering rules to all packets with fragment offset = 0. 3. Definitions Expires August 2003 [Page 6] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 DOCS-IETF-SUBMGT-MIB DEFINITIONS ::= BEGIN IMPORTS MODULE-IDENTITY, OBJECT-TYPE, Counter32, Integer32, mib-2 -- , BITS FROM SNMPv2-SMI RowStatus, TruthValue, TimeStamp, StorageType FROM SNMPv2-TC OBJECT-GROUP, MODULE-COMPLIANCE FROM SNMPv2-CONF InetAddressType, InetAddress, InetAddressPrefixLength, InetPortNumber FROM INET-ADDRESS-MIB Dscp FROM DIFFSERV-DSCP-TC docsIfCmtsCmStatusIndex, docsIfCmtsCmStatusEntry FROM DOCS-IF-MIB; -- RFC2670 docsSubMgt MODULE-IDENTITY LAST-UPDATED "200302270000Z" -- February 27, 2003 ORGANIZATION "IETF IPCDN Working Group" CONTACT-INFO " Wilson Sawyer Postal: ARRIS 6 Riverside Drive Andover, MA 01810 U.S.A. Phone: +1 978 946 4711 E-mail: wsawyer@ieee.org IETF IPCDN Working Group General Discussion: ipcdn@ietf.org Subscribe: http://www.ietf.org/mailman/listinfo/ipcdn Archive: ftp://ftp.ietf.org/ietf-mail-archive/ipcdn Co-chairs: Richard Woundy, rwoundy@broadband.att.com Jean-Francois Mule, jf.mule@cablelabs.com" DESCRIPTION "This is the CMTS centric subscriber management MIB for DOCSIS compliant CMTS. Copyright (C) The Internet Society (2003). This version of this MIB module is part of RFC xxxx; see the RFC itself for full legal notices." REVISION "200302270000Z" -- February 27, 2003 Expires August 2003 [Page 7] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 DESCRIPTION "Initial version, published as RFC xxxx." -- RFC editor to assign xxxx ::= { mib-2 xx } -- xx to be assigned by IANA docsSubMgtObjects OBJECT IDENTIFIER ::= { docsSubMgt 1 } docsSubMgtCpeControlTable OBJECT-TYPE SYNTAX SEQUENCE OF DocsSubMgtCpeControlEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "This table AUGMENTs the docsIfCmtsCmStatusTable and adds four WRITEable objects which reflect the state of subscriber management on a particular CM." ::= { docsSubMgtObjects 1 } docsSubMgtCpeControlEntry OBJECT-TYPE SYNTAX DocsSubMgtCpeControlEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A row in the docsSubMgtCpeControlTable. All values are set at successful modem registration, either from the system default, or from objects included in the DOCSIS registration request sent upstream to the CMTS from the CM. The contents of this entry are meaningless unless the corresponding docsIfCmtsCmStatusValue is registrationComplete(6). The persistence of this row is determined solely by the lifespan of the corresponding docsIfCmtsCmStatusEntry (normally StorageType=volatile)." AUGMENTS { docsIfCmtsCmStatusEntry } ::= {docsSubMgtCpeControlTable 1 } DocsSubMgtCpeControlEntry ::= SEQUENCE { docsSubMgtCpeControlMaxCpeIp Integer32, docsSubMgtCpeControlActive TruthValue, docsSubMgtCpeControlLearnable TruthValue, docsSubMgtCpeControlReset TruthValue, docsSubMgtCpeControlLastReset TimeStamp } docsSubMgtCpeControlMaxCpeIp OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "The number of simultaneous IP addresses permitted behind the CM. If this is set to zero, all CPE traffic from the CM is dropped. If the provisioning object corresponding to docsSubMgtCpeIpTable includes more CPE IP address entries for this modem than the value of this object, then this object is Expires August 2003 [Page 8] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 set to the count of the number of rows in docsSubMgtCpeIpTable that have the same docsIfCmtsCmStatusIndex value. (E.g. if the CM has 5 IP addresses specified for it, this value is 5). This limit applies to learned and docsis-provisioned entries, but does not limit entries added through some administrative process at the CMTS. If not set through DOCSIS provisioning, this object defaults to docsSubMgtCpeMaxIpDefault. Note that this object is only meaningful if docsSubMgtCpeControlActive is true." ::= { docsSubMgtCpeControlEntry 1 } docsSubMgtCpeControlActive OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-write STATUS current DESCRIPTION "If this is set to true, CMTS based CPE control is active and all the actions required by the various filter tables and controls apply at the CMTS. If this is set to false, no subscriber management filtering is done at the CMTS (but other filters may apply). If not set through DOCSIS provisioning, this object defaults to docsSubMgtCpeActiveDefault." ::= { docsSubMgtCpeControlEntry 