Network Working Group T. Chown
Request for Comments: 5157 University of Southampton
Category: Informational March 2008
Network Working Group T. Chown
Request for Comments: 5157 University of Southampton
Category: Informational March 2008
IPv6 Implications for Network Scanning
IPv6对网络扫描的影响
Status of This Memo
关于下段备忘
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
Abstract
摘要
The much larger default 64-bit subnet address space of IPv6 should in principle make traditional network (port) scanning techniques used by certain network worms or scanning tools less effective. While traditional network scanning probes (whether by individuals or automated via network worms) may become less common, administrators should be aware that attackers may use other techniques to discover IPv6 addresses on a target network, and thus they should also be aware of measures that are available to mitigate them. This informational document discusses approaches that administrators could take when planning their site address allocation and management strategies as part of a defence-in-depth approach to network security.
IPv6的默认64位子网地址空间大得多，原则上会降低某些网络蠕虫或扫描工具使用的传统网络（端口）扫描技术的效率。虽然传统的网络扫描探测（无论是由个人进行还是通过网络蠕虫自动进行）可能变得不太常见，但管理员应该意识到攻击者可能会使用其他技术来发现目标网络上的IPv6地址，因此他们还应该意识到可用于缓解这些攻击的措施。本信息性文档讨论了管理员在规划其站点地址分配和管理策略时可以采取的方法，作为网络安全纵深防御方法的一部分。
Table of Contents
目录
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Target Address Space for Network Scanning . . . . . . . . . . 4
2.1. IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Reducing the IPv6 Search Space . . . . . . . . . . . . . . 4
2.4. Dual-Stack Networks . . . . . . . . . . . . . . . . . . . 5
2.5. Defensive Scanning . . . . . . . . . . . . . . . . . . . . 5
3. Alternatives for Attackers: Off-Link . . . . . . . . . . . . . 5
3.1. Gleaning IPv6 Prefix Information . . . . . . . . . . . . . 5
3.2. DNS Advertised Hosts . . . . . . . . . . . . . . . . . . . 6
3.3. DNS Zone Transfers . . . . . . . . . . . . . . . . . . . . 6
3.4. Log File Analysis . . . . . . . . . . . . . . . . . . . . 6
3.5. Application Participation . . . . . . . . . . . . . . . . 6
3.6. Multicast Group Addresses . . . . . . . . . . . . . . . . 7
3.7. Transition Methods . . . . . . . . . . . . . . . . . . . . 7
4. Alternatives for Attackers: On-Link . . . . . . . . . . . . . 7
4.1. General On-Link Methods . . . . . . . . . . . . . . . . . 7
4.2. Intra-Site Multicast or Other Service Discovery . . . . . 8
5. Tools to Mitigate Scanning Attacks . . . . . . . . . . . . . . 8
5.1. IPv6 Privacy Addresses . . . . . . . . . . . . . . . . . . 9
5.2. Cryptographically Generated Addresses (CGAs) . . . . . . . 9
5.3. Non-Use of MAC Addresses in EUI-64 Format . . . . . . . . 10
5.4. DHCP Service Configuration Options . . . . . . . . . . . . 10
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
9. Informative References . . . . . . . . . . . . . . . . . . . . 11
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Target Address Space for Network Scanning . . . . . . . . . . 4
2.1. IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Reducing the IPv6 Search Space . . . . . . . . . . . . . . 4
2.4. Dual-Stack Networks . . . . . . . . . . . . . . . . . . . 5
2.5. Defensive Scanning . . . . . . . . . . . . . . . . . . . . 5
3. Alternatives for Attackers: Off-Link . . . . . . . . . . . . . 5
3.1. Gleaning IPv6 Prefix Information . . . . . . . . . . . . . 5
3.2. DNS Advertised Hosts . . . . . . . . . . . . . . . . . . . 6
3.3. DNS Zone Transfers . . . . . . . . . . . . . . . . . . . . 6
3.4. Log File Analysis . . . . . . . . . . . . . . . . . . . . 6
3.5. Application Participation . . . . . . . . . . . . . . . . 6
3.6. Multicast Group Addresses . . . . . . . . . . . . . . . . 7
3.7. Transition Methods . . . . . . . . . . . . . . . . . . . . 7
4. Alternatives for Attackers: On-Link . . . . . . . . . . . . . 7
4.1. General On-Link Methods . . . . . . . . . . . . . . . . . 7
4.2. Intra-Site Multicast or Other Service Discovery . . . . . 8
5. Tools to Mitigate Scanning Attacks . . . . . . . . . . . . . . 8
5.1. IPv6 Privacy Addresses . . . . . . . . . . . . . . . . . . 9
5.2. Cryptographically Generated Addresses (CGAs) . . . . . . . 9
5.3. Non-Use of MAC Addresses in EUI-64 Format . . . . . . . . 10
5.4. DHCP Service Configuration Options . . . . . . . . . . . . 10
6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
9. Informative References . . . . . . . . . . . . . . . . . . . . 11
One of the key differences between IPv4 and IPv6 is the much larger address space for IPv6, which also goes hand-in-hand with much larger subnet sizes. This change has a significant impact on the feasibility of TCP and UDP network scanning, whereby an automated process is run to detect open ports (services) on systems that may then be subject to a subsequent attack. Today many IPv4 sites are subjected to such probing on a recurring basis. Such probing is common in part due to the relatively dense population of active hosts in any given chunk of IPv4 address space.
