How to solve the wrong IPv6 route Broadcast

IPv6 route broadcast is one of the new features of IPv6-the implementation of stateless automatic configuration. The IPv6 protocol specifies two automatic device configuration schemes, one is implemented by DHCPv6 and the other is stateless automatic configuration.

Vro broadcasts the prefix of the local subnet and the corresponding vro address. The new device automatically configures the network based on the information. The disadvantage of stateless automatic configuration is that DNS cannot be automatically configured. In response to the random release of DHCP information on an IPv4 network, releasing an incorrect prefix on an IPv6 network also interferes with users of local subnets, it is not easy to get the attention of network administrators, so it is necessary to know how to solve such an incorrect IPv6 route broadcast.

First, you must describe some basic knowledge. Similar to an IPv4 address, an IPv6 address consists of a network number and a host number. In most cases, the prefix and host number are 64-bit. It can be understood as the address space of a local subnet, so the probability of a crash caused by the construction of a host number is very small. Generally, the IPv6 stateless automatic configuration will provide the following address: 2001: da8: d800: 75: 204: 7dff: feb3: 16f4.

Here, the black part is the prefix broadcast by the IPv6 route, and the blue part is the first two digits of your MAC address may be different from the MAC address you see, because there is a addressing mode problem, but the following digits must be the same). The red ff: fe is a fixed value. A host may construct or be assigned multiple IPv6 addresses. When sending an IP packet, the host should select a specific address as the source address based on the longest prefix matching principle on the route table. If so, there is no need for the following troublesome solutions. The problem is that no one seems to be doing this.

Windows XP SP2/Windows XP SP3

The IPv6 stateless configuration of Windows XP cannot be disabled automatically, and the automatically configured permanent address cannot be deleted.

If the expected error message starts with 2002:, it is easier to solve this problem. You can use prefix policy to specify an address starting with 2001.

netsh int ipv6 set p 2001::/16 1 1 persistent

If the error broadcast starts with "2001:", the prefix policy does not work in this case, and the last configured address is directly used as the source address. Therefore, the solution is to turn off the function of automatically generating a temporary address every five minutes, and then manually configure a correct IPv6 address and gateway. Run netsh in the command line to enter netsh. The following operations are performed in netsh:

Int ipv6
Set pri dis
Show int # Check the Idx corresponding to your network card. Enter this number in the Idx field below and an IPv6 Address in the Address field. For example, I like to put ff: fill in the address after fe is changed to ff: ff.
Add addr Idx Address
Add r: 0/0 Idx gateway address
Quit # exit

Windows Vista/Windows 7/Windows Server 2008

In Versions later than Windows Vista, IPv6 stateless automatic configuration can finally be disabled.

Netsh interface ipv6 set interface "name of your local connection, for example, 'local connection 1'" routerdiscovery = disable

Linux

There are three methods in Linux. The first two methods are similar. One is to reject IPv6 route broadcast, and the other is to disable automatic configuration. Both are runtime kernel parameter, and the former is in net. ipv6.conf. . Accept_ra, set 0 to reject; the latter to net. ipv6.conf. . Autoconf, set 0 to disabled. Set one. Then you can manually set the address and gateway.

Another way is to use ip6tables to discard packets sent by the router with the error broadcast. The following command adds the rule to ip6tables. You need to know the MAC address of the router that sends the wrong broadcast. You can easily find the sender of the Advertisement by using tools such as tcpdump and wireshark ).

Ip6tables-a input-p icmpv6-m mac -- mac-source "vromac MAC address"-j DROP

Some distributions have/etc/network/if-pre-up.d/icmpv6-routerfilt files that can be configured directly in.