2 } docsSubMgtCpeControlLearnable OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-write STATUS current DESCRIPTION "If this is set to true, the CMTS may learn up to docsSubMgtMaxCpeIp addresses (less any DOCSIS-provisioned entries) related to this CM. Those IP addresses are added (by internal process) to the docsSubMgtCpeIpTable. The nature of the learning mechanism is not specified here. If not set through DOCSIS provisioning, this object defaults to docsSubMgtCpeLearnableDefault. Note that this object is only meaningful if docsSubMgtCpeControlActive is true." ::= { docsSubMgtCpeControlEntry 3 } docsSubMgtCpeControlReset OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-write STATUS current DESCRIPTION "This object always returns false on read. If this object is set to true, the rows with 'learned' addresses in docsSubMgtCpeIpTable for this CM are deleted from that table." ::= { docsSubMgtCpeControlEntry 4 } docsSubMgtCpeControlLastReset OBJECT-TYPE SYNTAX TimeStamp MAX-ACCESS read-only STATUS current Expires August 2003 [Page 9] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 DESCRIPTION "The value of sysUpTime when docsSubMgtCpeControlReset was last set true. Zero if never reset." ::= { docsSubMgtCpeControlEntry 5 } docsSubMgtCpeMaxIpDefault OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "The default value for docsSubMgtCpeControlMaxCpeIp if not signaled in the DOCSIS Registration request. Upon initial CMTS initialization, this defaults to 16." ::= { docsSubMgtObjects 2 } docsSubMgtCpeActiveDefault OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-write STATUS current DESCRIPTION "The default value for docsSubMgtCpeControlActive if not signaled in the DOCSIS Registration request. Upon initial CMTS initialization, this defaults to false." ::= { docsSubMgtObjects 3 } docsSubMgtCpeLearnableDefault OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-write STATUS current DESCRIPTION "The default value for docsSubMgtCpeControlLearnable if not signaled in the DOCSIS Registration request. Upon initial CMTS initialization, this defaults to true." ::= { docsSubMgtObjects 4 } docsSubMgtCpeIpTable OBJECT-TYPE SYNTAX SEQUENCE OF DocsSubMgtCpeIpEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of CPE IP addresses known on a per CM basis." ::= { docsSubMgtObjects 5 } docsSubMgtCpeIpEntry OBJECT-TYPE SYNTAX DocsSubMgtCpeIpEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry in the docsSubMgtCpeIpTable. The first index is the specific modem we're referring to, the second index is the specific CPE IP entry." INDEX { docsIfCmtsCmStatusIndex, docsSubMgtCpeIpIndex } Expires August 2003 [Page 10] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 ::= {docsSubMgtCpeIpTable 1 } DocsSubMgtCpeIpEntry ::= SEQUENCE { docsSubMgtCpeIpIndex Integer32, docsSubMgtCpeIpAddressType InetAddressType, docsSubMgtCpeIpAddr InetAddress, docsSubMgtCpeIpLearned TruthValue } docsSubMgtCpeIpIndex OBJECT-TYPE SYNTAX Integer32(1..2147483647) MAX-ACCESS not-accessible STATUS current DESCRIPTION "The index of this CPE IP address relative to the indexed CM. An entry is created either through the included CPE IP addresses in the provisioning object, or via learning. If a CMTS receives an IP packet from a CM that contains a source IP address which does not match one of the docsSubMgtCpeIpAddr entries for this CM, one of two things occurs. If the number of entries is less than docsSubMgtCpeControlMaxCpeIp, the source address is added to the table and the packet is forwarded. If the number of entries equals the docsSubMgtCpeControlMaxCpeIp, AND docsSubMgtCpeControlActive is true, then the packet is dropped. Otherwise the packet is forwarded. " ::= { docsSubMgtCpeIpEntry 1 } docsSubMgtCpeIpAddressType OBJECT-TYPE SYNTAX InetAddressType MAX-ACCESS read-only STATUS current DESCRIPTION "The type of internet address of docsSubMgtCpeIpAddr." ::= { docsSubMgtCpeIpEntry 2 } docsSubMgtCpeIpAddr OBJECT-TYPE SYNTAX InetAddress MAX-ACCESS read-only STATUS current DESCRIPTION "The IP address either set from provisioning or learned via address gleaning or other forwarding means. See docsSubMgtCpeIpIndex for the mechanism." ::= { docsSubMgtCpeIpEntry 3 } docsSubMgtCpeIpLearned OBJECT-TYPE SYNTAX TruthValue MAX-ACCESS read-only STATUS current DESCRIPTION "If true, this entry was