IPv4和IPv6之间的一个关键区别是IPv6的地址空间大得多，这也与更大的子网大小密切相关。这一变化对TCP和UDP网络扫描的可行性产生了重大影响，通过自动过程检测系统上的开放端口（服务），然后这些端口（服务）可能会受到后续攻击。今天，许多IPv4站点经常受到这样的探测。这种探测之所以常见，部分原因是在任何给定的IPv4地址空间块中，活动主机的数量相对密集。
The 128 bits of IPv6 [1] address space is considerably bigger than the 32 bits of address space in IPv4. In particular, the IPv6 subnets to which hosts attach will by default have 64 bits of host address space [2]. As a result, traditional methods of remote TCP or UDP network scanning to discover open or running services on a host will potentially become less feasible, due to the larger search space in the subnet. Similarly, worms that rely on off-link network scanning to propagate may also potentially be more limited in impact. This document discusses this property of IPv6 and describes related issues for IPv6 site network administrators to consider, which may be useful when planning site address allocation and management strategies.
IPv6[1]的128位地址空间比IPv4中的32位地址空间大得多。特别是，默认情况下，主机连接到的IPv6子网将具有64位的主机地址空间[2]。因此，传统的远程TCP或UDP网络扫描方法发现主机上打开的或正在运行的服务可能变得不太可行，因为子网中有更大的搜索空间。类似地，依赖非链接网络扫描传播的蠕虫也可能受到更大的影响。本文讨论了IPv6的这一特性，并描述了IPv6站点网络管理员考虑的相关问题，这在规划站点地址分配和管理策略时可能是有用的。
For example, many worms, like Slammer, rely on such address scanning methods to propagate, whether they pick subnets numerically (and thus probably topologically) close to the current victim, or subnets in random remote networks. The nature of these worms may change, if detection of target hosts between sites or subnets is harder to achieve by traditional methods. However, there are other worms that propagate via methods such as email, for which the methods discussed in this text are not relevant.
例如，许多蠕虫，如Slammer，依靠这种地址扫描方法进行传播，无论它们是从数字上（因此可能是拓扑上）选择靠近当前受害者的子网，还是随机远程网络中的子网。如果传统方法难以检测站点或子网之间的目标主机，则这些蠕虫的性质可能会发生变化。然而，还有其他蠕虫通过电子邮件等方法传播，本文中讨论的方法与此无关。
It must be remembered that the defence of a network must not rely solely on the unpredictable sparseness of the host addresses on that network. Such a feature or property is only one measure in a set of measures that may be applied. This document discusses various measures that can be used by a site to mitigate attacks as part of an overall strategy. Some of these have a lower cost to deploy than others. For example, if numbering hosts on a subnet, it may be as cheap to number hosts without any predictable pattern as it is to number them sequentially. In contrast, use of IPv6 privacy extensions [3] may complicate network management (identifying which hosts use which addresses).
必须记住，网络的防御不能仅仅依赖于该网络上主机地址的不可预测稀疏性。此类特征或属性只是可应用的一组度量中的一个度量。本文档讨论了作为总体策略的一部分，站点可以用来缓解攻击的各种措施。其中一些的部署成本比其他的低。例如，如果对子网上的主机进行编号，则对没有任何可预测模式的主机进行编号可能与按顺序对其进行编号一样便宜。相反，使用IPv6隐私扩展[3]可能会使网络管理复杂化（识别哪些主机使用哪些地址）。
This document complements the transition-centric discussion of the issues that can be found in Appendix A of "IPv6 Transition/ Co-existence Security Considerations" [12], which takes a broad view of security issues for transitioning networks. The reader is also referred to a recent paper by Bellovin on network worm propagation strategies in IPv6 networks [13]. This paper discusses some of the issues included in this document, from a slightly different perspective.
