You cannot configure dhcpv6 stateless mode to be used by a. An attacker could exploit this vulnerability by sending a crafted request to an affected device that has the dhcp version 6 dhcpv6 server feature enabled, causing a reload. Dhcpv6 on cisco ios routers todays blogs is about dhcpv6 server setup on cisco ios routers. Now when it comes to dhcp for ipv6 rfc 3315, there are two ways dhcpv6 can be implemented, either stateful or stateless. Our dhcpv6 server will assign ipv6 addresses to all dhcpv6 clients and it will keep track of the bindings. Cisco 1841 ipv6 configuration ms does support dhcpv6, but windows any version, including 8. Therefore, the computer cannot obtain some additional network configuration parameters from a dhcpv6 server, such as the dns server address. Dhcpv6 dynamic host configuration protocol for ipv6 defined in rfc 3315 stateful counterpart to ipv6 stateless address autoconfiguration. Cisco ios software dhcp version 6 denial of service.
Ipv6 and junos stateful autoconfiguration with dhcpv6. Parameters can be provided statelessly, or in combination with stateful assignment of one or more ipv6 addresses andor ipv6 prefixes. Stateless autoconfiguration of ipv6 allows the client device to selfconfigure its ipv6. This protocol, that we simply call ndp, allows devices on a.
The local dhcpv6 server can then provide the imported configuration parameters to other dhcpv6 clients. How to configure dhcpv6 stateful autoconfiguration server and client dhcpv6 server command terms. A stateless dhcpv6 server can be used to provide information that might not be. Specify an interface type and number, and enters the interface configuration mode.
Stateless dhcpv6 is a combination of stateless address autoreconfiguration also known as slaac and dhcpv6. This command creates a pool and enters the router in dhcpv6 configuration mode. Scroll down and select the interface 2021 check box. Stateful dhcp is centrally managed on a dhcp servers. Some differences between ipv4 and ipv6 are more obvious than others. Dhcpv6 server stateless autoconfiguration feature information for dhcpv6 server stateless autoconfiguration ip addressing. This example is based on configuring a cisco 3750g24ts running 12. As part of my ongoing ipv6 testing, i was asked to look into stateful autoconfiguration for devices and host using dhcpv6. Ipv6 address assignment stateless, stateful, dhcp oh my.
This document discuss with an example how to configure stateless dhcpv6 in cisco ios routers. Dhcpv6 is not used to assign addresses, only to assign other configuration settings. Quick configs ipv6 dhcpv6 stateful, stateless, relay, managedconfigflag, otherconfigflag duration. Cisco ios software dhcp version 6 server denial of service. All configurations are tested in a lab environment involving asr series router as dhcp server and cisco 2800 series router as dhcp clients. This document describes the dynamic host configuration protocol for ipv6 dhcpv6. Stateless dynamic host configuration protocol service for ipv6 dhcpv6 is used by nodes to obtain configuration information, such as the addresses of dns recursive name servers, that does not require the maintenance of any dynamic state for individual clients. These contain the complete ipv6 functionality from kame at the latest development stage and have to be manually integrated in the. I had already looked into stateless address auto configuration and looked into another method of providing stateful autoconfiguration using a dual stacked dhcp server. Everybody seems to remember slaac and its stateless autoconfig aka autoconf setup, but most people always forget theirs a dhcpv6 component. This command is required to inform the clients that they should use dhcpv6 to obtain extra information such a dns server address, while using autoconfiguration to obtain ipv6 addressing.
In fact, we are talking about two different approaches. After verification that stateless dhcpv6 is functioning correctly, you will change the configuration on r1 to use stateful dhcpv6. Specify the ip addresses that the dhcpv6 server should assign to dhcpv6 clients. In this we will see how configure stateful dhcpv6 in cisco ios routers. A node that uses stateless dhcp must have obtained its ipv6 addresses through some other mechanism, typically. Rfc 8415 dynamic host configuration protocol for ipv6. Configuring dhcpv6 both stateless and stateful in packet. Stateless dhcpv6 server and client autoconfiguration. I understand that stateful dhcpv6 cannot provide hosts with a default router, as dhcpv4 could. In this one or more ipv6 addresses are assigned to the clients by using slaac and. Dhcp configuration guide, cisco ios xe gibraltar 16. This time ill be looking into how this could be done using juniper hardware, to be. Now 2021 appears in the interface field at the top.
Stateless dhcpv6 configuration on cisco router youtube. The lifetime option indicates the valid and preferred lease times in. Specify the dns ipv6 servers available to a dhcpv6 client. Configuring the stateless dhcpv6 client summary steps 1. The dhcpv6 will be used only for obtaining other configuration parameters such as dns, ntp. Carney sun microsystems july 2003 dynamic host configuration protocol for ipv6 dhcpv6 status of this memo this document specifies an internet standards track protocol. This is the first document in the document series implementing dhcpv6. In this configuration example,the router r1 is configured as dhcpv6 server and r2 is configured as relay agent. You need to be running an advanced ip services image. Stateless configuration also known as slaac stateless autoconfiguration the stateful version of dhcpv6 is pretty much the same as for ipv4. Stateless configuration also known as slaacstateless autoconfiguration the stateful version of dhcpv6 is pretty much the same as for ipv4. In this scenario, the computer does not change to dhcpv6 stateless mode, and instead remains in stateful mode. Dynamic host configuration protocol for ipv6 dhcpv6. Implementing dhcpv6 an introduction cisco community.