learned from IP packets sent Expires August 2003 [Page 11] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 upstream rather than from the provisioning objects." ::= { docsSubMgtCpeIpEntry 4 } -- The generic packet filter table. Note that this just defines the -- match criteria. The docsSubMgtCmFilterTable links this table to -- the specific modems. docsSubMgtPktFilterTable OBJECT-TYPE SYNTAX SEQUENCE OF DocsSubMgtPktFilterEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "A table of filter or classifier criteria. Classifiers are assigned by group to the individual CMs. That assignment is made via the configuration objects sent upstream from the CM to the CMTS during registration. Each filter in the group is applied in index order to each packet. If the filter matches, then the indicated action is taken. If no filter matches then the packet is accepted for further processing." ::= { docsSubMgtObjects 6 } docsSubMgtPktFilterEntry OBJECT-TYPE SYNTAX DocsSubMgtPktFilterEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "An entry in the docsSubMgtPktFilterTable." INDEX { docsSubMgtPktFilterGroup, docsSubMgtPktFilterIndex } ::= {docsSubMgtPktFilterTable 1 } DocsSubMgtPktFilterEntry ::= SEQUENCE { docsSubMgtPktFilterGroup Integer32, docsSubMgtPktFilterIndex Integer32, docsSubMgtPktFilterAddrType InetAddressType, docsSubMgtPktFilterSrcAddr InetAddress, docsSubMgtPktFilterSrcMask InetAddressPrefixLength, docsSubMgtPktFilterDstAddr InetAddress, docsSubMgtPktFilterDstMask InetAddressPrefixLength, docsSubMgtPktFilterUlp Integer32, docsSubMgtPktFilterDscpValue Dscp, docsSubMgtPktFilterDscpMask Dscp, docsSubMgtPktFilterAction INTEGER, docsSubMgtPktFilterMatches Counter32, docsSubMgtPktFilterStatus RowStatus, docsSubMgtPktFilterStorageType StorageType } docsSubMgtPktFilterGroup OBJECT-TYPE SYNTAX Integer32(1..2147483647) MAX-ACCESS not-accessible Expires August 2003 [Page 12] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 STATUS current DESCRIPTION "Identifies an ordered group of filters. Each modem may be associated with a filter group for its upstream traffic (docsSubMgtCmFilterUpstream) and a filter group for its downstream traffic (docsSubMgtCmFilterDownstream). Typically, many modems will use the same filter group." ::= { docsSubMgtPktFilterEntry 1 } docsSubMgtPktFilterIndex OBJECT-TYPE SYNTAX Integer32(1..2147483647) MAX-ACCESS not-accessible STATUS current DESCRIPTION "An index which describes the ordering of a set of filter specifications within the group. Filters are applied in index order." ::= { docsSubMgtPktFilterEntry 2 } docsSubMgtPktFilterAddrType OBJECT-TYPE SYNTAX InetAddressType MAX-ACCESS read-create STATUS current DESCRIPTION "The type of internet address of docsSubMgtPktFilterSrcAddr, docsSubMgtPktFilterSrcMask, docsSubMgtPktFilterDstAddr, and docsSubMgtPktFilterDstMask." DEFVAL { ipv4 } ::= { docsSubMgtPktFilterEntry 3 } docsSubMgtPktFilterSrcAddr OBJECT-TYPE SYNTAX InetAddress MAX-ACCESS read-create STATUS current DESCRIPTION "The source IP address to match in the packet to be classified. By default, this is the all-zero's IP v4 and v6 address. A packet matches the SrcAddr filter if the following is true: AND (FilterSrcAddr, maskFrom(FilterSrcMask)) == AND (Packet SrcAddr, maskFrom(FilterSrcMask)) where maskFrom(N) is a bitmask constructed with N leftmost 1's bits. The mask value is applied to both the match value in this table and to the packet IP address. The address type of this object is specified by docsSubMgtPktFilterAddrType." DEFVAL { '00000000'H } -- 0.0.0.0 ::= { docsSubMgtPktFilterEntry 4 } docsSubMgtPktFilterSrcMask OBJECT-TYPE SYNTAX InetAddressPrefixLength MAX-ACCESS read-create STATUS current DESCRIPTION Expires August 2003 [Page 13] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 "Specifies the number of leftmost 1's bits in an address bit mask. The bit mask that is applied to the source address prior to matching. This, taken with the SrcAddr specifies a matching criteria. By default, the pair specifies a filter which matches all source addresses. The address type of this object is specified by docsSubMgtPktFilterAddrType." DEFVAL { 0 } ::= { docsSubMgtPktFilterEntry 5 } docsSubMgtPktFilterDstAddr OBJECT-TYPE SYNTAX InetAddress MAX-ACCESS read-create STATUS current DESCRIPTION "The destination IP address to match in the packet to