本文件补充了“IPv6过渡/共存安全注意事项”[12]附录A中以过渡为中心的问题讨论，该附录对过渡网络的安全问题进行了广泛的讨论。读者还可以参考Bellovin最近关于IPv6网络中网络蠕虫传播策略的论文[13]。本文从稍微不同的角度讨论了本文件中包含的一些问题。
There are significantly different considerations for the feasibility of plain, brute-force IPv4 and IPv6 address scanning.
对于普通、暴力IPv4和IPv6地址扫描的可行性，存在着明显不同的考虑因素。
A typical IPv4 subnet may have 8 bits reserved for host addressing. In such a case, a remote attacker need only probe at most 256 addresses to determine if a particular service is running publicly on a host in that subnet. Even at only one probe per second, such a scan would take under 5 minutes to complete.
典型的IPv4子网可能为主机寻址保留8位。在这种情况下，远程攻击者最多只需探测256个地址即可确定特定服务是否在该子网中的主机上公开运行。即使每秒只有一个探头，这样的扫描也需要不到5分钟的时间来完成。
A typical IPv6 subnet will have 64 bits reserved for host addressing. In such a case, a remote attacker in principle needs to probe 2^64 addresses to determine if a particular open service is running on a host in that subnet. At a very conservative one probe per second, such a scan may take some 5 billion years to complete. A more rapid probe will still be limited to (effectively) infinite time for the whole address space. However, there are ways for the attacker to reduce the address search space to scan against within the target subnet, as we discuss below.
典型的IPv6子网将为主机寻址保留64位。在这种情况下，远程攻击者原则上需要探测2^64个地址，以确定特定的开放服务是否在该子网中的主机上运行。以非常保守的每秒一个探头的速度，这种扫描可能需要大约50亿年才能完成。对于整个地址空间，更快速的探测仍将（有效地）限制在无限时间内。但是，正如我们在下面讨论的，攻击者可以通过一些方法来减少目标子网内要扫描的地址搜索空间。
The IPv6 host address space through which an attacker may search can be reduced in at least two ways.
攻击者可以通过至少两种方式减少其搜索的IPv6主机地址空间。
First, the attacker may rely on the administrator conveniently numbering their hosts from [prefix]::1 upward. This makes scanning trivial, and thus should be avoided unless the host's address is readily obtainable from other sources (for example, it is the site's published primary DNS or email Mail Exchange (MX) server). Alternatively, if hosts are numbered sequentially, or using any regular scheme, knowledge of one address may expose other available addresses to scan.
首先，攻击者可能依赖管理员方便地从[prefix]：：1开始对其主机进行编号。这使得扫描变得微不足道，因此应避免扫描，除非可以从其他来源（例如，它是站点发布的主DNS或电子邮件交换（MX）服务器）轻松获取主机地址。或者，如果主机按顺序编号，或者使用任何常规方案，则知道一个地址可能会暴露其他可用地址以进行扫描。
Second, in the case of statelessly autoconfiguring [1] hosts, the host part of the address will usually take a well-known format that includes the Ethernet vendor prefix and the "fffe" stuffing. For such hosts, the search space can be reduced to 48 bits. Further, if the Ethernet vendor is also known, the search space may be reduced to 24 bits, with a one probe per second scan then taking a less daunting 194 days. Even where the exact vendor is not known, using a set of common vendor prefixes can reduce the search. In addition, many nodes in a site network may be procured in batches, and thus have sequential or near sequential Media Access Control (MAC) addresses; if one node's autoconfigured address is known, scanning around that address may yield results for the attacker. Again, any form of sequential host addressing should be avoided if possible.
其次，在无状态自动配置[1]主机的情况下，地址的主机部分通常采用众所周知的格式，包括以太网供应商前缀和“fffe”填充。对于这样的主机，搜索空间可以减少到48位。此外，如果以太网供应商也是已知的，则搜索空间可以减少到24位，每秒扫描一个探头，然后花费更少的194天。即使不知道确切的供应商，使用一组通用的供应商前缀也可以减少搜索。此外，站点网络中的许多节点可以批量采购，因此具有顺序或接近顺序的媒体访问控制（MAC）地址；如果一个节点的自动配置地址已知，则扫描该地址可能会为攻击者带来结果。同样，如果可能，应避免任何形式的顺序主机寻址。
Full advantage of the increased IPv6 address space in terms of resilience to network scanning may not be gained until IPv6-only networks and devices become more commonplace, given that most IPv6 hosts are currently dual stack, with (more readily scannable) IPv4 connectivity. However, many applications or services (e.g., new peer-to-peer applications) on the (dual-stack) hosts may emerge that are only accessible over IPv6, and that thus can only be discovered by IPv6 address scanning.