Cisco 910 industrial router software configuration guide. In short, the dhcpv6 servers knows exactly what ipv6 address has been assigned to what host. A vulnerability in the dhcp version 6 dhcpv6 server implementation of cisco ios software and cisco ios xe software could allow an unauthenticated, remote attacker to cause a denial of service dos condition. Not covered are ipv6 in accesslists and disabling stateless autoconfig. This will briefly describe how to get ipv6 routing working under ciscos ios. Stateless dhcpv6 is one of the most convenient method of implementing dhcpv6 in large networks. During the slaac process, the client receives information to create an ipv6 global unicast address. This command is used to indicate the pool of addresses to be allocated by the server. I did put the dhcpv6 pool to the right interface, so the three pcs in my vlan30 sales should. In stateful dhcp the adddress assignment is centrally managed and clients must obtain configuration information such as address autoconfiguration and neighbor discovery that is not available through. The switches used are cisco catalyst 2960s with cisco ios release 15.
Select system services dhcpv6 server dhcpv6 interface configuration. Dhcpv6 pd client often a cpe device to segment the received address ipv6 address space, and assign it dynamically to its ipv6 enabled interfaces. Todd lammle provides an overview of stateless and stateful autoconfiguration used wtih ipv6. Cisco ios software and cisco ios xe software contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service dos condition. The difference between stateless and stateful mode of a. No router is found or if router advertisement message enables use of dhcp using managedflag and otherconfigflag. I briefly discussed the difference already in my article about the ipv6 features. Lab configuring stateless and stateful dhcpv6 instructor. Another thing, in order to use stateless autoconfiguration in conjunction with a stateless dhcpv6 server, well add the command ipv6 nd otherconfigflag. I did put the dhcpv6 pool to the right interface, so the three pcs in my vlan30 sales should able to receive the ipv6 address, unless if i miss s. Stateful autoconfiguration of ipv6 is the equivalent to the use of dhcp in ipv4.
Rfc 3736 stateless dynamic host configuration protocol. First i created stateless dhcpv6 pool, but my stateful dhcpv6 pool seems to not working. Sean wilkins explains the new available methods for performing address configuration, how to implement dhcpv6 in ipv6, and the best options for stateless configuration. An attacker could exploit this vulnerability by sending malformed dhcpv6 packets to. The routers r3 and r4 are configured as dhcpv6client. This includes the default gateway information from the source ipv6 address in the ra message, which is the linklocal address of the router. Hosts would need to determine the default router based off of the information in ra packets. Sateless auto address configuration slaac slaac just means stateless auto address configuration, but it shouldnt be confused with stateless dhcpv6. Neighboring routers are configured to advertise nonlinklocal address prefixes from which ipv6 hosts derive stateless addresses. Stateful dhcpv6 autoconfiguration server and client. The router advertisement sets the dhcpv6 mode to stateless mode. Our dhcpv6 server will assign ipv6 addresses to all dhcpv6 clients and.
Hierarchical dynamic host configuration protocol for ipv6 dhcpv6 for stateless configuration parameters allows a stateless or stateful dhcpv6 client to export configuration parameters dhcpv6 options to a local dhcpv6 server pool. Slaac is the simplest way to give an ipv6 address to a client, because it exclusively rely on neighbor discovery protocol. The bulk of the dhcpv6 configuration, provisioning and tracking is done on the dhcpv6 server. While software from the kame project is used as ipv6 stacks in the bsd operating systems and as software packages for ipv6 subprotocols dhcpv6, mobile ip, kame also provides the socalled snapshots kamesnap. The vulnerability is due to improper parsing of malformed dhcpv6 packets. Dear all, i am setting up a dhcpv6 stateful server on my r1ny. In this method, the dhcpv6 server has the prefix delgation pd feature enabled and acts as delegating router. The routers used with ccna handson labs are cisco 1941 integrated services routers isrs with cisco ios release 15. The difference between stateless and stateful ipv6 autoconfiguration however, the most prominent confusion about setting up dhcpv6 on windows server 2008 r2 is the difference between stateless and stateful autoconfiguration. If you do not want this to happen, you need to specifically configure the router so it marks the router advertisement ra not to be used by the host to auto configure itself. In my lab, i have a cisco 7200 router r1 set up as a dhcpv6 server. It requires a dhcpv6 service to provide the ipv6 address to the client device and that both client device and server maintain the state of that address i. Stateless dhcpv6 stateless dhcpv6 is a combination of stateless address autoconfiguration and dynamic host configuration protocol for ipv6 and is specified by rfc3736.
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