be classified. By default, this is the all-zero's IP v4 and v6 address. A packet matches the DstAddr filter if the following is true: AND (FilterDstAddr, maskFrom(FilterDstMask)) == AND (Packet DstAddr, maskFrom(FilterDstMask)) where maskFrom(N) is a bitmask constructed with N leftmost 1's bits. The mask value is applied to both the match value in this table and to the packet IP address. The address type of this object is specified by docsSubMgtPktFilterAddrType." DEFVAL { '00000000'H } -- 0.0.0.0 ::= { docsSubMgtPktFilterEntry 6 } docsSubMgtPktFilterDstMask OBJECT-TYPE SYNTAX InetAddressPrefixLength MAX-ACCESS read-create STATUS current DESCRIPTION "Specifies the number of leftmost 1's bits in an address bit mask. The bit mask that is applied to the destination address prior to matching. This, taken with the DstAddr specifies a matching criteria. By default, the pair specifies a filter which matches all destination addresses. The address type of this object is specified by docsSubMgtPktFilterAddrType." DEFVAL { 0 } ::= { docsSubMgtPktFilterEntry 7 } docsSubMgtPktFilterUlp OBJECT-TYPE SYNTAX Integer32 (0..256) MAX-ACCESS read-create STATUS current DESCRIPTION "Upper level protocol to match. If this value is 256, matches ALL ULP values. Otherwise, this matches the specific protocol value. Note that if the packet ULP is either 6 (tcp) or 17 (udp), then docsSubMgtPktTcpUdpFilterTable must also be consulted (if its entry exists) to see if this entry matches. If this value is neither tcp(6) nor udp(17), then that table is not consulted." Expires August 2003 [Page 14] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 DEFVAL { 256 } ::= { docsSubMgtPktFilterEntry 8 } docsSubMgtPktFilterDscpValue OBJECT-TYPE SYNTAX Dscp MAX-ACCESS read-create STATUS current DESCRIPTION "The Differentiated Services Code Point (DSCP) value to match in the IP packet." DEFVAL { 0 } ::= { docsSubMgtPktFilterEntry 9 } docsSubMgtPktFilterDscpMask OBJECT-TYPE SYNTAX Dscp MAX-ACCESS read-create STATUS current DESCRIPTION "The mask to apply against the DSCP value to be matched in the IP packet. The default for both these objects taken together matches all DSCP values. A packet matches this filter if the following is true: AND (FilterDscpValue, FilterDscpMask) == AND (Packet DSCP Value, FilterDscpMask)." DEFVAL { 0 } ::= { docsSubMgtPktFilterEntry 10 } docsSubMgtPktFilterAction OBJECT-TYPE SYNTAX INTEGER { accept(1), drop(2) } MAX-ACCESS read-create STATUS current DESCRIPTION "The action to take upon this filter matching. Accept(1) means to end filter matching and to accept the packet for further processing. Drop(2) means to drop the packet." DEFVAL { accept } ::= { docsSubMgtPktFilterEntry 11 } docsSubMgtPktFilterMatches OBJECT-TYPE SYNTAX Counter32 MAX-ACCESS read-only STATUS current DESCRIPTION "This object counts the number of times this specific rule has been matched. This is incremented any time this rule is encountered and all components match. It is only incremented for the first (lowest-indexed) filter matching a packet." ::= { docsSubMgtPktFilterEntry 12 } Expires August 2003 [Page 15] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 docsSubMgtPktFilterStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "Standard rowStatus object for creating this row. Any object in this row which is writable may be changed at any time while the row is active. Since all writable objects in the entry have DEFVALs, a row may be made active without specifying any other values." ::= { docsSubMgtPktFilterEntry 13 } docsSubMgtPktFilterStorageType OBJECT-TYPE SYNTAX StorageType MAX-ACCESS read-create STATUS current DESCRIPTION "This object defines whether this filter is kept in volatile storage and lost upon reboot or if this row is backed up by non-volatile or permanent storage. 