考虑到大多数IPv6主机目前都是双栈的，并且具有（更容易扫描的）IPv4连接，因此，只有在纯IPv6网络和设备变得更加普遍之前，才能充分利用增加的IPv6地址空间对网络扫描的恢复能力。但是，（双堆栈）主机上的许多应用程序或服务（例如，新的对等应用程序）可能会出现，这些应用程序或服务只能通过IPv6访问，因此只能通过IPv6地址扫描来发现。
The problem faced by the attacker for an IPv6 network is also faced by a site administrator looking for vulnerabilities in their own network's systems. The administrator should have the advantage of being on-link for scanning purposes though.
IPv6网络的攻击者所面临的问题也是站点管理员在其网络系统中查找漏洞所面临的问题。不过，管理员应该有这样一个优势：出于扫描目的，可以访问链接。
If IPv6 hosts in subnets are allocated addresses 'randomly', and as a result IPv6 network scanning becomes relatively infeasible, attackers will need to find new methods to identify IPv6 addresses for subsequent scanning. In this section, we discuss some possible paths attackers may take. In these cases, the attacker will attempt to identify specific IPv6 addresses for subsequent targeted probes.
如果子网中的IPv6主机被“随机”分配地址，因此IPv6网络扫描变得相对不可行，则攻击者需要找到新方法来识别IPv6地址，以便进行后续扫描。在本节中，我们将讨论攻击者可能采取的一些路径。在这些情况下，攻击者将尝试识别后续目标探测的特定IPv6地址。
Note that in IPv6, an attacker would not be able to search across the entire IPv6 address space as they might in IPv4. An attacker may learn general prefixes to focus their efforts on by observing route view information (e.g., from public looking-glass services) or information on allocated address space from Regional Internet
请注意，在IPv6中，攻击者无法像在IPv4中那样搜索整个IPv6地址空间。攻击者可以通过观察路由视图信息（例如，来自公共窥镜服务）或区域互联网上分配的地址空间信息来了解通用前缀，从而集中精力
Registries (RIRs). In general, this would only yield information at most at the /48 prefix granularity, though some specific /64 prefixes may be observed from route views on some parts of some networks.
登记处（RIR）。通常，这最多只能产生/48前缀粒度的信息，尽管从某些网络的某些部分的路由视图中可以观察到某些特定的/64前缀。
Any servers that are DNS listed, e.g., MX mail relays, or web servers, will remain open to probing from the very fact that their IPv6 addresses will be published in the DNS.
DNS列出的任何服务器（例如MX邮件中继或web服务器）都将保持开放状态，以便进行探测，因为它们的IPv6地址将在DNS中发布。
While servers are relatively easy to find because they are DNS-published, any systems that are not DNS-published will be much harder to locate via traditional scanning than is the case for IPv4 networks. It is worth noting that where a site uses sequential host numbering, publishing just one address may lead to a threat upon the other hosts.
虽然服务器相对容易找到，因为它们是DNS发布的，但与IPv4网络相比，任何未发布DNS的系统都更难通过传统扫描找到。值得注意的是，如果站点使用顺序主机编号，仅发布一个地址可能会对其他主机造成威胁。
In the IPv6 world, a DNS zone transfer is much more likely to narrow the number of hosts an attacker needs to target. This implies that restricting zone transfers is (more) important for IPv6, even if it is already good practice to restrict them in the IPv4 world.
在IPv6世界中，DNS区域传输更有可能缩小攻击者需要攻击的主机数量。这意味着限制区域传输对IPv6来说（更）重要，即使在IPv4世界中限制区域传输已经是一种很好的做法。
There are some projects that provide Internet mapping data from access to such transfers. Administrators may of course agree to provide such transfers where they choose to do so.
有一些项目提供互联网地图数据，以获取此类传输。管理员当然可以同意在他们选择的地方提供此类传输。
IPv6 addresses may be harvested from recorded logs, such as web site logs. Anywhere else where IPv6 addresses are explicitly recorded may prove a useful channel for an attacker, e.g., by inspection of the (many) Received from: or other header lines in archived email or Usenet news messages.
IPv6地址可以从记录的日志（如网站日志）中获取。明确记录IPv6地址的任何其他地方都可能证明是攻击者的有用通道，例如，通过检查存档电子邮件或Usenet新闻消息中从：或其他标题行收到的（许多）信息。
More recent peer-to-peer applications often include some centralised server that coordinates the transfer of data between peers. The BitTorrent application builds swarms of nodes that exchange chunks of files, with a tracker passing information about peers with available chunks of data between the peers. Such applications may offer an attacker a source of peer IP addresses to probe.