'permanent' entries need not allow writable access to any object." DEFVAL { nonVolatile } ::= { docsSubMgtPktFilterEntry 14 } docsSubMgtTcpUdpFilterTable OBJECT-TYPE SYNTAX SEQUENCE OF DocsSubMgtTcpUdpFilterEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "This is an adjunct to docsSubMgtPktFilterTable. It provides optional filtering based on elements in TCP or UDP headers. This table is separate from docsSubMgtPktFilterTable only because it is expected to be used more rarely. This table is not consulted unless the upper-layer protocol is TCP or UDP." ::= { docsSubMgtObjects 7 } docsSubMgtTcpUdpFilterEntry OBJECT-TYPE SYNTAX DocsSubMgtTcpUdpFilterEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Defines filtering criteria for TCP and UDP headers. Persistence of this row is controlled by docsSubMgtPktFilterStorageType." INDEX { docsSubMgtPktFilterGroup, docsSubMgtPktFilterIndex } ::= {docsSubMgtTcpUdpFilterTable 1 } DocsSubMgtTcpUdpFilterEntry ::= SEQUENCE { docsSubMgtTcpUdpSrcPort InetPortNumber, docsSubMgtTcpUdpDstPort InetPortNumber, docsSubMgtTcpFlagValues BITS, Expires August 2003 [Page 16] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 docsSubMgtTcpFlagMask BITS, docsSubMgtTcpUdpStatus RowStatus } docsSubMgtTcpUdpSrcPort OBJECT-TYPE SYNTAX InetPortNumber MAX-ACCESS read-create STATUS current DESCRIPTION "The source port to match. Zero matches any value in the TCP or UDP source port field." DEFVAL { 0 } ::= { docsSubMgtTcpUdpFilterEntry 1 } docsSubMgtTcpUdpDstPort OBJECT-TYPE SYNTAX InetPortNumber MAX-ACCESS read-create STATUS current DESCRIPTION "The destination port to match. Zero matches any value in the TCP or UDP destination port field." DEFVAL { 0 } ::= { docsSubMgtTcpUdpFilterEntry 2 } docsSubMgtTcpFlagValues OBJECT-TYPE SYNTAX BITS { urgent(0), ack(1), push(2), reset(3), syn(4), fin(5) } MAX-ACCESS read-create STATUS current DESCRIPTION "The value of the flags of interest. The value of this object MUST always be a subset (proper or otherwise) of docsSubMgtTcpFlagMask. An attempt to violate this constraint returns an inconsistentValue." DEFVAL { {} } ::= { docsSubMgtTcpUdpFilterEntry 3 } docsSubMgtTcpFlagMask OBJECT-TYPE SYNTAX BITS { urgent(0), ack(1), push(2), reset(3), syn(4), fin(5) Expires August 2003 [Page 17] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 } MAX-ACCESS read-create STATUS current DESCRIPTION "This bit set indicates the flags of interest in the TCP header for the packet to be matched. For example to match all packets where the urgent bit is set, but that are not either syn or fin, the value of docsSubMgtTcpFlagValues would be { urgent }, and the value of this object would be { urgent, syn, fin }" DEFVAL { {} } ::= { docsSubMgtTcpUdpFilterEntry 4 } docsSubMgtTcpUdpStatus OBJECT-TYPE SYNTAX RowStatus MAX-ACCESS read-create STATUS current DESCRIPTION "Standard row object for this table. Any object in the conceptual row may be modified regardless of whether this row is active or not. Since all writable objects in the entry have DEFVALs, a row may be made active without specifying any other values." ::= { docsSubMgtTcpUdpFilterEntry 5 } docsSubMgtCmFilterTable OBJECT-TYPE SYNTAX SEQUENCE OF DocsSubMgtCmFilterEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Binds filter groups to modems. This table identifies for each modem the upstream and downstream filter groups that apply to packets for that modem. Zero is used as a distinguished value to mean no filter group." ::= { docsSubMgtObjects 8 } docsSubMgtCmFilterEntry OBJECT-TYPE SYNTAX DocsSubMgtCmFilterEntry MAX-ACCESS not-accessible STATUS current DESCRIPTION "Binds a filter group to each direction of traffic for a modem. The filters in this entry apply if docsSubMgtCpeControlActive is true. The contents of this entry are meaningless unless the corresponding docsIfCmtsCmStatusValue is registrationComplete(6). The persistence of this row is determined solely by the lifespan of the corresponding docsIfCmtsCmStatusEntry (normally StorageType=volatile)." AUGMENTS { docsIfCmtsCmStatusEntry } ::= {docsSubMgtCmFilterTable 1 } DocsSubMgtCmFilterEntry ::= SEQUENCE { docsSubMgtSubFilterDownstream Integer32, Expires August 2003 [Page 18] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 docsSubMgtSubFilterUpstream Integer32, docsSubMgtCmFilterDownstream Integer32, docsSubMgtCmFilterUpstream Integer32 } docsSubMgtSubFilterDownstream OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "The filter group applied to traffic destined for subscribers attached to the referenced CM. This is set upon row creation to either the default (docsSubMgtSubFilterDownDefault), or to the value in the provisioning object sent upstream from the CM to the CMTS during registration. The value of this object is a pointer into the docsSubMgtPktFilterTable and refers to all filter rows with matching docsSubMgtPktFilterGroup indices. If there are no matching filter rows in that table, or if this object is set to zero, no filtering is applied to traffic destined to hosts attached to this CM." ::= { docsSubMgtCmFilterEntry 1 } docsSubMgtSubFilterUpstream OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "The filter group applied to traffic originating from subscribers attached to the referenced CM. This is set upon row creation to either the default (docsSubMgtSubFilterUpDefault), or to the value in the provisioning object sent upstream from the CM to the CMTS. The value of this object is a pointer into the docsSubMgtPktFilterTable and refers to all filter rows with matching docsSubMgtPktFilterGroup indices. If there are no matching filter rows in that table, or if this object is set to zero, no filtering is applied to traffic originating from hosts attached to this CM." ::= { docsSubMgtCmFilterEntry 2 } docsSubMgtCmFilterDownstream OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "The filter group applied to traffic destined for the referenced CM itself. This is set upon row creation to either the default (docsSubMgtCmFilterDownDefault), or to the value in the provisioning object sent upstream from the CM to the CMTS during registration. The value of this object is a pointer into the docsSubMgtPktFilterTable and refers to all filter rows with matching docsSubMgtPktFilterGroup indices. If there are no matching filter rows in that table, or if this object is set to zero, no filtering is applied to traffic destined to this CM." Expires August 2003 [Page 19] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 ::= { docsSubMgtCmFilterEntry 3 } docsSubMgtCmFilterUpstream OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "The filter group applied to traffic originating from the referenced CM itself. This is set upon row creation to either the default (docsSubMgtCmFilterUpDefault), or to the value in the provisioning object sent upstream from the CM to the CMTS. The value of this object is a pointer into the docsSubMgtPktFilterTable and refers to all filter rows with matching docsSubMgtPktFilterGroup indices. If there are no matching filter rows in that table, or if this object is set to zero, no filtering is applied to traffic originating from this CM." ::= { docsSubMgtCmFilterEntry 4 } docsSubMgtSubFilterDownDefault OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "Upon a row creation in docsSubMgtCmFilterTable, docsSubMgtSubFilterDownstream is set to this value if no provisioning object is present to override it. This object is persistent across CMTS reboots. Upon initial CMTS initialization, this defaults to 0." ::= { docsSubMgtObjects 9 } docsSubMgtSubFilterUpDefault OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "Upon a row creation in docsSubMgtCmFilterTable, docsSubMgtSubFilterUpstream is set to this value if no provisioning object is present to override it. This object is persistent across CMTS reboots. Upon initial CMTS initialization, this defaults to 0." ::= { docsSubMgtObjects 10 } docsSubMgtCmFilterDownDefault OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "Upon a row creation in docsSubMgtCmFilterTable, docsSubMgtCmFilterDownstream is set to this value if no provisioning object is present to override it. This object is persistent across CMTS reboots. Upon initial CMTS initialization, this defaults to 0." Expires August 2003 [Page 20] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 ::= { docsSubMgtObjects 11 } docsSubMgtCmFilterUpDefault OBJECT-TYPE SYNTAX Integer32(0..2147483647) MAX-ACCESS read-write STATUS current DESCRIPTION "Upon a row creation in docsSubMgtCmFilterTable, docsSubMgtCmFilterUpstream is set to this value if no provisioning object is present to override it. This object is persistent across CMTS reboots. Upon initial CMTS initialization, this defaults to 0." ::= { docsSubMgtObjects 12 } docsSubMgtConformance OBJECT IDENTIFIER ::= { docsSubMgt 2 } docsSubMgtCompliances OBJECT IDENTIFIER ::= { docsSubMgtConformance 1 } docsSubMgtGroups OBJECT IDENTIFIER ::= { docsSubMgtConformance 2 } docsSubMgtBasicCompliance MODULE-COMPLIANCE STATUS current DESCRIPTION "The compliance statement for CMTS devices that implement CMTS centric subscriber management." MODULE MANDATORY-GROUPS { docsSubMgtGroup } OBJECT docsSubMgtCpeControlMaxCpeIp SYNTAX Integer32(0..16) DESCRIPTION "An implementation is only required to support up to sixteen addresses per modem." OBJECT docsSubMgtCpeMaxIpDefault SYNTAX Integer32(0..16) DESCRIPTION "An implementation is only required to support up to sixteen addresses per modem." OBJECT docsSubMgtCpeIpAddressType SYNTAX InetAddressType { ipv4(1) } DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtCpeIpAddr SYNTAX InetAddress (SIZE(4)) Expires August 2003 [Page 21] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtPktFilterAddrType SYNTAX InetAddressType { ipv4(1) } DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtPktFilterSrcAddr SYNTAX InetAddress (SIZE(4)) DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtPktFilterSrcMask SYNTAX InetAddressPrefixLength(0..32) DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtPktFilterDstAddr SYNTAX InetAddress (SIZE(4)) DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtPktFilterDstMask SYNTAX InetAddressPrefixLength(0..32) DESCRIPTION "An implementation is only required to support IPv4 addresses." OBJECT docsSubMgtPktFilterStorageType SYNTAX StorageType { nonVolatile(3) } DESCRIPTION "An implementation is only required to support nonvolatile storage of filter entries." OBJECT docsSubMgtSubFilterDownstream SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtSubFilterUpstream SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtCmFilterDownstream Expires August 2003 [Page 22] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtCmFilterUpstream SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtSubFilterDownDefault SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtSubFilterUpDefault SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtCmFilterDownDefault SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." OBJECT docsSubMgtCmFilterUpDefault SYNTAX Integer32(0..30) DESCRIPTION "An implementation is only required to support thirty filter groups." ::= { docsSubMgtCompliances 1 } docsSubMgtGroup OBJECT-GROUP OBJECTS { docsSubMgtCpeControlMaxCpeIp, docsSubMgtCpeControlActive, docsSubMgtCpeControlLearnable, docsSubMgtCpeControlReset, docsSubMgtCpeControlLastReset, docsSubMgtCpeMaxIpDefault, docsSubMgtCpeActiveDefault, docsSubMgtCpeLearnableDefault, docsSubMgtCpeIpAddressType, docsSubMgtCpeIpAddr, docsSubMgtCpeIpLearned, docsSubMgtPktFilterAddrType, docsSubMgtPktFilterSrcAddr, docsSubMgtPktFilterSrcMask, Expires August 2003 [Page 23] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 docsSubMgtPktFilterDstAddr, docsSubMgtPktFilterDstMask, docsSubMgtPktFilterUlp, docsSubMgtPktFilterDscpValue, docsSubMgtPktFilterDscpMask, docsSubMgtPktFilterAction, docsSubMgtPktFilterMatches, docsSubMgtPktFilterStatus, docsSubMgtPktFilterStorageType, docsSubMgtTcpUdpSrcPort, docsSubMgtTcpUdpDstPort, docsSubMgtTcpFlagValues, docsSubMgtTcpFlagMask, docsSubMgtTcpUdpStatus, docsSubMgtSubFilterDownstream, docsSubMgtSubFilterUpstream, docsSubMgtCmFilterDownstream, docsSubMgtCmFilterUpstream, docsSubMgtSubFilterDownDefault, docsSubMgtSubFilterUpDefault, docsSubMgtCmFilterDownDefault, docsSubMgtCmFilterUpDefault } STATUS current DESCRIPTION "The objects use to managed host-based cable modems via a set of CMTS enforced controls." ::= { docsSubMgtGroups 1 } END 4. Acknowledgments This document is based on work by Michael St.Johns, then at Excite@Home. Thanks to Guenter Roeck and Julie McGray for reviewing early drafts. This draft benefitted from extensive review by Bert Wijnen. 5. Normative References [RFC2578] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Structure of Management Information for Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. [RFC2579] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Textual Conventions for SMIv2", STD 58, RFC 2579, April 1999. [RFC2580] McCloghrie, K., Perkins, D. and J. Schoenwaelder, "Conformance Statements for SMIv2", STD 58, RFC 2580, April 1999. Expires August 2003 [Page 24] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 [DOCSRFI] "Data-Over-Cable Service Interface Specifications: Cable Modem Radio Frequency Interface Specification SP-RFIv2.0-I02-020617", DOCSIS, June 2002, available at http://www.cablemodem.com/. [RFC2669] StJohns, M. , "Cable Device Management Information Base for DOCSIS Compliant Cable Modems and Cable Modem Termination Systems", RFC2669, August 1999. [RFC2670] StJohns, M. , "Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS compliant RF interfaces", RFC2670, August 1999. 