最近的点对点应用程序通常包括一些集中式服务器，用于协调点对点之间的数据传输。BitTorrent应用程序构建了大量节点，这些节点交换文件块，跟踪器通过对等节点之间可用的数据块传递对等节点的信息。此类应用程序可能会向攻击者提供对等IP地址的来源以进行探测。
Where an Embedded Rendezvous Point (RP) [7] multicast group address is known, the unicast address of the RP is implied by the group address. Where unicast-prefix-based multicast group addresses [5] are used, specific /64 link prefixes may also be disclosed in traffic that goes off-site. An administrator may thus choose to put aside /64 bit prefixes for multicast group addresses that are not in use for normal unicast routing and addressing. Alternatively, a site may simply use their non-specific /48 site prefix allocation to generate RFC3306 multicast group addresses.
在已知嵌入式集合点（RP）[7]多播组地址的情况下，RP的单播地址由组地址暗示。在使用基于单播前缀的多播组地址[5]的情况下，特定/64链路前缀也可以在非现场的通信中公开。因此，管理员可能会选择为不用于正常单播路由和寻址的多播组地址保留/64位前缀。或者，站点可以简单地使用其非特定/48站点前缀分配来生成RFC3306多播组地址。
Specific knowledge of the target network may be gleaned if that attacker knows it is using 6to4 [4], ISATAP [10], Teredo [11], or other techniques that derive low-order bits from IPv4 addresses (though in this case, unless they are using IPv4 NAT, the IPv4 addresses may be probed anyway).
如果攻击者知道目标网络正在使用6to4[4]、ISATAP[10]、Teredo[11]或从IPv4地址派生低阶位的其他技术（尽管在这种情况下，除非他们使用IPv4 NAT，否则可能会探测IPv4地址），则可以收集目标网络的特定知识。
For example, the current Microsoft 6to4 implementation uses the address 2002:V4ADDR::V4ADDR while older Linux and FreeBSD implementations default to 2002:V4ADDR::1. This leads to specific knowledge of specific hosts in the network. Given one host in the network is observed as using a given transition technique, it is likely that there are more.
例如，当前的Microsoft 6to4实现使用地址2002:V4ADDR:：V4ADDR，而较旧的Linux和FreeBSD实现默认为2002:V4ADDR:：1。这将导致对网络中特定主机的特定了解。如果观察到网络中的一台主机使用给定的转换技术，则可能会有更多的主机。
In the case of Teredo, the 64-bit node identifier is generated from the IPv4 address observed at a Teredo server along with a UDP port number. The Teredo specification also allows for discovery of other Teredo clients on the same IPv4 subnet via a well-known IPv4 multicast address (see Section 2.17 of RFC 4380 [11]).
对于Teredo，64位节点标识符是根据Teredo服务器上观察到的IPv4地址以及UDP端口号生成的。Teredo规范还允许通过已知的IPv4多播地址在同一IPv4子网上发现其他Teredo客户端（参见RFC 4380[11]第2.17节）。
The main thrust of this text is considerations for off-link attackers or probing of a network. In general, once one host on a link is compromised, others on the link can be very readily discovered.
本文的主旨是考虑断开链接的攻击者或网络探测。一般来说，一旦链路上的一个主机被破坏，链路上的其他主机就很容易被发现。
If the attacker already has access to a system on the current subnet, then traffic on that subnet, be it Neighbour Discovery or application-based traffic, can invariably be observed, and active node addresses within the local subnet learnt.
如果攻击者已经可以访问当前子网上的系统，则该子网上的流量（无论是邻居发现流量还是基于应用程序的流量）都会被观察到，并且本地子网上的活动节点地址会被识别。
In addition to making observations of traffic on the link, IPv6- enabled hosts on local subnets may be discovered through probing the "all hosts" link-local multicast address. Likewise, any routers on the subnet may be found via the "all routers" link-local multicast address. An attacker may choose to probe in a slightly more obfuscated way by probing the solicited node multicast address of a potential target host.
除了观察链路上的流量外，还可以通过探测“所有主机”链路本地多播地址来发现本地子网上启用IPv6的主机。同样，子网上的任何路由器都可以通过“所有路由器”链路本地多播地址找到。攻击者可以通过探测潜在目标主机的请求节点多播地址，选择以稍微模糊的方式进行探测。
Where a host has already been compromised, its Neighbour Discovery cache is also likely to include information about active nodes on the current subnet, just as an ARP cache would do for IPv4.
当主机已经被破坏时，其邻居发现缓存也可能包含当前子网上活动节点的信息，就像ARP缓存对IPv4所做的那样。
Also, depending on the node, traffic to or from other nodes (in particular, server systems) is likely to show up if an attacker can gain a presence on a node in any one subnet in a site's network.
此外，根据节点的不同，如果攻击者能够在站点网络中的任何一个子网中的节点上获得存在，则与其他节点（特别是服务器系统）之间的通信量可能会出现。
A site may also have site- or organisational-scope multicast configured, in which case application traffic, or service discovery, may be exposed site wide. An attacker may also choose to use any other service discovery methods supported by the site.
站点还可以配置站点或组织范围的多播，在这种情况下，应用程序流量或服务发现可能会在站点范围内公开。攻击者还可以选择使用站点支持的任何其他服务发现方法。
There are some tools that site administrators can apply to make the task for IPv6 network scanning attackers harder. These methods arise from the considerations in the previous section.
站点管理员可以应用一些工具，使IPv6网络扫描攻击者的任务更加困难。这些方法源自上一节中的考虑因素。
The author notes that at his current (university) site, there is no evidence of general network scanning running across subnets. However, there is network scanning over IPv6 connections to systems whose IPv6 addresses are advertised (DNS servers, MX relays, web servers, etc.), which are presumably looking for other open ports on these hosts to probe further. At the time of writing, DHCPv6 [6] is not yet in use at the author's site, and clients use stateless autoconfiguration. Therefore, the author's site does not yet have sequentially numbered client hosts deployed as may typically be seen in today's IPv4 DHCP-served networks.
作者指出，在他目前（大学）的网站上，没有证据表明一般的网络扫描在子网之间运行。但是，通过IPv6连接可以对系统进行网络扫描，这些系统的IPv6地址已公布（DNS服务器、MX中继、web服务器等），这些系统可能正在这些主机上寻找其他开放端口以进行进一步探测。在撰写本文时，作者的站点尚未使用DHCPv6[6]，客户端使用无状态自动配置。因此，作者的站点尚未部署按顺序编号的客户端主机，这在今天的IPv4 DHCP服务网络中很常见。
Hosts in a network using IPv6 privacy extensions [3] will typically only connect to external systems using their current (temporary) privacy address. The precise behaviour of a host with a stable global address and one or more dynamic privacy address(es) when selecting a source address to use may be operating-system-specific, or configurable, but typical behaviour when initiating a connection is use of a privacy address when available.
使用IPv6隐私扩展[3]的网络中的主机通常仅使用其当前（临时）隐私地址连接到外部系统。选择要使用的源地址时，具有稳定全局地址和一个或多个动态隐私地址的主机的精确行为可能是操作系统特定的，也可能是可配置的，但启动连接时的典型行为是使用可用的隐私地址。
While an attacker may be able to port scan a privacy address, if they do so quickly upon observing or otherwise learning of the address, the threat or risk is reduced due to the time-constrained value of the address. One implementation of RFC 4941 already deployed has privacy addresses active (used by the node) for one day, with such addresses reachable for seven days.
虽然攻击者可能能够对隐私地址进行端口扫描，但如果他们在观察或以其他方式了解该地址后快速进行端口扫描，则由于该地址的时间限制值，威胁或风险会降低。已经部署的RFC 4941的一个实现具有一天的活动（由节点使用）隐私地址，七天内可以访问这些地址。
Note that an RFC 4941 host will usually also have a separate static global IPv6 address by which it can also be reached, and that may be DNS-advertised if an externally reachable service is running on it. DHCPv6 can be used to serve normal global addresses and IPv6 privacy addresses.
请注意，RFC 4941主机通常也会有一个单独的静态全局IPv6地址，也可以通过该地址访问该主机，如果在其上运行外部可访问的服务，则该地址可能是DNS广告。DHCPv6可用于提供普通全局地址和IPv6隐私地址。
The implication is that while privacy addresses can mitigate the long-term value of harvested addresses, an attacker creating an IPv6 application server to which clients connect will still be able to probe the clients by their privacy address when they visit that server. The duration for which privacy addresses are valid will impact the usefulness of such observed addresses to an external attacker. For example, a worm that may spread using such observed addresses may be less effective if it relies on harvested privacy addresses. The frequency with which such address get recycled could be increased, though this may increase the complexity of local network management for the administrator, since doing so will cause more addresses to be used over time in the site.