6. Informative References [RFC1858] Ziemba, G., Reed, D., and P. Traina, "Security Considerations for IP Fragment Filtering", RFC1858, October 1995. [RFC3128] Miller, I., "Protection against a Variant of the Tiny Fragment Attack". RFC3128, June 2001. [RFC3410] Case, J., Mundy, R., Partain, D. and B. Stewart, "Introduction and Applicability Statements for Internet- Standard Management Framework", RFC 3410, December 2002. [DOCSBPI] "Data-Over-Cable Service Interface Specifications: Baseline Privacy Plus Interface Specification SP-BPI+-I09-020830", DOCSIS, August 2002, available at http://www.cablemodem.com/. 7. Security Considerations This MIB is intended to limit certain kinds of network behavior by subscriber hosts attached to cable modems, including, for example, IP spoofing. These limitations may be compromised, however, if the cable modem's identity or registration process is spoofed. The DOCSIS RFI and privacy specifications [DOCSRFI] and [DOCSBPI] define a number of mechanisms for assuring modem identity. The filtering mechanism defined here can be defeated through the "tiny fragment" and "overlapping fragment" attacks if the recommendations in section 2.2.6 are omitted. See [RFC1858] and [RFC3128] for discussion of these attacks. There are a number of management objects defined in this MIB that have a MAX-ACCESS clause of read-write and/or read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure Expires August 2003 [Page 25] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 environment without proper protection can have a negative effect on network operations. Unauthorized SETs to this MIB can permit two major security problems with public cable network operation: IP address spoofing, and defeat of operator-defined packet filtering. The following objects, if SET maliciously, would evade controls on address spoofing: docsSubMgtCpeControlMaxCpeIp docsSubMgtCpeControlActive docsSubMgtCpeControlLearnable docsSubMgtCpeControlReset docsSubMgtCpeMaxIpDefault docsSubMgtCpeActiveDefault docsSubMgtCpeLearnableDefault All writable objects in docsSubMgtPktFilterTable and docsSubMgtTcpUdpFilterTable share the potential, if SET maliciously, to permit unwanted and disruptive traffic to enter the public data network, as well as to be transmitted to subscribers. The following objects could also permit packet filtering to be defeated: docsSubMgtSubFilterDownstream docsSubMgtSubFilterUpstream docsSubMgtCmFilterDownstream docsSubMgtCmFilterUpstream docsSubMgtSubFilterDownDefault docsSubMgtSubFilterUpDefault docsSubMgtCmFilterDownDefault docsSubMgtCmFilterUpDefault Some of the readable objects in this MIB module (i.e., objects with a MAX-ACCESS other than not-accessible) may be considered sensitive or vulnerable in some network environments. It is thus important to control even GET access to these objects and possibly to even encrypt the values of these objects when sending them over the network via SNMP. The most sensitive is docsSubMgtCpeIpAddr within docsSubMgtCpeIpTable. While docsSubMgtCpeIpTable is intended to control address spoofing, it includes information about the current subscriber address pool. This information may itself be valuable to would-be spoofers. SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example by using IPSec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module. It is RECOMMENDED that implementers consider the security features as provided by the SNMPv3 framework (see [RFC3410], section 8), including full support for the SNMPv3 cryptographic mechanisms (for Expires August 2003 [Page 26] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 authentication and privacy). Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to an instance of this MIB module, is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them. 8. Author's Address Wilson Sawyer ARRIS 6 Riverside Drive Andover, MA 01810 USA Phone: +1 978 946 4711 Email: wsawyer@ieee.org 9. Intellectual Property The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 10. Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to Expires August 2003 [Page 27] INTERNET-DRAFT DOCSIS Subscriber Management MIB February 2003 others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Expires August 2003 [Page 28]