这意味着，虽然隐私地址可以降低捕获地址的长期价值，但创建客户端连接到的IPv6应用程序服务器的攻击者在客户端访问该服务器时仍然能够通过其隐私地址探测客户端。隐私地址有效的持续时间将影响这些观察到的地址对外部攻击者的有用性。例如，如果蠕虫依赖于收集的隐私地址，那么它可能会使用这些观察到的地址传播，效果可能会降低。回收此类地址的频率可能会增加，尽管这可能会增加管理员本地网络管理的复杂性，因为这样做会导致随着时间的推移在站点中使用更多的地址。
A further option here may be to consider using different addresses for specific applications, or even each new application instance, which may reduce exposure to other services running on the same host when such an address is observed externally.
这里的另一个选项可以是考虑针对特定应用程序使用不同的地址，或者甚至是每个新的应用实例，当外部观察到这样的地址时，可以减少对在同一主机上运行的其他服务的暴露。
The use of Cryptographically Generated Addresses (CGAs) [9] may also cause the search space to be increased from that presented by default use of stateless autoconfiguration. Such addresses would be seen where Secure Neighbour Discovery (SEND) [8] is in use.
使用加密生成地址（CGA）[9]也可能导致搜索空间比默认使用无状态自动配置时的搜索空间大。在使用安全邻居发现（SEND）[8]的地方可以看到这样的地址。
The EUI-64 identifier format does not require the use of MAC addresses for identifier construction. At least one well known operating system currently defaults to generation of the 64-bit interface identifier by use of random bits, and thus does not embed the MAC address. Where such a method exists, an administrator may wish to consider using that option.
EUI-64标识符格式不需要使用MAC地址来构造标识符。至少一个众所周知的操作系统目前默认使用随机位生成64位接口标识符，因此不嵌入MAC地址。在这种方法存在的情况下，管理员可能希望考虑使用该选项。
One option open to an administrator is to configure DHCPv6, if possible, so that the first addresses allocated from the pool begins much higher in the address space than at [prefix]::1. Further, it is desirable that allocated addresses are not sequential and do not have any predictable pattern to them. Unpredictable sparseness in the allocated addresses is a desirable property. DHCPv6 implementers could reduce the cost for administrators to deploy such 'random' addressing by supporting configuration options to allow such behaviour.
管理员可以选择的一个选项是配置DHCPv6（如果可能的话），以便从池中分配的第一个地址在地址空间中的起始位置远高于[prefix]：：1。此外，期望分配的地址不是顺序的，并且不具有任何可预测的模式。在分配的地址中不可预测的稀疏性是一个理想的属性。DHCPv6实现者可以通过支持允许这种行为的配置选项来降低管理员部署这种“随机”寻址的成本。
DHCPv6 also includes an option to use privacy extension [3] addresses, i.e., temporary addresses, as described in Section 12 of the DHCPv6 [6] specification.
DHCPv6还包括使用隐私扩展[3]地址（即临时地址）的选项，如DHCPv6[6]规范第12节所述。
Due to the much larger size of IPv6 subnets in comparison to IPv4, it will become less feasible for traditional network scanning methods to detect open services for subsequent attacks, assuming the attackers are off-site and services are not listed in the DNS. If administrators number their IPv6 subnets in 'random', non-predictable ways, attackers, whether they be in the form of automated network scanners or dynamic worm propagation, will need to make wider use of new methods to determine IPv6 host addresses to target (e.g., looking to obtain logs of activity from a site and scanning addresses around the ones observed). Such numbering schemes may be very low cost to deploy in comparison to conventional sequential numbering, and thus, a useful part of an overall defence-in-depth strategy. Of course, if those systems are dual-stack, and have open IPv4 services running, they will remain exposed to traditional probes over IPv4 transport.
由于与IPv4相比，IPv6子网的规模要大得多，因此传统的网络扫描方法在检测后续攻击的开放服务时变得不太可行，前提是攻击者不在现场，且服务未在DNS中列出。如果管理员以“随机”和不可预测的方式对其IPv6子网进行编号，则攻击者（无论是以自动网络扫描程序或动态蠕虫传播的形式）都需要更广泛地使用新方法来确定目标IPv6主机地址（例如，从站点获取活动日志，并扫描观察到的站点周围的地址）。与传统的顺序编号相比，此类编号方案的部署成本可能非常低，因此是整体纵深防御战略的一个有用部分。当然，如果这些系统是双堆栈的，并且运行开放式IPv4服务，则它们仍将暴露于IPv4传输上的传统探测。
There are no specific security considerations in this document outside of the topic of discussion itself. However, it must be noted that the 'security through obscurity' discussions and commentary within this text must be noted in their proper context. Relying
本文档中没有讨论主题之外的具体安全注意事项。但是，必须注意的是，必须在适当的上下文中注意本文本中的“通过模糊实现的安全”讨论和评注。依靠
purely on obscurity of a node address is not prudent, rather the advice here should be considered as part of a 'defence-in-depth' approach to security for a site or network. This also implies that these measures require coordination between network administrators and those who maintain DNS services, though this is common in most scenarios.
单纯考虑节点地址的模糊性是不明智的，这里的建议应该被视为站点或网络安全“纵深防御”方法的一部分。这也意味着这些措施需要网络管理员和维护DNS服务的人员之间的协调，尽管这在大多数情况下很常见。
Thanks are due to people in the 6NET project (www.6net.org) for discussion of this topic, including Pekka Savola, Christian Strauf, and Martin Dunmore, as well as other contributors from the IETF v6ops and other mailing lists, including Tony Finch, David Malone, Bernie Volz, Fred Baker, Andrew Sullivan, Tony Hain, Dave Thaler, and Alex Petrescu. Thanks are also due for editorial feedback from Brian Carpenter, Lars Eggert, and Jonne Soininen amongst others.
感谢6NET项目（www.6NET.org）中讨论此主题的人员，包括佩卡·萨沃拉、克里斯蒂安·斯特劳夫和马丁·邓莫尔，以及IETF v6ops和其他邮件列表中的其他贡献者，包括托尼·芬奇、大卫·马龙、伯尼·沃尔兹、弗雷德·贝克、安德鲁·沙利文、托尼·海恩、戴夫·泰勒和亚历克斯·佩特雷斯库。感谢Brian Carpenter、Lars Eggert和Jonne Soininen等人的编辑反馈。
[1] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998.
[1] Deering，S.和R.Hinden，“互联网协议，第6版（IPv6）规范”，RFC 2460，1998年12月。
[2] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007.
[2] Thomson，S.，Narten，T.和T.Jinmei，“IPv6无状态地址自动配置”，RFC 48622007年9月。
[3] Narten, T., Draves, R., and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, September 2007.
[3] Narten，T.，Draves，R.，和S.Krishnan，“IPv6中无状态地址自动配置的隐私扩展”，RFC 49412007年9月。
[4] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001.
[4] Carpenter，B.和K.Moore，“通过IPv4云连接IPv6域”，RFC 3056，2001年2月。
[5] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 Multicast Addresses", RFC 3306, August 2002.
[5] Haberman，B.和D.Thaler，“基于单播前缀的IPv6多播地址”，RFC3306，2002年8月。
[6] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.
[6] Droms，R.，Bound，J.，Volz，B.，Lemon，T.，Perkins，C.，和M.Carney，“IPv6的动态主机配置协议（DHCPv6）”，RFC3315，2003年7月。
[7] Savola, P. and B. Haberman, "Embedding the Rendezvous Point (RP) Address in an IPv6 Multicast Address", RFC 3956, November 2004.
[7] Savola，P.和B.Haberman，“将集合点（RP）地址嵌入IPv6多播地址”，RFC 3956，2004年11月。
[8] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005.
[8] Arkko，J.，Kempf，J.，Zill，B.，和P.Nikander，“安全邻居发现（SEND）”，RFC 39712005年3月。
[9] Aura, T., "Cryptographically Generated Addresses (CGA)", RFC 3972, March 2005.
[9] Aura，T.，“加密生成地址（CGA）”，RFC 39722005年3月。
[10] Templin, F., Gleeson, T., Talwar, M., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 4214, October 2005.
[10] Templin，F.，Gleeson，T.，Talwar，M.，和D.Thaler，“站点内自动隧道寻址协议（ISATAP）”，RFC 4214，2005年10月。
[11] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network Address Translations (NATs)", RFC 4380, February 2006.
[11] Huitema，C.，“Teredo：通过网络地址转换（NAT）通过UDP传输IPv6”，RFC 43802006年2月。
[12] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/ Co-existence Security Considerations", RFC 4942, September 2007.
[12] Davies，E.，Krishnan，S.，和P.Savola，“IPv6过渡/共存安全考虑”，RFC 49422007年9月。
[13] Bellovin, S., et al, "Worm Propagation Strategies in an IPv6 Internet", as published in ;login:, February 2006, <http://www.cs.columbia.edu/~smb/papers/v6worms.pdf>.
[13] Bellovin，S.等人，《IPv6互联网中的蠕虫传播策略》，发表于；登录：，2006年2月<http://www.cs.columbia.edu/~smb/papers/v6worms.pdf>。
Author's Address
作者地址
Tim Chown University of Southampton Southampton, Hampshire SO17 1BJ United Kingdom
提姆南安普敦大学，南安普顿，汉普郡SO17 1BJ英国
EMail: tjc@ecs.soton.ac.uk
EMail: tjc@ecs.soton.ac.uk
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